electronics
MOYB2
Novel undulators: the long and winding road to brightness
1
Storage rings and free electron lasers use undulators to produce high-brilliant X-ray photon beams. In order to increase brilliance and photon energy tunability it is necessary to enhance the undulator magnetic peak field on axis by reducing its period without decreasing the electron beam stay clear. Undulator technologies aiming to reach this goal are presented.
Paper: MOYB2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOYB2
About: Received: 14 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOZD2
A novel Vlasov approach for modeling electron cloud instabilities
8
This presentation discusses the generalization of the two-dimensional impedance model in the presence of an electron cloud. It will be discussed the implementation of a linear model of the e-cloud forces including both dipolar and quadrupolar forces to improve the modeling of the electron cloud instabilities. The linear model is included in the Vlasov equation, which allows for finding unstable modes. Benchmarking with conventional macro-particle tracking codes by also implementing the same linear model is discussed for negative, low, as well as large chromaticity. It is found that the instability modes by Vlasov agree well with those of the macro-particle simulations, using the same linear model for negative and low chromaticity. For large-chromaticity, the mode visible in the macro-particle simulations is among the unstable Vlasov modes. The present status of the checks with impedance-driven instabilities is being discussed also including recent benchmarking against tracking simulations and measurements.
Paper: MOZD2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOZD2
About: Received: 11 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOCD1
X-band high gradient accelerating structure for VIGAS project at Tsinghua university
14
A light source project named Very Compact Inverse Compton Gamma-ray Source (VIGAS) is under development at Tsinghua University. VIGAS aims to generate monochromatic high-energy gamma rays by colliding a 350 MeV electron beam with a 400-nm laser. To produce a high-energy electron beam in a compact accelerator with a length shorter than 12 meters, the system consists of an S-band high-brightness injector and six X-band high-gradient accelerating structures. The X-band structure’s frequency is 11.424 GHz, and it adopts a constant gradient traveling wave approach; thus, the iris from the first cell to the end cell is tapered. The total cell number is 72, so we named it XT72. In the last two years, we conducted the design, fabrication, and tuning of the first prototype of XT72. Recently, we finished the high-power test, and the result demonstrates that it has the ability to work at an 80 MV/m gradient. In this paper, we present the latest update on this structure.
Paper: MOCD1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOCD1
About: Received: 05 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPC04
Study of orbital effects on EIC detector synchrotron radiation background
40
Synchrotron radiation could contribute to detector background significantly, especially when the electron beam deviates from the design orbit. Without effective control, synchrotron radiation could impede physics data taking or even damage detector components. One of the key contributors to suppress synchrotron radiation in the Electron-Ion Collider IR is to control the electron orbit upstream the detectors. Therefore, it is imperative to define the tolerance of orbit errors in the IR which requires studying the orbital effects on synchrotron radiation. In this report, we will present the studies of orbital effects on synchrotron radiation background in EIC IR, including beam offsets introduced by upstream dipole, correctors, and quadrupole offsets.
Paper: MOPC04
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC04
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPC10
Dust-induced beam losses in the Large Hadron Collider
59
Since the start of the Large Hadron Collider (LHC), dust-induced beam loss events resulted in more than hundred premature beam aborts and more than ten dipole quenches during proton physics operation. The events are presumably caused by micrometer-sized dust grains, which are attracted by the proton beams and consequently give rise to beam losses due to inelastic proton-nucleus collisions. Besides the events which trigger dumps or quenches, a large number of smaller dust events has been detected by the beam loss monitors every year. Although these events are not detrimental for physics operation, they are still carefully scrutinized as they give a better understanding about the correlation with beam parameters, about the long-term evolution of event rates, and about possible correlations with shutdown activities and the installation of new equipment. In this contribution, we present a summary of observations from the first three runs of the LHC.
Paper: MOPC10
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC10
About: Received: 14 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPC22
Lattice optimization of RF electron linac designed for VEGA LCS gamma-ray source
107
The Variable Energy Gamma (VEGA) System is under implementation in Bucharest-Magurele Romania as one of the major components in the project of Extreme Light Infrastructure Nuclear Physics (ELI-NP). The VEGA System is designed as an advanced Laser Compton Scattering gamma-ray source with unique parameters in terms of high spectral density, monochromaticity, high polarizability, and energy tunability. It brings new opportunities and is dedicated for photonuclear research in both applied and fundamental physics, and will be open for worldwide users. Optimization of spectral density and guaranty of monochromaticity of the gamma-rays impose the necessity to control both, transverse emittance and energy spread, putting strong requirements on electron beam dynamics. The paper presents results from computer simulations carried out for the injector of the LCS gamma-ray source based on a normal-conducting RF LINAC, and investigation of a lattice configuration to optimize the electron beam parameters at the transfer line and storage ring entrance.
Paper: MOPC22
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC22
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPC23
Generating Super-Gaussian distribution and uniform sliced energy spread bunch for EIC strong hadron cooling
110
Strong Hadron Cooling (SHC), utilizing the coherent electron cooling scheme, has been extensively investigated for the Electron Ion Collider (EIC). Throughout our cooling optimization studies, we realized that a Super-Gaussian electron bunch offers enhanced performance in comparison to a Gaussian bunch. Our approach involves initiating the electron beam distribution in a double peak form, transitioning them into a Super-Gaussian distribution due to the longitudinal space charge. Subsequently, a chicane within the linac section compresses the bunch to meet the required bunch length. We tuned a third harmonic cavity amplitude to reduce the nonlinear term of the chicane. Moreover, given the low initial current leading to a small but non-uniform slice energy spread, we evaluated utilizing laser heating techniques to achieve a uniformly distributed slice energy spread. In this report, we discuss the concepts and simulation results.
Paper: MOPC23
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC23
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPC24
The design progress of a high charge low energy spread polarized pre injector for Electron Ion Collider
114
The polarized pre-injector for the Electron-Ion Collider is intended to produce four bunches every second, each containing 7 nC, with 85% polarization along the longitudinal axis, for injection into the Rapid Cycling Synchrotron. The pre-injector consists of a polarized electron source, bunching section, longitudinal phase space manipulation, and SLC-Type LINAC. To reduce energy spread and increase bunch length, a compact zig-zag chicane and dechirp cavity rotate the bunch in longitudinal phase space. In this paper, we will discuss the progress of recent pre-injection design and RF frequency selection. Additionally, we will examine the effects of wakefield, as well as coherent and incoherent synchrotron radiation on beam quality.
Paper: MOPC24
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC24
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPC25
Enhancing beam intensity in RHIC EBIS beamline via GPTune machine learning-driven optimization
118
The utilization of machine learning techniques in accelerator research has yielded remarkable advancements in optimization strategies. This paper presents a pioneering study employing a machine learning algorithm, GPTune, to optimize beam intensity by adjusting parameters within the EBIS injection and extraction beam lines. Demonstrating significant enhancements, our research showcases a remarkable 22% and 70% improvements in beam intensity at two different measurement locations.
Paper: MOPC25
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC25
About: Received: 08 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPC28
Status of the commissioning of the X-band injector prototype for AWAKE Run 2c
121
The status of commissioning of the electron injector intended for the next phase of the proton driven wakefield experiment (AWAKE) is presented, showing first experimental results from operating the brazing-free electron gun. To provide a high-quality electron beam, the UV laser was centered on the copper cathode, and a novel simplex and beam-based alignment of the focusing solenoid was performed. Measurements of the beam parameters and working points are addressed. The electron gun is shown to provide a high quality, stable and reproducible beam.
Paper: MOPC28
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC28
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPC41
Magnetic focusing architecture for a compact electron buncher
153
We present a beam-focusing architecture using electro- and permanent magnets for a novel compact electron beam buncher under development for space-borne electron accelerators. Developing compact and efficient accelerator components has become desirable with renewed interest in using space-borne electron beams for ionospheric aurora research and very low frequency wave generation for particle removal from the magnetosphere. An electron gun injects a direct current electron beam, and the buncher modulates the DC beam into periodic bunches at a frequency of 5.7 GHz. A 5.7 GHz linear accelerator in the downstream will capture the bunched beam with minimal acceptance mismatch. The beam modulation is done by three radiofrequency pillbox cavities. The buncher uses the electrostatic potential depression (EPD) method to shorten the structure length remarkably. The electron gun and a tunable solenoid provide the initial focusing of the beam. We then use a series of permanent magnets surrounding the buncher cavities clamped together by ferromagnetic steel plates to focus the beam through the buncher. Permanent magnets do not consume any power and weigh less than solenoid magnets, which provide equivalent focusing, making them ideal for use on a satellite or sounding rocket. We use the three-dimensional (3D) particle tracking solver from CST Studio Suite to simulate the beam-focusing.
Paper: MOPC41
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC41
About: Received: 15 May 2024 — Revised: 16 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPC43
Correction of the detector solenoid effect in the hadron storage ring of the Electron-Ion Collider
156
The Electron Ion Collider design strategy for reaching unprecedented luminosities and detection capabilities involves collision of flat bunches at a relatively large crossing angle. Effective head-on collisions are restored using crab cavities, which introduce a correlation of the particles' transverse coordinates with their longitudinal positions in the bunch, or crab dispersion. The collision geometry is further complicated by a tilt of the Electron Storage Ring plane with respect to that of the Hadron Storage Ring. In addition, the interaction point is placed inside the field of a detector solenoid. Reaching the design luminosity requires precise control of the 6D bunch distribution at the IP accounting for all of the aforementioned design features. This paper describes correction of the detector solenoid effect on the beam optics of the Hadron Storage Ring using a combination of local and global skew quadrupoles.
Paper: MOPC43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC43
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPC47
Design and status of SHINE injector
164
Shanghai HIgh repetitioN rate XFEL and Extreme light facility (SHINE) is an x-ray FEL facility, consisting of an 8 GeV CW superconducting linac and 3 FEL undulator lines, covering the spectral ranges 0.4-25 keV. Photoinjector using VHF gun is one of the key part of the facility. The installation of the electron gun section of the SHINE injector has been completed in August 2023. RF conditioning and commissioning were carried out from September to December. In this paper, we will introduce the installation progress of the injector and show some commissioning results of the electron gun section.
Paper: MOPC47
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC47
About: Received: 15 May 2024 — Revised: 29 May 2024 — Accepted: 29 May 2024 — Issue date: 01 Jul 2024
MOPC50
Optimization of beam emittance under the influence of geomagnetic field
170
The injector section of the SHINE device is currently in the debugging phase. The electron beam energy in the injector section is low and is significantly affected by the geomagnetic field, with an intensity of approximately 250 milligauss. Through theoretical optimization, adjustments to the positions and intensity parameters of helical coils and corrector magnets are being made to significantly reduce the growth of beam emittance under the influence of the geomagnetic field. The aim is to optimize the beam quality of the injector section of the SHINE device based on this model.
Paper: MOPC50
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC50
About: Received: 17 May 2024 — Revised: 23 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPC51
Capture cavities for the CW polarized positron source Ce⁺BAF
173
The initial design of the capture cavities for a continuous wave (CW) polarized positron beam for the Continuous Electron Beam Accelerator Facility (CEBAF) upgrade at Jefferson Lab is presented. A chain of standing wave multi-cell copper cavities inside a solenoid tunnel are selected to bunch/capture positrons in CW mode. The capture efficiency is studied with varying cavity gradients and phases. The heating load from the incoming particle radiation shower and RF field will limit the achievable gradients, especially the first cavity. The cooling method and results are shown. The beam loading cancellation from positrons and electrons are investigated.
Paper: MOPC51
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC51
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPC52
Toward a long-lifetime polarized photoelectron gun for the Ce+BAF positron source
176
The addition of spin-polarized, continuous-wave (c.w.) positron beams to the 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) would provide a significant capability to the experimental nuclear physics program at Jefferson Lab. Based on bremsstrahlung and pair-production in a high-Z target, the positron source requires a 120 MeV spin-polarized c.w. electron beam of several milliamperes. While the beam dynamics of the high-current electron beam are tenable, sustaining this current for weeks of user operations requires an unprecedented charge lifetime from a high-polarization GaAs-based photocathode. A promising approach to exceed the kilocoulomb charge lifetime barrier is reducing the ion back-bombardment fluence at the photocathode. By increasing the laser size and managing the emittance growth with an adequate cathode/anode design, significantly enhanced charge lifetime may be achieved. Based upon a new simulation model that qualitatively explains the lifetime data previously measured at different spot sizes, we describe the practical implications on the parameter space available for a kilocoulomb-lifetime polarized photogun design.
Paper: MOPC52
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC52
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPC57
Development of an S-band multi-beam accelerator for stationary CT application
195
Stationary CT is a novel CT technology to significantly improve scanning speed, by using distributed multiple ray sources instead of conventional helical rotation with single source. This work presents an S-band multi-beam accelerator as a multiple MV-level X-ray source for industrial stationary CT application. This accelerator consists of 7 parallel-distributed acceleration cavity and 6 coupling cavity, operating in pi/2 standing-wave mode with a centre frequency of 2998MHz. This structure can generate 0.7 MeV electrons with 100 mA peak current at each beamline according to the imaging requirement. The novel multiple high-energy X-ray source will fill in the blank of source requirements in industrial stationary CT application.
Paper: MOPC57
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC57
About: Received: 13 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPC61
Studies of space-charge compensation of positive ions by creating time-dependent secondary electrons in low-energy beam transport line
201
The space-charge neutralization of an ion beam by created electrons when the beam ionizes the gas is investigated using a three-dimensional electrostatic particle-in-cell code. Different kinds of injected gases are considered, and their space-charge compensation transient times are compared. The created secondary electrons by the beam collision with neutral gas along the beam trajectories are loaded in the simulation by a Monte Carlo generator, and their space charge contribution is added to the primary beam space charge densities. The injection and accumulation of secondaries are time-dependent and this process is continued until total space charge densities reach a steady state. In this study, a 2.4-meter LEBT line with two solenoid magnets is considered. Usually, the proton beam energy is 25 keV and the current level is around 10-15 mA. Additionally, beam extraction studies are conducted, and the extracted beam is used in both IBSIMU and Tracewin codes for LEBT lines to validate the results.
Paper: MOPC61
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC61
About: Received: 13 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPC62
Computational simulations and beamline optimizations for an electron beam degrader at CEBAF
204
An electron beam degrader is under development with the objective of measuring the transverse and longitudinal acceptance of the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. This project is in support of the CE+BAF positron capability. Computational simulations of beam-target interactions and particle tracking were performed integrating the GEANT4 and Elegant toolkits. A solenoid was added to the setup to control the beam's divergence. Parameter optimization of the solenoid field and magnetic quadrupoles gradient was also performed to further reduce particle loss through the rest of the injector beamline.
Paper: MOPC62
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC62
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPC64
Recycling magnets for the EIC electron storage ring
211
The Electron Storage Ring (ESR) of the Electron-Ion Collider requires some 400 quadrupoles and 200 sextupoles, plus dipole magnets and correctors. In an effort to reduce cost and relax the demand on the magnet vendor pool, used quadrupoles and sextupoles of the Advanced Photon Source at Argonne National Laboratory will be refurbished and installed in the ESR.
Paper: MOPC64
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC64
About: Received: 07 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPC67
The EIC accelerator: design highlights and project status
214
The design of the electron-ion collider (EIC) at Brookhaven National Laboratory is well underway, aiming at a peak electron-proton luminosity of 10e+34 cm^-1·sec^-1. This high luminosity, the wide center-of-mass energy range from 29 to 141 GeV (e-p) and the high level of polarization require innovative solutions to maximize the performance of the machine, which makes the EIC one of the most challenging accelerator projects to date. The complexity of the EIC will be discussed, and the project status and plans will be presented.
Paper: MOPC67
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC67
About: Received: 07 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPC68
Single line ERL permanent magnet FFA accelerator for LHeC
218
We present a Fixed-Field-Alternating (FFA) permanent magnet racetrack electron accelerator with energy range between 10-60 GeV for the future LHeC. Electron beam is brought back to the linac by the single beam line without requiring electric power REDUCING estimated wall power of 100 MW in the present LHeC design to a negligible power for arcs as the permanent magnets are used. The design is based on experience from the very successful commissioning of the Cornell University and Brookhaven National Laboratory Energy Recovery Test Accelerator – ‘CBETA’. The proposal supports sustainability efforts for LHeC by making a 'green' accelerator. It is an energy recovery linac with 99.9% energy efficiency and reduces the power consumption by using small permanent magnets. The FFA non-linear gradient design is a racetrack shape, where, as in the CBETA, the arcs are matched by adiabatic transition to the two (LHeC) or multiple straight sections. Two 10 GeV superconducting linacs are placed on both sides of the Interaction Region (IR) significantly reducing the power of synchrotron radiation loss.
Paper: MOPC68
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC68
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPC69
Permanent magnet electron energy synchrotron 2.5–18 GeV with fixed betatron tunes
222
We are presenting a design of a 2-18 GeV electron synchrotron accelerator made of permanent non-linear combined function magnets with fixed betatron tunes. It is based on the successfully commissioned CBETA Energy Recovery Linac where we used a single return beam line based on Fixed Field Alternating gradient (FFA) principle. The 2 GeV injection energy electrons come from the Recirculating Llnear Accelerator (RLA) with 500 MeV linac and a single FFA linear combined function magnet beam line to return electrons to the linac. The electron collision energy uses the same single beam line avoiding the RF accelerating cavities during selected number of turns.
Paper: MOPC69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC69
About: Received: 16 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPC71
Assessing global crabbing scheme feasibility for Electron-Ion Collider
226
The Electron-Ion Collider (EIC) plans to utilize the local crabbing crossing scheme. This paper explores the feasibility of adopting a single crab cavity with adjusted voltage, inspired by the successful global crabbing scheme in KEKB, to restore effective head-on collisions. Using weak-strong simulations, the study assesses the potential of this global crabbing scheme for the EIC while emphasizing the need for adiabatic cavity ramping to prevent luminosity loss. Additionally, the research outlines potential risks associated with beam dynamics in implementing this scheme.
Paper: MOPC71
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC71
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPC72
Advancing electron injection dynamics and mitigation approaches in the Electron-Ion Collider’s swap-out injection scheme
230
The Electron-Ion Collider (EIC) will use swap-out injection scheme for the Electron Storage Ring (ESR) to overcome limitations in polarization lifetime. However, the pursuit of highest luminosity with the required $28~\mathrm{nC}$ electron bunches encounters stability challenges in the Rapid Cycling Synchrotron (RCS). One method is to inject multiple RCS bunches into a same ESR bucket. In this paper we perform simulation studies investigating proton emittance growth and electron emittance blowup in this injection scheme. Mitigation strategies are explored. These findings promise enhanced EIC stability and performance, shaping potential future operational improvements.
Paper: MOPC72
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC72
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPC73
Design Updates to the EIC Electron Storage Ring Lattice
234
The Electron-Ion Collider (EIC) at Brookhaven National Laboratory will feature a 3.8-kilometer electron storage ring (ESR) that will circulate polarized beams with energies ranging from 5 to 18 GeV for collision with hadrons from a separate ring at luminosities up to 10^34 cm^{-2} s^{-1}. This contribution focuses on several recent changes to the lattice design of the ESR. Super-bend dipole triplets are used in the arc cells to increase the damping decrement and horizontal emittance at 5 GeV. Their lengths have recently been optimized to balance these two requirements. The interaction region has been modified to accommodate the requirements of a Compton polarimeter. Major changes have been made to IR8, which is the location of a possible second interaction region and detector that may be installed in a future upgrade. A design for a non-colliding IR8 has been developed that simplifies the setup to reduce initial costs and complexity. The latest lattice design of the ESR is presented here, and the major design choices are discussed.
Paper: MOPC73
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC73
About: Received: 13 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPC75
Progress on the design of the interaction region of the Electron-Ion Collider EIC
238
We present an update on the design of the Interaction Region (IR) for the the Electron Ion Collider (EIC) being built at Brookhaven National Laboratory (BNL). The EIC will collide high energy and highly polarized hadron and electron beams with a center of mass energy up to 140 GeV with luminosities of up to 10^34 /cm^2/s. The IR, located at RHIC's IR6, is designed to meet the requirements of the nuclear physics community as outlined in [1]. A second IR is technically feasible but not part of the project. The magnet apertures are sufficiently large to allow desired collision products to reach the far-forward detectors; the electron magnet apertures in the rear direction are chosen to be large enough to pass the synchrotron radiation fan. In the forward direction the electron apertures are large enough for non-Gaussian tails. The paper discusses a number of recent recent changes to the design. The machine free region was recently increased from 9 to 9.5 m to allow for more space in the forward direction for the detector. The superconducting magnets on the forward side now operate at 1.9 K, which helps crosstalk and space issues.
Paper: MOPC75
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC75
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPC76
Transversely driven coherent beam oscillations in the EIC electron storage ring
242
We study coherent transverse beam oscillations in the EIC electron storage ring (ESR), to specify the tolerance for high-frequency ripple of the magnet power supplies. To avoid unacceptable proton emittance growth from the oscillating beam-beam kick from the electrons, the amplitude of these oscillations at the proton betatron frequency needs to be limited to about 1e-4 fraction of the beam size at the interaction point. We show that the oscillations potentially caused by the ESR magnet dipole power supply ripple could be substantial, but still tolerable, if we account for the eddy current shielding in the vacuum chamber. Beam size oscillations, potentially caused by the rippling quadrupole magnet power supplies are also studied and appear manageable.
Paper: MOPC76
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC76
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPC77
Eddy current shielding of the magnetic field ripple in the EIC electron storage ring vacuum chambers
246
The EIC electron storage ring has very tight tolerances for the amplitude of electron beam position and size oscillations at the interaction point. The oscillations at the proton betatron frequency and its harmonics are the most dangerous because they could lead to unacceptable proton emittance growth from the oscillating beam-beam kick from the electrons. To estimate the amplitude of these oscillations coming from the magnet power supply current ripple we need to accurately account for the eddy current shielding by the copper vacuum chamber with 4-mm thick wall. At the frequencies of interest, the skin depth is a small fraction of the wall thickness, so the commonly used single-pole expressions for eddy current shielding transfer function do not apply. In this paper we present new (to the best of our knowledge) analytical formulas that adequately describe the shielding for this frequency range and chamber geometry and discuss the implications for the power supply ripple specifications at high frequency.
Paper: MOPC77
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC77
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPC78
Weak-strong beam-beam simulation with crab cavity noises for the hadron storage ring of the Electron-Ion Collider
250
The Electron Ion Collider (EIC), to be constructed at Brookhaven National Laboratory, will collide polarized high-energy electron beams with hadron beams, achieving luminosities of up to 1e+34 cm^−2 s^−1 in the center-mass energy range of 20-140 GeV. Crab cavities are employed to compensate for the geometric luminosity loss caused by a large crossing angle of 25 mrad in the interaction region. The phase noise in crab cavities will induce a significant emittance growth for the hadron beams in the Hadron Storage Ring (HSR). Various models have been utilized to study the effects of crab cavity phase noise. In this article, we present our numerical simulation results using a weak-strong beam-beam model. In addition to horizontal emittance growth, we also observed vertical emittance growth resulting from both crab cavity noises and beam-beam interaction. The tolerance for crab cavity phase noise was determined and compared with analytical predictions.
Paper: MOPC78
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC78
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPC79
Wide range tune scan for the hadron storage ring of the Electron-Ion Collider
254
The Electron Ion Collider (EIC), to be constructed at Brookhaven National Laboratory, will collide polarized high-energy electron beams with hadron beams, achieving luminosities up to 1e+34 cm^−2 s^−1 in the center-mass energy range of 20-140 GeV. The current fractional design tunes for the Hadron Storage Ring (HSR) are (0.228, 0.210) to mitigate the effects of synchro-betatron resonances. In this article, based on a strong-strong beam-beam simulation model, we carried out a wide range tune scan for the HSR to search for optimum working points. We found a good tune space around (0.735, 0.710), which is close to the working point (0.695, 0.685) of the polarized proton operation of the Relativistic Heavy Ion Collider (RHIC). We plan to further estimate the dynamic aperture and polarization with this working point.
Paper: MOPC79
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC79
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPC80
Global betatron coupling compensation for the hadron storage ring of the Electron-Ion Collider
258
The Electron Ion Collider (EIC), to be constructed at Brookhaven National Laboratory, will collide polarized high-energy electron beams with hadron beams, achieving luminosities up to 1e+34 cm^−2 s^−1 in the center-mass energy range of 20-140 GeV. The Hadron Storage Ring (HSR) of the EIC will utilize the arcs of the Relativistic Heavy Ion Collider (RHIC) and construct new straight sections connecting the arcs. In this article, we will examine all available skew quadrupoles currently in the HSR lattice and explore possible schemes for future global betatron coupling correction with RHIC-like decoupling feedback system. The effects of detector solenoids and quadrupole rolls are estimated at injection and stored energies. We also studied the decoupling requirements for generating and maintaining large transverse emittance ratio beams in the HSR.
Paper: MOPC80
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC80
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPC81
BAGELS: A general method for minimizing the rate of radiative depolarization in electron storage rings
262
We present a novel method for minimizing the effects of radiative depolarization in electron storage rings by use of vertical orbit bumps in the arcs. Electron polarization is directly characterized by the RMS of the so-called spin orbit coupling function in the bends. In the Electron Storage Ring (ESR) of the Electron-Ion Collider (EIC), as was the case in HERA, this function is excited by the spin rotators. Individual vertical orbit bumps in the arcs can have varying impacts on this function globally. In this method, we use a singular value decomposition of the response matrix of the spin-orbit coupling function with each orbit bump to define a minimal number of most effective groups of bumps, motivating the name “Best Adjustment Groups for ELectron Spin” (BAGELS) method. These groups can then be used to minimize the depolarizing effects in an ideal lattice, and to restore the minimization in rings with realistic closed orbit distortions. Furthermore, BAGELS can be used to construct groups for other applications where a minimal impact on polarization is desirable, e.g. global coupling compensation or vertical emittance creation. Application of the BAGELS method has significantly increased the polarization in simulations of the 18 GeV ESR, beyond achievable with conventional methods.
Paper: MOPC81
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC81
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPC83
Polarization preservation methods for the Electron Storage Ring of the EIC
270
The Electron Storage Ring (ESR) of the Electron-Ion Collider (EIC) to be built at Brookhaven National Laboratory will provide spin-polarized electron beams at 5, 10, and 18 GeV for collisions with polarized hadrons. Electron bunches with polarizations parallel and anti-parallel to the arc dipole fields will co-circulate in the ring at the same time, and each bunch must be replaced once it is sufficiently depolarized by synchrotron radiation. In this work, we detail the unique challenges posed by designing such a collider ring to operate at different energies, and their solutions. This includes satisfying spin matching conditions, calculating optimal energies for polarization, determining best figures-of-merit, maintaining high polarization without a traditional longitudinal spin match, restoring the spin match with random closed orbit distortions, and implementing global coupling compensation and vertical emittance creation schemes that preserve high polarization. Nonlinear tracking results are presented showing polarization requirements are exceeded.
Paper: MOPC83
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC83
About: Received: 13 May 2024 — Revised: 03 Jun 2024 — Accepted: 03 Jun 2024 — Issue date: 01 Jul 2024
MOPC85
Haissinski distribution of electron beam in Electron-Ion Collider and its impact on the hadron beam
274
The longitudinal distribution of the electron beam in the electron storage ring of the Electron-Ion Collider will be modified by the machine impedance. The modified distribution, combined with crab cavities may have an impact on the quality of the hadron beam during the collision. In this paper, we will explore the possible impact on the hadron beam quality with strong-strong and weak-strong beam-beam simulations.
Paper: MOPC85
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC85
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPC86
Status of the second interaction region design for Electron-Ion Collider
278
Provisions are being made in the Electron Ion Collider (EIC) design for future installation of a second Interaction Region (IR), in addition to the day-one primary IR. The envisioned location for the second IR is the existing experimental hall at RHIC IP8. It is designed to work with the same beam energy combinations as the first IR, covering a full range of the center-of-mass energy of ~20 GeV to ~140 GeV. The goal of the second IR is to complement the first IR, and to improve the detection of scattered particles with magnetic rigidities similar to those of the ion beam. To achieve this, the second IR hadron beamline features a secondary focus in the forward ion direction. The design of the second IR is still evolving. This paper reports the current status of its parameters, magnet layout, and beam dynamics and discusses the ongoing improvements being made to ensure its optimal performance
Paper: MOPC86
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC86
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPG02
An update on EIC rapid cycling synchrotron optics
285
The Electron-Ion Collider (EIC) requires continuous replacement of the stored electron bunches to facilitate arbitrary spin patterns in the Electron Storage Ring (ESR). This is accomplished by a dedicated, spin transparent Rapid Cycling Synchrotron (RCS). The dynamic range of the accelerator is from 400 MeV to 18 GeV. To maintain stability throughout the acceleration ramp, the linear and nonlinear optics must be tuned accordingly. In this paper, we will discuss the updated linear optics, chromaticities, and dynamic aperture of the RCS.
Paper: MOPG02
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG02
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPG06
Undulator radiation of single electrons: coherence length and quantum-optical properties
300
The aims of the CLARA experiment at the Fermilab Integrable Optics Test Accelerator (IOTA) were to directly measure the coherence length of undulator radiation emitted by a single electron and to test whether the radiation is in a pure classical Glauber coherent state or in a quantum mixture of coherent and Fock states. We used a Mach-Zehnder interferometer (MZI) to study visible radiation generated by 150-MeV electrons circulating in the ring. The relative delay between the two arms of the MZI was adjusted by varying the length of one of them with a resolution of 10 nm. The intensity of the circulating beam spanned several orders of magnitude, down to single electrons. A pair of single-photon avalanche diodes (SPADs) was placed at the output of the MZI arms to detect photocounts with high efficiency and timing resolution. We describe the observed interference patterns and photocount rates as a function of interferometer delay and discuss their implications.
Paper: MOPG06
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG06
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPG11
X-ray optics and diagnostics for the cavity-based X-ray free-electron laser project
319
The cavity-based x-ray free-electron laser (CBXFEL) R&D project utilizes a low-loss x-ray cavity (65.5 m long) to provide circulating monochromatized x-ray seeding for electrons from the Cu-linac at SLAC. The project aims to demonstrate the two-pass gain in x-ray regenerative amplifier and XFELO modes by 2024. Here, we report on the design, manufacture, and characterization of x-ray optical and diagnostic components for this project. The low-loss wavefront-preserving x-ray optical components include high-reflectivity C(400) diamond crystal mirrors, drumhead diamond crystal with thin membranes, beryllium refractive lenses, channel-cut Si monochromators, and exact-Backscattering C(440) diamond crystal. The x-ray diagnostics are designed to ensure the accuracy of beam alignment and to characterize and optimize CBXFEL performance. These include different types of x-ray beam position and profile monitors and x-ray beam intensity monitors, and a meV-resolution x-ray spectrograph. All x-ray optical and diagnostic components have been fully characterized with x-rays, and the mechanical installation of these components is expected to be finished soon.
Paper: MOPG11
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG11
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPG12
Thermoelastic response of Bragg crystals under MHz thermal loading
323
An x-ray free-electron laser oscillator (XFELO) is a promising candidate for producing fully coherent x-rays beyond the fourth-generation light sources. An R&D XFELO experiment (ANL-SLAC-Spring-8 collaboration) to demonstrate the basic principles and measure the two-pass FEL gain is expected to be accomplished by 2024. Beyond this R&D experiment, an XFELO user facility will be eventually needed to produce stable x-ray pulses with saturated pulse energy at MHz repetition rate. However, one of the outstanding issues for realizing an MHz XFELO is the possible Bragg crystal degradation due to the high-repetition-rate thermal loading of the high-pulse-energy x-rays. The deposited energy by one x-ray pulse induces temperature gradients and elastic waves in the crystal, where the deformed crystal lattice impacts the Bragg performance for subsequent x-ray pulses. Here, we report on the numerical study of the crystal thermoelastic response under thermal loading of x-ray pulse trains. The long-term decoupled thermoelastic behavior of the crystal and the possible mitigation of the thermal loading such as crystal cryogenical cooling will be discussed.
Paper: MOPG12
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG12
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPG13
Simulation of CXFEL with MITHRA code
327
The CXFEL project at ASU will produce coherent soft x-ray radiation at a university-scale facility. Unlike conventional XFELs, the CXFEL will use an optical undulator in addition to nanobunching the electron beam instead of a static magnetic undulator. This reduces the undulator period from cm-scale to micron scale and lowers the requirements on the electron beam energy. CXFEL’s overtaking geometry design reduces the effective undulator period to 7.86 μm to produce 1 keV photons. This is accomplished by crossing the laser and electron beam at a 30 degree overtaking angle, and using a tilted laser pulse front to maintain temporal overlap between the electron beam and laser pulse. The inverse Compton scattering interaction between a microbunched electron beam and an optical undulator falls out of the range of most accelerator codes. We employ MITHRA, a FEL full-wave FDTD solver software package which includes inverse Compton scattering to simulate the FEL lasing process. We have adapted the code to the CXFEL instrument design to simulate the radiation/electron beam interactions and report results of studies including scaling of key parameters.
Paper: MOPG13
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG13
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG14
The CXFEL project at Arizona State University
331
The CXFEL is designed to produce attosecond-femtosecond pulses of soft X-rays in the range 300-2500 eV using nanobunched electron beams and a very high power laser undulator. The project includes 5 X-ray endstations with applications in biology, quantum materials, and AMO science. The CXFEL Project overall includes both the CXFEL and the nonlasing hard X-ray CXLS that is described elsewhere in these proceedings. The CXFEL has recently completed a 3-year design phase and received NSF funding in March 2023 for construction over the next 5 years. Both CXFEL and CXLS instruments use recently developed X-band distributed-coupling, room-temperature, standing-wave linacs and photoinjectors operating at 1 kHz repetition rates and 9300 MHz RF frequency. They rely on recently developed Yb-based lasers operating at high peak and average power to produce fs pulses of 1030 nm light at 1 kHz repetition rate with pulse energy up to 400 mJ. We present the design and initial construction activities of the large collaborative effort to develop the fully coherent CXFEL.
Paper: MOPG14
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG14
About: Received: 23 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPG16
FLASH status – FEL user facility between two upgrade shutdowns
335
FLASH, the XUV and soft X-ray free-electron laser user facility at DESY, is in the transitional period between two substantial upgrade shutdowns within the FLASH2020+ upgrade project. FLASH consists of a common part FLASH0 (injector & superconducting linac), two FEL beamlines (FLASH1/2) and an experimental beamline FLASH3, accommodating the plasma wakefield experiment FLASHForward. The first (2021/22) shutdown was aimed at upgrading FLASH0 and install an APPLE-III undulator in the otherwise unchanged beamline FLASH2, enhancing the third harmonic at flexible output polarization. The next (2024/25) shutdown will focus on the complete exchange of the FLASH1 beamline to allow for externally seeded operation in the range from 60 nm down to 4 nm at 1 MHz bunch repetition rate (600 μs trains at 10 Hz train repetition rate). We report on the operation between the two shutdowns which was, to a large extend, dedicated to FEL operation for users and on the commissioning of the new features implemented in the last shutdown.
Paper: MOPG16
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG16
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG18
Integrating sustainable computational strategies in light source accelerator upgrades
343
The operation of light source accelerators is a complex process that involves a combination of empirical and theoretical physics, simulations, and data-intensive methodologies. For example, the FLASH1 beamline at DESY is upgrading to an external seeding FEL light source*. We utilize special diagnostics, machine learning algorithms, and comprehensive simulations to achieve this. To optimize resources, we constantly look to improve our approach, allowing us to robustly control the accelerator and meet the desired stability of our users. Machine learning and GPU-based algorithms have become crucial, enabling us to employ advanced optimization techniques and possibly AI. However, in many cases, it is imperative to establish a robust mechanism for simulations involving large particle numbers to ensure that future upgrades and experiments can effectively and sustainably leverage these computational strategies.
Paper: MOPG18
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG18
About: Received: 20 May 2024 — Revised: 27 May 2024 — Accepted: 27 May 2024 — Issue date: 01 Jul 2024
MOPG23
Characterization of FEL mirrors with long ROCs
350
FEL oscillators typically employ a two-mirror cavity with spherical mirrors. For storage ring FELs, a long, nearly concentric FEL cavity is utilized to achieve a reasonably small Rayleigh range, optimizing the FEL gain. A challenge for the Duke storage ring, with a 53.73 m long cavity, is the characterization of FEL mirrors with a long radius of curvature (ROC). The Duke FEL serves as the laser drive for the High Intensity Gamma-ray Source (HIGS). As we extend the energy coverage of the gamma-ray beam from 1 to 120 MeV, the FEL operation wavelength has expanded from infrared to VUV (1 micron to 170 nm). To optimize Compton gamma-ray production, the optimal value for the mirror's ROC needs to vary from 27.5 m to about 28.5 m. Measuring long mirror ROCs (> 10 m) with tight tolerances remains a challenge. We have developed two different techniques, one based on light diffraction and the other on geometric imaging, to measure the long ROCs. In this work, we present both techniques and compare their strengths and weaknesses when applied to measure mirror substrates with low reflectivity and FEL mirrors with high reflectivity.
Paper: MOPG23
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG23
About: Received: 16 May 2024 — Revised: 21 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPG25
FERMI plans for a 2 nm seeded FEL
357
Most FELs employ the mechanism of self-amplified spontaneous emission (SASE) from a relativistic electron beam to generate intense femtosecond pulses in the x-ray spectral region. Such SASE FELs are characterized by a broad bandwidth and relatively poor longitudinal coherence, and offer a rather limited control over the spectro-temporal properties. The limitations of a SASE FEL can be overcome by using an external laser to trigger the amplification process. Echo-enabled harmonic generation (EEHG), alone or in combination with the high-gain harmonic generation scheme (HGHG) is currently the most promising candidate to extend the operation of externally-seeded FELs into the soft x-ray region. Here, we discuss the plan at FERMI for the upgrade of the second FEL line in order to reach ~2 nm at the fundamental emission wavelength. In the first step, coherent radiation at ~10 nm will be generated with an EEHG layout and used as a seed in an HGHG stage on a fresh part of the electron beam. The experience with EEHG at the FEL-1 line will be an important step towards the final realization of the FERMI FEL as a reliable source of highly coherent radiation at ~2 nm and below.
Paper: MOPG25
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG25
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPG29
Numerical simulations of harmonic lasing at SASE2 beamline of European XFEL
360
In high-gain free-electron lasers (FELs) with planar undulators it is possible (in the linear regime) to independently amplify at the fundamental and at odd harmonics, a process referred to as Harmonic Lasing (HL). For the HL process preservation of the quality of the incoming high-brightness electron beam is essential. This requires suppression of the lasing at the fundamental, which can be achieved using several methods such as special phase shifter set points and attenuation of the fundamental radiation using intra-undulator optical high-pass filters. The European XFEL variable-gap undulator beamline SASE2 features two intra-undulator stations combining a magnetic chicane and the possibility to insert a thin diamond crystal onto the optical axis of the beamline. While installed for the operation in hard x-ray self seeding (HXRSS) mode, this hardware is well-suited for HL experiments at a low electron beam energy corresponding to a fundamental photon energy of about 2keV. In this contribution we present numerical simulations of third-harmonic lasing at this working point.
Paper: MOPG29
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG29
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG31
Conceptual design of the laser-plasma accelerator based soft X-ray Free Electron Laser
368
The conceptual design of the laser-plasma-based soft X-ray Free Electron Laser at ELI-Beamlines involves the integration of a novel high-power, high-repetition-rate laser, plasma source, compact LPA-based electron beam accelerator, dedicated electron beam line with relevant diagnostics, undulator beam line, photon beam line with required diagnostics, as well as a photon beam distribution system. The proposed concept of the whole setup is optimized to produce high-quality, coherent X-ray pulses with femtosecond duration in the ‘water-window’ wavelength of the photon radiation, which will be used by the photon user community for expiring research in the field of biology to study biological structures and processes at the cellular and molecular level at high resolution. In addition, the laser-plasma-based soft X-ray FEL will extend the abilities of users in material science to study nanostructures and thin films. In the frame of this report, we present the conceptual design for the full setup, which will be incorporated into the existing infrastructure of ELI-Beamlines. Furthermore, we discuss the key obstacles and the role of this project in the EuPRAXIA joint activity.
Paper: MOPG31
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG31
About: Received: 18 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPG32
Plasma accelerator based free electron laser program at ELI-ERIC (ELI-Beamlines)
372
The plasma accelerator-based Free Electron Laser research program at ELI-ERIC (ELI-Beamlines, Czech Republic) intends to utilize the unique qualities of plasma accelerators to build FELs with remarkable brightness, coherence, and pulse length. The program is based on the novel high-power, high-repetition-rate laser system, which is under preparation at ELI-Beamlines. The program entails expanding the LUIS experimental setup to test and validate the performance of the laser-plasma accelerator-based extreme ultra-violet (EUV) FEL, integrating a high-power laser, plasma source, and electron beam transport line with relevant diagnostics to create a comprehensive test bed for the development of the EuPRAXIA LPA-based FEL. The plasma accelerator-based FEL development program at ELI-Beamlines represents an innovative effort to expand the capabilities of FEL technology and open new possibilities for scientific research and industrial applications. In the frame of this report, we provide an overview of the relevant developments at ELI-ERIC (ELI-Beamlines) as well as the main challenges of this program.
Paper: MOPG32
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG32
About: Received: 18 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPG37
Simulation study for nanometer-scale modulation transfer in emittance exchange beamline
376
Generating nanometer-scale density modulation has been pursued due to its potential for compact X-ray source applications. Realization of this nanometer modulation involves two key challenges: development of sub-micron-scale momentum modulation method and conversion method to density modulation without quality degradation. Addressing the first challenge, emittance exchange (EEX) beamline is a promising candidate. Its unique capability of transverse-to-longitudinal phase space exchange makes it compatible with various modulators imparting either transverse or longitudinal modulations. This versatility allows us to find optimal radiators, addressing the second challenge. Study on degradation sources and their effects on the beam are underway to realize nanometer-scale modulation using EEX beamline. We present most recent results from our simulation study.
Paper: MOPG37
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG37
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPG47
Characterization of low-emittance electron beams generated by a new photocathode drive laser system NEPAL at the European XFEL
388
An ultrafast laser system for driving the photocathode RF gun at the European XFEL has been recently put into operation. The new laser system, NExt generation PhotocAthode Laser (NEPAL) is capable of providing drive laser pulses of variable pulse lengths and shapes, supporting the facility to extend its capabilities to operate in multiple user-desirable FEL modes. In this paper, we present a preliminary characterization of the low-emittance electron beams produced by NEPAL in the photoinjector. Both experimental and numerical results will be presented and discussed.
Paper: MOPG47
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG47
About: Received: 06 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG48
Overview of R&D activities in the production of high energy photon beams for future user experiments beyond 25 keV at the EuXFEL
392
Scientific opportunities with very hard XFEL radiation demands dedicated facility development towards FEL operation in the sub-ångström regime. Very hard X-rays provide capabilities of high Q-range coverage and high penetration, and also allow access to the K-edge spectroscopy of high-z materials. Production of such X-rays using FELs takes advantage of general FEL characteristics such as large coherence, short pulse option, variable pump-probe delay control and higher brightness compared to conventional storage ring sources. R$\&$D activities in the characterization and production of high energy photon beams beyond 25 keV has been launched since 2021 at the EuXFEL. Photon beams of 30 keV have been produced, characterized and delivered to experimental hutches. In this paper, we give an overview of the overall development. Obtained results will be discussed.
Paper: MOPG48
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG48
About: Received: 06 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPG53
Extreme pulse compression for impulsive ionization of valence wavepackets
396
We show how a chicane with anomalous dispersion can be used to compress an electron beam into a narrow, high-current, spike by exploiting the intrinsic chirp created by collective effects. We explore the limits of compression in a linearized model and then apply these beams to impulsively pump valence electrons. In the limit of an ultrashort electron beam, the valence electron wave-packet is accelerated so rapidly that the excited state forms an image of the bound state, allowing for unique insight into the structure of the electronic states of a molecule.
Paper: MOPG53
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG53
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPG55
The UK XFEL conceptual design and options analysis: mid-term update
400
The UK XFEL project is now mid-way through its three-year Conceptual Design and Options Analysis (CDOA) phase. The purpose of this phase is to develop concepts to meet the required ‘next-generation’ XFEL capabilities identified in the project’s peer-reviewed Science Case, developed by UK scientists. The envisaged next-generation features are a step-change in both the number of simultaneous experiments and in their capability – through multiple, combinable FEL sources delivering transform limited pulses across a wide range of photon energies and pulse durations, together with a comprehensive array of synchronised sources including high power lasers and particle beams. The project is assessing options to achieve this either via a new UK-based facility or by investment at existing XFELs, based on criteria that include performance, cost, and environmental sustainability. The project is holding a series of Town Hall meetings and workshops around the UK (see https://xfel.ac.uk) and is expanding collaborations nationally and internationally.
Paper: MOPG55
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG55
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPG65
Towards short-pulse generation at FLASH via laser-assisted electron bunch manipulation
404
The FLARE project aims to investigate special operation modes of the laser heater at the free-electron laser FLASH in Hamburg that enable the generation of few- or possibly sub-femtosecond soft X-ray pulses. To this end, laser pulses of the laser heater are split and then recombined after one pulse has been delayed. By controlling the interference of both pulses via their temporal overlap, a longitudinally non-uniform heating of the electron bunches can be achieved. Utilizing this, two short-pulse generation schemes are to be implemented as part of the FLARE project. In the first scheme, the energy spread of the bunch is increased to a degree that inhibits lasing, leaving only a small unheated region which emits a short FEL pulse. The second scheme works by imprinting an energy modulation with a linearly increasing amplitude onto the longitudinal phase-space distribution of the bunch. In subsequent magnetic chicanes, this phase-space structure results in a localized compression of the bunch, creating an extremely short current spike, which might be used to produce an X-ray pulse on the same time scale. The FLARE setup as well as first experimental results are presented.
Paper: MOPG65
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG65
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPG66
EUV FEL light source based on energy recovery linac with on-orbit laser plasma injection
408
We report on a week-long study of a conceptual design of EUV FEL light source based on an energy recovery linac with on-orbit laser plasma accelerator injection scheme. We carried out this study during USPAS Summer 2023 session of Unifying Physics of Accelerators, Lasers and Plasma applying the art of inventiveness TRIZ. An ultrashort Ti-sapphire laser accelerates electron beams from a gas target with mean energy of 20 MeV, which are then ramped up to 1 GeV in a five-turn scheme with a series of fixed field alternating magnets and two superconducting RF cavities (100 MeV per cavity per turn). The electron beam is then bypassed to an undulator line optimized to generate EUV light of 13.5 nm at kW level in a single pass.
Paper: MOPG66
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG66
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG67
Compact high average power THz source driven by thermionic RF gun
412
This work presents the design of a compact high-efficiency terahertz source, a collaborative effort between UCLA and RadiaBeam Technologies. The system, driven by a thermionic RF gun, features prebunching elements including alpha-magnet and electromagnetic chicane to effectively compress the long beam generated from the gun. By sending such beam into tapering enhanced waveguide oscillator, we can achieve high efficiency energy extraction in different regimes. This work focuses on the beam dynamics in the beamline prior injection into the undulator. A brief mention of the simulation results for radiation generation is also presented.
Paper: MOPG67
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG67
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPG68
Characterization of a single-pass high-gain THz FEL at PITZ
416
A single-pass THz free-electron laser (FEL) at the Photo Injector Test facility at DESY in Zeuthen (PITZ) was designed and implemented for a proof-of-principle experiment on a tunable high-power THz source for pump-probe experiments at the European XFEL. THz pulses are generated at a radiation wavelength of 100 μm within a 3.5 m long, strongly focusing planar LCLS-I undulator. High gain is achieved by driving the FEL with high brightness beams from the PITZ photoinjector at 17 MeV and a bunch charge of up to several nC. In addition to the mechanisms of self-amplified spontaneous emission (SASE), seeding of the THz-FEL by electron bunch modulation at the photocathode is also being investigated. The experimental results, including the gain curves and spectral properties of the THz-FEL radiation, are presented in comparison with theoretical predictions and numerical simulations.
Paper: MOPG68
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG68
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPG69
Simulations of dielectric-lined waveguide seeding option for THz FEL at PITZ
420
The first operational high peak and average power THz self-amplified spontaneous emission (SASE) free electron laser (FEL) at the Photo Injector Test facility at DESY in Zeuthen (PITZ) has demonstrated up to 100 uj single pulse energy at a center frequency of 3 THz from electron bunches of 2-3 nC. The measured shot-to-shot radiation pulse energy has a fluctuation of 10%. Shot-to-shot stability and temporal coherence in FELs can be greatly enhanced by the seeding method. In this paper, we propose the use of dielectric-lined waveguides (DLW) to enhance the initial seeding signal. Simulations of using electromagnetic wakefield in DLW to introduce energy modulation to the beam, controlling the conversion between energy modulation and density modulation, and space charge dominated beam matching in the chicane bunch compressor and the undulator will be presented.
Paper: MOPG69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG69
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPG70
Early lasing at LCLS and its implications for future cavity-based XFELs
424
Cavity-based XFEL, or CBXFEL, is a future photon source concept under intense development at SLAC. It is considered a path towards full 3D coherence at angstrom wavelength, delivering another 2-3 orders of magnitude leap in source brightness compared to current XFELs configurations. In a first phase of the project, one of the goals is to demonstrate the regenerative amplification by returning and amplifying the seed pulse from 7 LCLS Hard X-ray Undulators (HXUs) with a rectangular crystal cavity. In this paper, we report on the recent measurement of early stage XFEL lasing characteristics at 9.831 keV photon energy by using 7 LCLS HXUs under e-beam conditions close to those chosen for the first phase of CBXFEL gain demonstration.
Paper: MOPG70
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG70
About: Received: 17 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG71
Beam dynamics study for a high-repetition-rate infrared terahertz FEL facility
428
The paper introduces design and optimization of a high-repetition-rate infrared terahertz free-electron laser (IR-THz FEL) facility, which leverages optical resonator-based FEL technology to achieve a higher mean power output by increasing pulse frequency. Electron beam of the facility will be generated from a photocathode RF gun injector and further accelerated with a superconducting linear accelerator. Taking into account the collective effects, such as space charge, coherent synchrotron radiation (CSR), and longitudinal cavity wake field impacts, beam dynamics simulation for the injector, the accelerator, as well as the bunch compressor, has been done with codes of ASTRA and CSRTrack. With optimized microwave parameters of the linac, current profile with good symmetry has been obtained and the peak current can reach 100 A.
Paper: MOPG71
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG71
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPG72
Study on high energy coupling efficiency of laser-electron interaction via vortex beam
431
Manipulation electron beam phase space technology by laser-electron interaction has been widely used in accelerator-based light sources. The energy of the electron beam can be modulated effectively under resonant conditions by using an intense external laser beam incident into the undulator together with the electron beam. Enhancing the modulation efficiency is crucial for the performance of high repetition rate seeded free electron lasers (FELs) and other related devices. In this paper, we propose a new scheme to augment the efficiency of laser-electron interaction by employing the interaction between a vortex beam and an electron beam within a helical undulator. Three-dimensional time-dependent simulation results indicate that the modulation repetition rate of laser-electron interaction using a vortex beam can be improved by one order of magnitude over the conventional Gaussian beam at the same input power.
Paper: MOPG72
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG72
About: Received: 09 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPG73
Study of the radiation field from multiple out-coupling holes in an infrared free electron laser oscillator
435
A new infrared Free-Electron Laser (FEL) facility FELiChEM has been established as an experimental facility at the University of Science and Technology of China. It consists of two free electron laser oscillators which produce mid-infrared and far-infrared lasers covering the spectral range of 2-200 μm at the present stage. The output power is a crucial parameter for users, and it is usually achieved by an out-coupling hole located in the center of a cavity mirror. Nevertheless, the spectral gap phenomenon has been observed in FEL oscillators with partial waveguides as the output power is highly dependent on the mode configuration before the out-coupling mirror. Such power gaps have an adverse effect on experimental results since numerous experiments require continuous spectral scanning. In this paper, we propose the utilization of multiple out-coupling holes on the cavity mirror, instead of relying solely on a central out-coupling hole, to reduce the adverse impact of the spectral gap phenomenon.
Paper: MOPG73
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG73
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG74
Development progress of a tunable terahertz free electron laser based on a pre-bunched linear accelerator
438
To explore and detect novel effects and mechanisms inherent in materials, a tenable wavelength terahertz free electron laser (THz-FEL) is integrated into the terahertz near-field high-throughput material property testing system (NFTHZ). Employing a compact linear accelerator capable of adjusting electron energy within the range of 10 to 18 MeV as the injector, pre-bunching of electron bunches is implemented to create longitudinal spacing structures by manipulating the driving laser. By appropriately correlating the forming factor of electron bunches, electron beam energy at the undulator entrance, and the undulator K value, a terahertz free electron laser with peak power in the megawatt range and a central wavelength spanning from 0.5 to 5 THz can be achieved. This article provides an overview of the development progress of THz-FEL within the NFTHZ framework.
Paper: MOPG74
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG74
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPG76
A compact water window X-ray source based on inverse Compton scattering
441
X-rays in the water window (2.33 nm to 4.40 nm wavelength) can be used to provide high quality images of wet biological samples. Given the limited availability of current generation light sources in this energy range, table-top water window X-ray sources have been proposed as alternatives. We present start-to-end simulations in RF-Track of a water window X-ray source based on inverse Compton scattering. A brazing-free electron gun with a maximum beam energy of 7 MeV is considered, providing photon energies covering the full water window range. Performance estimates for the gun operating with copper and cesium telluride cathodes are presented. The cesium telluride cathode, combined with a burst mode Fabry-Perot cavity, allows for an increase in flux by orders of magnitude compared to single bunch copper cathode operation. A beamline of 1 m was determined to be sufficient to produce a high photon flux.
Paper: MOPG76
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG76
About: Received: 14 May 2024 — Revised: 28 May 2024 — Accepted: 28 May 2024 — Issue date: 01 Jul 2024
MOPG79
Calculation of focal spot of secondary X-rays generated by high-energy electron beam bombarding of heavy metal targets
445
One of the main methods to generate X-rays is to bombard metal targets with electron beams. However, this process introduces uncertainty in the electron transport, which leads to uncertainty in the position and momentum of the secondary X-rays. As a result, the focal spot of the X-rays is larger than the electron beam. In this paper, we use the Monte Carlo software Geant4 to investigate the conditions for minimizing the X-ray focal spot size. We assign different weights to the X-rays according to their energy components, based on the actual application parameters, and calculate the focal spot size for three target materials: lead, copper, and tungsten, finding that when the incident electron energy is in the MeV range and the electron source radius is 1 um, the mass thickness of the target of 1.935×10e-3 g/cm^2 is the limit for achieving the smallest equivalent focal spot size.
Paper: MOPG79
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG79
About: Received: 13 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR02
A compact electron accelerator for muon production
452
The muon is a unique particle. It is an elementary particle similar to the electron, but with a mass approximately 200 times greater. Because of their high penetrating power, muons can also be used for imaging such as non-destructive inspection and muon tomography for interior surveys of large structures. Muons derived exclusively from cosmic rays have heretofore been used for these applications, but the low rate and restricted angular range of cosmic rays restricts their usefulness.In this article, a compact and portable muon source based on super-conducting electron accelerator technology is considered. The addition of a muon accelerator provides a variable energy, portable muon source.
Paper: MOPR02
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR02
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPR15
Fabrication and testing of mode couplers for a 180 GHz colinear wakefield accelerator
485
A corrugated waveguide based collinear wakefield accelerator is under development at Argonne National Laboratory. The accelerating mode is operating at 180 GHz with a high average power level up to 600 W compounding at the end of the 0.5 m long accelerator module. It is extracted by a dedicated coupler to prevent excessive heating of the corrugated structure of the next accelerator module downstream. Also, it is necessary to monitor beam offsets from the center of the corrugated structure. It is done by utilizing the offset beam’s induced wakefield dipole mode at 190 GHz and extracting it to diagnostic electronics via the second dedicated coupler. Both are contained in the transition section between the accelerator modules*. This paper presents the mechanical design, fabrication, and performance testing of the transition section. Testing included mmWave measurements at ANL and electron beam measurements at Brookhaven National Lab’s Accelerator Test Facility. Both tests involved characterizations of the wakefield modes and coupler’s performances.
Paper: MOPR15
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR15
About: Received: 08 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPR17
Advanced accelerator concepts for dark sector searches and fast muon acceleration
489
Dielectric laser acceleration (DLA) is a promising approach to accelerate single electrons at a high repetition rate to GeV energies, for indirect dark matter searches. Relevant concepts include the integration of the dielectric structure inside the laser oscillator. To efficiently use muons for high energy physics applications, they need to be accelerated rapidly, before they decay. Plasma acceleration achieves GV/m accelerating fields and could be ideal for accelerating to muon-collider energies. Single muons could also be accelerated in DLAs for dark matter searches. They could be injected from existing low-intensity muon sources, such as the one at PSI. A workshop organized in the frame of the EU project “Innovation Fostering in Accelerator Science and Technology” (I.FAST) focused on GHz Rate & Rapid Muon Acceleration for Particle Physics to address these topics. We report highlights and future research directions.
Paper: MOPR17
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR17
About: Received: 13 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR18
Development of a de-focusing space charge lens for positive ion beams
493
Space charge lenses are ion-optical devices that focus an ion beam by the intrinsic electric field of confined non-neutral plasmas, for example electron clouds. This was first proposed by Dennis Gabor in the year 1947 and is therefore also known as Gabor-lenses. Previous studies have shown the strong linear focusing forces of a confined electron plasma. In this paper, the first confinement of a pure proton plasma in a Gabor-lens will be discussed. The confinement of a positive space charge column provides either a linear de-focusing force for positively charged ion beams or a linear focusing force for negatively charged heavy ion beams. Very first results of proton confinements and their diagnostics will be presented. A special focus lies on the diagnosis of the proton density distribution, as well as the comparison between the behavior of the proton and electron clouds.
Paper: MOPR18
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR18
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR19
Particle beam-driven wakefield in carbon nanotubes: hydrodynamic model vs PIC simulations
496
The interactions of charged particles with carbon nanotubes (CNTs) may excite electromagnetic modes in the electron gas that makes up the nanotube surface. This novel effect has recently been proposed as an alternative method to achieve ultra-high gradients for particle acceleration. In this contribution, the excitations produced by a localized point-like charge propagating in a single wall nanotube are described by means of the linearized hydrodynamic model. In this model, the electron gas is treated as a plasma with specific solid-state properties. The governing set of differential equations consists of the continuity and momentum equations for the electron fluid, in conjunction with Poisson's equation. Through numerical simulations, we investigate the influence of key factors, including the driving velocity, CNT radius, surface density and the friction (between the electron fluid and the ionic lattice) parameter, on the excited wakefields, comparing the results with Particle-in-Cell (PIC) simulations. A comprehensive discussion is presented to analyze similarities, differences and limitations of both methods. This research provides a valuable perspective on the potential use of CNTs to enhance particle acceleration techniques, paving the way for further advancements in high-energy physics and related fields.
Paper: MOPR19
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR19
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPR22
Microbunching instability test for emittance exchange-based photoinjector
500
Previous start-to-end simulations of an emittance exchange (EEX)-based photoinjector have demonstrated highly attractive beam properties. The EEX-based photoinjector can provide another interesting opportunity that potentially eliminate the microbunching instability issue. The space-charge and/or CSR-induced amplification occurs during density-to-energy and energy-to-density modulation conversion process. This amplification becomes particularly pronounced when multiple compressors are implemented. In contrast, the proposed EEX-based photoinjector doesn’t require additional compression process. Moreover, the initial longitudinal phase space becomes the transverse phase space, resulting in a significant reduction of space-charge and CSR’s longitudinal interaction. We present preliminary simulation results of microbunching instability in EEX-based photoinjector.
Paper: MOPR22
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR22
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPR25
Design, fabrication, and testing of a W-band corrugated waveguide for Wakefield acceleration
511
In the field of structure wakefield acceleration there is considerable interest in radiofrequency (RF) structures capable of producing high gradients. Structures in the sub-terahertz (sub-THz) regime are of note due to their high gradient and high efficiency, allowing for a low physical footprint. In the pursuit of this goal we have designed a metallic corrugated W-band structure using the CST Studio Suite. After optimizing for the maximum achievable gradient from a nominal Argonne Wakefield Accelerator (AWA) electron bunch at 65 MeV with a Gaussian distribution we attempted to achieve a higher transformer ratio using a shaped bunch. Shaped bunches such as these are achievable at the AWA emittance exchange (EEX) beamline. Preliminary results from the structure testing at AWA using shaped electron bunches will be presented. Further tests are planned, involving a comprehensive optimization of the beamline at AWA.
Paper: MOPR25
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR25
About: Received: 24 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPR31
Reduction of dark current at cryogenic temperatures in a high gradient photogun
523
The newly commissioned CYBORG (CrYogenic Brightness Optimized Radiofrequency Gun) beamline at UCLA operates in a high gradient, low temperature regime inaccessible to most other existing photoguns and cathode testing infrastructure. The beamline is designed to study electron emission in regime. The final intended configuration of the beamline will be used for studies of novel photocathodes including low mean transverse energy (MTE), high quantum efficiency (QE) semiconductor cathodes dependent on future laser improvement. In the near term, the unique environment allows us to study temperature dependent effects on dark current. Notable reduction in dark current at cryogenic temperatures was observed, a behavior not predicted by Fowler-Nordheim type field emission. Initial results are presented.
Paper: MOPR31
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR31
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR32
High gradient operation of cryogenic C-band RF photogun at UCLA
527
Future electron accelerator applications such as x-ray free electron lasers and ultrafast electron diffraction are dependent on significantly increasing beam brightness. We have designed and produced a new CrYogenic Brightness-Optimized Radiofrequency Gun (CYBORG) for use in a new beamline at UCLA to study the brightness improvements achievable in this novel low temperature high gradient accelerating environment. We are currently in the process of commissioning the photogun for operation with peak cathode fields in excess of 120 MV/m. We report here on the status of conditioning the photogun and report on dark current measurements and maximum field achieved thus far.
Paper: MOPR32
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR32
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPR38
An LWFA injector for AWAKE Run 2 experiment
535
A beam physics design has been carried out for a 200 MeV-LWFA injector to the AWAKE Run 2 experiment as an alternative to the reference RF injector. It is composed of a laser-plasma acceleration stage and a transport line. In addition to specific environment constraints that impose a dogleg configuration, the electron beam must feature unprecedented performances for a plasma-based accelerator: 100 pC charge, a few mm·mrad emittance, and a few % energy spread. Thanks to an integrated beam physics study assigning specific roles to each section of the accelerator, all the requirements are successfully met in numerical simulations, paving the way for plasma-based accelerators to be competitive with conventional accelerators.
Paper: MOPR38
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR38
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPR40
Progress towards high-quality, high-repetition-rate plasma acceleration at FLASHForward
541
Plasma-wakefield acceleration represents an exciting route towards reducing the footprint of future high-energy electron accelerators by accelerating bunches in fields exceeding 1 GV/m. One such technique employs a double-bunch structure where the trailing bunch is accelerated in the field of a high-amplitude plasma-density wake driven by the leading bunch. A future particle collider or photon science facility incorporating plasma accelerators will be required to accelerate up to millions of bunches per second with high energy efficiency while preserving the brightness of the accelerating bunch. This contribution presents the latest progress towards these goals at FLASHForward (DESY).
Paper: MOPR40
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR40
About: Received: 14 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR41
Results and plans for run 2 of the advanced proton driven plasma wakefield acceleration experiment AWAKE
545
This talk summarizes the plans, challenges and key components of the four phases in the AWAKE roadmap. In addition, an overview of the rich measurement program of the second phase, AWAKE Run 2b, during 2023 and 2024 is given. Results from a unique 3-week measurement opportunity with a 10m discharge plasma source prototype are shown, including the effects of different gases, plasma densities, bunch charges and plasma lengths on the proton bunch self-modulation, ion-motion, current filamentation instabilities and plasma light. A new 10 m long rubidium vapor source was installed in the summer of 2023 with the possibility to generate a density step (0-10%) every 50 cm along the first 4 m. First measurement results with this plasma cell are also presented, showing the positive effect of the density step on the plasma light as well as an increased energy gain for externally injected electrons.
Paper: MOPR41
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR41
About: Received: 10 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPR42
Preparation for Realisation of External Electron Injection for AWAKE Run 2b
549
The Advanced Wakefield Experiment (AWAKE) aims to accelerate electrons to particle physics relevant energies using self-modulated proton bunches as drivers in a single plasma. AWAKE is now in its Run 2b (2023-2024), where the goal is to stabilise wakefields by using a plasma density step. Experimental demonstrations require probing of the longitudinal wakefields by externally injected electron bunches. To optimise charge capture in the wakefields, the electron beam density should be maximised at the site of injection ze. This is achieved by setting the beam waist at ze. Since no diagnostics are currently available at these locations, waist beam sizes are extrapolated from measurements upstream. The qualitative and quantitative agreement obtained between measured and simulated transverse electron beam sizes, at locations where these can be measured, demonstrates good understanding of the beam line optics and provides confidence in the extrapolated beam sizes at waist locations, where these cannot be measured. This information can then be used in the experiment to maximise the beam density at the site of injection.
Paper: MOPR42
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR42
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPR44
Laser-plasma injector for an electron storage ring
557
Laser-plasma accelerators (LPAs) are compact accelerators with field gradients that are approximately 3 orders of magnitude higher than RF-based machines, which allows for very compact accelerators. LPAs have matured from proof-of principle experiments to accelerators that can reproducibly generate ultrashort high-brightness electron bunches. Here we will discuss a first combination of LPAs with an electron storage ring, namely an LPA-based injector for the cSTART ring at the Karlsruher Institute of Technology (KIT). The cSTART ring is currently in the final design phase. It will accept electron bunches with an energy of 50 MeV and will have a large energy acceptance to accommodate the comparably large energy spread of LPA-generated electron beams. The LPA will be required to reproducibly and reliably generate 50 MeV electron bunches with few percent energy spread. To that end, different controlled electron injection methods into the plasma accelerating structure, tailored plasma densities are explored and beam transfer lines to tailor the beam properties are designed.
Paper: MOPR44
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR44
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPR53
Instability of asymmetric electron drive beams in hollow plasma channels
561
Using hollow plasma channels is one approach to compact positron acceleration, potentially reducing the cost and footprint of future linear colliders. However, it is prone to transverse instabilities since beams misaligned from the channel axis tend to get deflected into the channel boundary. In contrast, asymmetric electron drive beams can tolerate misalignment and propagate stably after the initial evolution, but this has only been reported for short distances. In this work, we use quasi-static particle-in-cell simulations to demonstrate the instability of asymmetric drivers even after splitting into two beamlets and reaching equilibrium. As the driver decelerates, its particles gradually return into the channel, making the driver susceptible to deflection by the transverse dipole mode. To understand this behavior, the transverse motion of an individual beam particle is modeled. Strategies to mitigate this instability are also proposed.
Paper: MOPR53
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR53
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPR56
Design and modeling of HOFI plasma channels for laser plasma accelerators
565
Structured plasma channels are an essential technology for driving high-gradient, plasma-based acceleration and control of electron and positron beams for advanced concepts accelerators. Laser and gas technologies can permit the generation of long plasma columns known as hydrodynamic, optically-field-ionized (HOFI) channels, which feature low on-axis densities and steep walls. By carefully selecting the background gas and laser properties, one can generate narrow, tunable plasma channels for guiding high intensity laser pulses. We present on the development of 1D and 2D simulations of HOFI channels using the FLASH code, a publicly available radiation hydrodynamics code with specific improvements to model plasma channels. We explore sensitivities of the channel evolution to laser profile, intensity, and background gas conditions. We examine efforts to benchmark these simulations against experimental measurements of plasma channels. Lastly, we discuss ongoing work to couple these tools to community PIC models to capture variations in initial conditions and subsequent coupling for laser wakefield accelerator applications.
Paper: MOPR56
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR56
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPR57
Automated emittance and energy gain optimization for plasma wakefield acceleration
569
At the Facility for Advanced Accelerator Experimental Tests (FACET-II) accelerator, a pair of 10 GeV high-current electron beams is used to investigate Plasma Wakefield Acceleration (PWFA) in plasmas of different lengths. While PWFA has achieved astonishingly high accelerating gradients of tens of GeV/m, matching the electron beam into the plasma wake is necessary to achieve a beam quality required for precise tuning of future high energy linear accelerators. The purpose of this study was to explore how start-to-end simulations could be used to optimize two important measures of beam quality, namely maximizing energy gain and minimizing transverse emittance growth in a 2 cm long plasma. These two beam parameters were investigated with an in-depth model of the FACET-II accelerator using numerical optimization. The results presented in the paper demonstrate the importance of utilizing beam-transport simulations in tandem with particle-in-cell simulations and provide insight into optimizing these two important beam parameters without the need to devote significant accelerator physics time tuning the FACET-II accelerator.
Paper: MOPR57
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR57
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPR58
UV-Soft X-ray betatron radiation characterization from laser-plasma wakefield acceleration
573
The spontaneous emission of radiation from relativistic electrons within a plasma channel is called betatron radiation and has great potential to become a compact x-ray source in the future. We present an analysis of the performance of a broad secondary radiation source based on a high-gradient laser-plasma wakefield electron accelerator. The purpose of this study is to assess the possibility of having a new source for a non-destructive X-ray phase contrast imaging and tomography of heterogeneous materials. We report studies of compact and UV-soft X ray generation via betatron oscillations in plasma channel and in particular measurement of the radiation spectrum emitted from electron beam is analyzed from a grazing incident monochromator at Centro de Laseres Pulsados Ultraintensos (CLPU).
Paper: MOPR58
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR58
About: Received: 22 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR65
Comparison of flat beam PWFA analytic model with PIC simulations
583
This paper explores the phenomenon of asymmetric blowout in plasma wakefield acceleration (PWFA), where the transversely asymmetric beam creates a transversely asymmetric blowout cavity in plasma. This deviation from the traditional axisymmetric models leads to unique focusing effects in the transverse plane and accelerating gradient depending on the transverse coordinates. We extend our series of studies on plasma wakefield acceleration (PWFA) by comparing our recently developed analytic model on the blowout cavity shape created by transversely asymmetric long beams, with Particle-in-Cell (PIC) simulations. The analysis focuses on validating the model's ability to predict the behaviors of different beam profiles in this regime.
Paper: MOPR65
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR65
About: Received: 17 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR66
Progress on the capillary plasma discharge source at UCLA
587
At UCLA, a plasma source using capillary discharge has been developed and studied for its potential use in plasma wakefield experiments at MITHRA and AWA facilities. This compact, 8-cm long source, has the ability to create plasmas covering a wide range of densities, making it suitable for various experiments involving plasma wakefield acceleration (PWFA). With a 3-mm aperture, it can transmit high-aspect ratio beams, and its adjustable density feature allows for a detailed exploration of the shift from linear to nonlinear PWFA stages. In this paper, we will delve into the construction and evaluation of this capillary discharge plasma source, as well as the utilization of an interferometric diagnostic system for measuring plasma density.
Paper: MOPR66
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR66
About: Received: 17 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPR67
Ion-ion collisions in plasma wakefield accelerators
591
The plasma wakefield accelerator, with acceleration gradients ranging from GeV/m to TeV/m, holds promise for propelling particles to high energies in linear colliders. This results in exceptionally bright beams characterized by intense ion-derived focusing, leading to the collapse of plasma ions. The non-uniform ion density triggers robust nonlinear focusing, potentially resulting in undesirable beam emittance growth. Our study extends prior research focused on electron acceleration by investigating ion-ion collisions, studying different collision models emphasizing the near-equilibrium state post-ion collapse utilizing the OSIRIS PIC code. Notably, our findings reveal that parametric excitations arising from plasma non-uniformity have an insignificant impact on phase space diffusion, a crucial insight for optimizing linear colliders.
Paper: MOPR67
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR67
About: Received: 16 May 2024 — Revised: 20 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPR70
Development of inductive high temperature oven (HTO) at the facility for Rare Isotope Beams
602
Many of ion beams generated by the Electron Cyclotron Resonance Ion Source (ECRIS) originate from solid-state materials and undergo a conversion process to transition from a solid to a gaseous state before being introduced into the plasma. Established techniques for thermal evaporation encompass ovens and others. The primary objective is to advance oven technology targeting increased reliability, durability, efficiency, and an expanded temperature range. At the Facility for Rare Isotope Beams (FRIB), a specialized inductive High Temperature Oven (HTO) has been developed to ensure the consistent and reliable production of metallic ion beams. ANSYS simulations have been carried out to maximize the temperature inside the oven and to help select the materials used with the oven based on the analysis on the heat distribution. Off-line tests have shown that the oven operates durably at temperatures close to 2000°C, and on-line tests already demonstrated beam intensity as high as 52 eµA of 238U35+ and 60 eµA of 238U33+. This paper presents and discusses the design features, ANSYS simulations, off-line and on-line test results of the HTO.
Paper: MOPR70
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR70
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPR75
Particle-in-cell modeling of low-temperature plasma ion sources for ion implantation
618
Numerical modeling of low-temperature plasma (LTP) ion sources provides cost-effective techniques for developing and optimizing beam characteristics for ion implantation and other applications, including plasma processing and etching. Particle-in-cell (PIC) models are a powerful tool for simulating plasma formation and dynamics in LTP sources. Beam formation and transport of the beam through extraction optics can benefit from reduced physical models. One can couple a PIC model for plasma chambers with a different transport model in the extraction region. However, this coupling is ad hoc, and it is often not clear that the models are physically consistent with each other. We present an integrated modeling capability that couples plasma chamber modeling with beam formation using the VSim computational framework. We leverage advanced modeling techniques such as energy-conserving PIC and variable meshing to improve simulation performance. We present results for modeling and optimization of beams for ion implantation. Our results show that our integrated models can improve optimization of beam currents, beam uniformity, and emittance for LTP ion sources.
Paper: MOPR75
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR75
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPR76
Studies of photoemission in the high-field regime in an X-band photoemission RF gun
622
A program is underway at the Argonne Wakefield Accelerator (AWA) facility, in collaboration with Euclid Techlabs and Northern Illinois University (NIU), to develop a GV/m-scale photocathode gun, to produce bright electron bunches. The novel X-band (11.7 GHz) photoemission gun (Xgun) is powered by high-power, short RF pulses (9 ns) generated by the AWA drive beam in a wakefield structure. In the first series of experiments, the Xgun demonstrated peak fields of ~400 MV/m on the photocathode surface. As a first step towards achieving a complete understanding of the Xgun’s performance in the high-field regime, we studied the photoemission mechanism by measuring the quantum efficiency (QE) and thermal emittance across a large range of operating fields on the photocathode surface from 60 MV/m to values exceeding 300 MV/m. In this work, we will present the results of our experimental measurements and simulation studies on examining photoemission at high fields on the photocathode surface.
Paper: MOPR76
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR76
About: Received: 20 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPR77
Quest for an optimal spin-polarized electron source for the Electron-Ion Collider
626
Superlattice GaAs photocathodes play a crucial role as the primary source of polarized electrons in various accelerator facilities, including the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson National Laboratory and the Electron-Ion Collider (EIC) at Brookhaven National Laboratory. To increase the quantum efficiency (QE) of GaAs/GaAsP superlattice photocathodes, a Distributed Bragg Reflector (DBR) is grown underneath using metal-organic chemical vapor deposition (MOCVD). There are several challenges associated with DBR photocathodes: the resonance peak may not align with the emission threshold of around 780 nm, non-uniform doping density in the top 5 nm may significantly impact QE and spin polarization, high-temperature heat treatment may lead to interlayer material diffusion, and the number of DBR pairs may not be optimal, affecting both QE and spin polarization. In this paper, we will report our progress in addressing these challenges to hunt for suitable photocathodes for the EIC.
Paper: MOPR77
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR77
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPR78
PHOtocathode Epitaxy and Beam Experiments laboratory at Cornell: current status and future work
630
High-efficiency alkali antimonide photocathodes degrade with little oxidation, making them hard to characterize and test outside their growth chamber. In this proceeding, we report on the design and performance of the PHOtocathode Epitaxy and Beam Experiments (PHOEBE) laboratory at Cornell University, where the growth, characterization, and testing of alkali photocathodes in vacuum has been successfully integrated. The growth of photocathodes is characterized in-situ by measuring the QE and by looking at the photocathode’s reflection high energy electron diffraction (RHEED) pattern. Once the desired photocathode is obtained, it is moved to a storage chamber to collect spectral response data, after which it is moved to the cryogenic emittancediagnostic beamline via a vacuum suitcase. A rapid cathode exchange system in the diagnostic beam can efficiently transfer alkali-antimonide photocathodes to beamline operation with little QE loss. Using this beamline, the mean transverse energy of the photocathode can be measured at various photoexcitation wavelengths in the visible spectrum and sample temperatures within 20 - 300 K.
Paper: MOPR78
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR78
About: Received: 16 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPR79
Demonstration of enhanced quantum efficiency from optical interference in alkali antimonide photocathodes
634
We present measurements of quantum efficiency (QE) modulations in CsSb and Cs3Sb photocathodes that arise from optical interference of reflections from the underlying substrate that has multiple semi-transparent layers. The photocathode films are grown on a cubic silicon carbide layer (3C-SiC) which itself is grown epitaxially on Si(100) during fabrication. We find that the QE modulates by up to a factor of two over a laser wavelength range of 30 nm, and that a modulation peak can be tuned to coincide with a desired laser wavelength by changing the thicknesses of both the photocathode and the silicon carbide layer in the substrate. A model for the QE modulations is derived and fitted to QE measurements of CsSb and Cs3Sb films, which have different indices of refraction, in addition to QE measurements of Cs3Sb films grown on 3C-SiC substrates with two different silicon carbide layer thicknesses. Good agreement is found between the model and measurements, confirming the optical interference effect can be exploited to enhance quantum efficiency at desired visible wavelengths.
Paper: MOPR79
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR79
About: Received: 17 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR80
Alternative negative electron affinity activation studies at HERACLES
638
A new growth chamber at the High ElectRon Average Current for Lifetime ExperimentS (HERACLES) beamline at Cornell has been installed enabling Negative Electron Affinity (NEA) activations of GaAs using Cs-Sb-O and Cs-Te-O recipes. These activation recipes have been shown to be more robust against vacuum poisoning when measured at low voltages and currents. In this proceeding we present charge lifetime measurements of these recipes when operated in a high voltage, high current electron gun.
Paper: MOPR80
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR80
About: Received: 16 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPR81
An overview of spin-polarized photocathode research at Cornell University
642
The development of a robust spin-polarized electron source capable of sustaining mA scale average beam currents in a photoinjector is critical for many future accelerator facilities such as the International Linear Collider (ILC). In this proceeding we overview the several efforts being carried out at Cornell towards this end, including: high current (>1 mA) gun tests of robust activation recipes of GaAs at the HERACLES beamline, the development and demonstration of GaN as a robust spin polarized source and Density Functional Theory (DFT) ab initio studies of alkali-antimonide photocathodes as potential spin polarized electron sources.
Paper: MOPR81
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR81
About: Received: 20 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR82
Chemical robustness enhancement of negative electron affinity photocathodes through cesium-iodide deposition
646
Photocathodes at Negative Electron Affinity (NEA), like GaAs and GaN, allow for efficient production of spin-polarized electrons. When activated to NEA with cesium and an oxidant, they are characterized by an extreme sensitivity to chemical poisoning, resulting in a short operational lifetime. In this work, we demonstrate that deposition of a cesium iodide (CsI) layer can be used to enhance the dark lifetime of both GaN and GaAs photocathodes activated with cesium. The mechanism behind this improvement is investigated using X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) techniques.
Paper: MOPR82
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR82
About: Received: 17 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPR84
Unusual electron emission characteristics of CeB6 cathodes
652
Thermionic electron guns that use borides of lanthanum or cerium as the electron emission surface are widely adopted for electron microscopes due to their high brightness. CeB6 cathodes are known for their high environmental durability and can be used up to a vacuum pressure of 1e-6 Pa. At MHI-MS, our company, we also adopt CeB6 cathodes in the C-band compact accelerating structure units we manufacture, and we have shipped dozens of units so far. As for the cathode assembly, we purchase Vogel-type cathodes and incorporate them into the thermionic electron guns. Before shipping, we bake the entire accelerating structure, including the electron gun, and confirm the electron emission characteristics. Recently, some of the procured cathodes have exhibited abnormal behavior, such as a decrease in electron emission as the vacuum pressure of the electron gun decreases. Analysis of the CeB6 crystal shows no significant differences between the normal and abnormal batches, and the cause is still unknown.
Paper: MOPR84
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR84
About: Received: 13 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPR86
Empirical modeling of the photocurrent time-dependence in co-deposition activation procedures for GaAs photocathodes
656
GaAs-based photocathodes can provide electron beams with high spin-polarization. In order to be used in a photo-gun for high-current applications such as energy-recovery linacs and colliders, the quantum efficiency as well as the lifetime of the photocathode needs to be as high as possible. Both parameters depend on the quality of the thin layer that is applied to the photocathode surface during the so-called activation process in order to create negative electron-affinity conditions for optimal photoemission. Hence, it is of great interest to optimize and standardize this procedure in order to provide the best possible photocathode performance for accelerator applications. For an automatization of the activation process it is necessary to model the photocurrent as a function of time during the process. To this end, activations of bulk-GaAs using Cs and O, conducted at the Photo-CATCH test stand, were analyzed using an empirical model function. This contribution presents the results of the analysis and its implications regarding the influence of the activation process on the performance of the activated photocathode.
Paper: MOPR86
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR86
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPR87
Electron beam dynamics simulations in electron gun and fabrication of cold field emitters by electrochemical etching
660
In this paper, beam dynamics simulations in a compact 200 kV DC electron gun at Tsinghua University are carried out and pm·rad-scale low normalized transverse emittance is obtained in the preliminary results. Small emission areas and low initial electron energies contribute to the generation of beams with low transverse emittance. We used electrochemical etching to fabricate tips for cold field emitters and got several regularly shaped tips with a small radius of curvature of the apex in some attempts. We anticipate that sharp tips in high-gradient electron guns can provide high-quality electron beams for different applications, e.g. high spatial resolution electron microscopy.
Paper: MOPR87
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR87
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPR89
Framework for a multiphysics model of optical field emission from extended nanostructures
664
Laser-field emission, or optical field emission, is a process that can produce electron beams with high charge density and high brightness with ultrafast response times. Using an extended nanostructure, such as a nanoblade, permits plasmonic field enhancement up to 80 V/nm with an incident ultrafast laser of wavelength 800 nm. Stronger ionizing fields lead to higher current densities, so understanding how this field is attained will aid in further increasing brightness. In this paper we lay the framework to study the nanoblade system thermomechanically and plasmonically. We show that, in the moving frame following the laser driver, a steady state is reached, allowing us to reduce the computational complexity of the multiphysics calculation. We derive Maxwell's equations and the current dynamical equation for the steady state in such a moving frame. We also derive the eigenproblem for finding plasmonic modes in the structure with a nonlinear dielectric. The planned calculations to come will allow us to predict peak attainable fields and optimal experimental parameters. We leave off with a discussion of directions for numerical implementation.
Paper: MOPR89
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR89
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPR91
Particle motion in spatio-spectrally iso-diffracting ultrabroadband pulsed beams
672
An analytical form is derived using the Faddeeva function to represent terahertz-frequency pulses generated by optical rectification of ultrashort laser pulses. Spectra of these pulses can be described by a Gaussian fall-off at high frequencies and a power-law as DC is approached. A set of pulsed beams based on this form is also derived for the special case of propagation-invariant spatio-temporal coupling (iso-diffracting). Motion of charged particles in these pulsed beams is considered analytically and numerically and energy gain is computed and compared with ponderomotive force laws. Particle motion in more complex pulsed-beam fields is also considered.
Paper: MOPR91
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR91
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR92
Evaluation of ultrafast THz near-fields for electron streaking
675
THz-frequency accelerating structures could provide the accelerating gradients needed for compact next generation particle accelerators. One of the most promising THz generation techniques for accelerator applications is optical rectification in lithium niobate using the tilted pulse front method. However, accelerator applications are limited by losses during transport and coupling of THz radiation to the acceleration structure. Applying the near-field of the lithium niobate source directly to the electron bunch removes losses due to transport and coupling, yielding a simplified and efficient system. Using electro-optic sampling we have reconstructed the full temporal 3D THz near-field close to the lithium niobate emission face and shown that it can be controlled by manipulating the generation setup. Analysis of the results of this measurement shows an estimated peak field strength of 86 MV/m. A future THz near-field electron streaking experiment is currently planned as a first test of manipulating an electron bunch with the THz near field. Analysis for this planned experiment has yielded an estimated THz near-field kick strength of 23 keV.
Paper: MOPR92
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR92
About: Received: 15 May 2024 — Revised: 28 May 2024 — Accepted: 28 May 2024 — Issue date: 01 Jul 2024
MOPR93
Neutron production using compact linear electron accelerators
678
Many reactor-based neutron sources are planned to shut down in the near future, and this is despite the increasing demand for neutron beamlines for a wide range of scientific and industrial applications. Consequently, compact accelerator-based neutron sources arise as a competitive alternative that could meet the need for medium-flux fission or spallation sources. In this work, we explore the performance of compact electron accelerators as neutron drivers and propose a preliminary target design for an X-band electron-linac-based neutron source.
Paper: MOPR93
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR93
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS12
Axially symmetric e-lens based on McMillan map
721
In this work, we investigate the transverse dynamics of a single particle in a model integrable accelerator lattice, based on a McMillan axially symmetric electron lens. Although the McMillan e-lens has been considered as a device potentially capable of mitigating collective space charge forces, some of its fundamental properties have not been described yet. The main goal of our work is to close this gap and understand the limitations and potential of this device. We classify possible regimes with stable trajectories and provide set of canonical action-angle variables, along with an evaluation of the dynamical aperture, Poincar\'e rotation numbers as functions of amplitudes, and spread in nonlinear tunes.
Paper: MOPS12
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS12
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPS21
Update on the beam-induced heating and thermal analysis for the EIC vacuum chamber components
755
One of the challenges of designing the Electron-Ion Collider (EIC) is to mitigate beam-induced heating due to the intense electron and hadron beams. Heating of the Electron Storage Ring (ESR) vacuum chamber components is mainly due to beam-induced resistive wall loss and synchrotron radiation. For the Hadron Storage Ring (HSR) components, heating is mainly due to resistive wall loss because of the large radial offset, electron cloud formation, and heat conduction from room temperature to cryo-components. In this paper, we provide an update on the beam-induced heating and thermal analysis for some EIC vacuum chamber components including the RF-fingers module of HSR cryogenic interconnect assembly. In addition, we provide simulation update for the HSR snake BPM, and abort kicker along with the change in ESR vacuum chamber profile. Similar analysis for other HSR and ESR components are available in Ref.~\cite{sangroulalocalized_NAPAC22, sangroula2023beam}. Our approach for thermal analysis involves calculating resistive wall losses using CST, evaluating heat loss due to synchrotron radiation and electron cloud formation and incorporating these losses into ANSYS for finding the temperature distribution.
Paper: MOPS21
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS21
About: Received: 16 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS22
Resistive wall heating and thermal analysis of the EIC HSR beam screen
759
The Electron-Ion Collider (EIC) utilizes the existing Relativistic Heavy Ion Collider (RHIC) rings as a Hadron Storage Ring (HSR) with some modifications. However, this presents significant challenges, primarily due to beam-induced Resistive Wall (RW) heating resulting from a larger radial offset and shorter EIC bunches (up to 10 times shorter than RHIC). Additionally, the formation of an electron cloud further complicates matters. To address these issues and operate the HSR effectively, this paper focuses on the RW heating and thermal analysis of the EIC HSR beam screen. Our approach involves the insertion of a copper-coated stainless steel beam screen with cooling channels and longitudinal slots. We conducted a detailed thermal analysis, assessing piecewise RW losses around the beam screen's profile due to an offset beam, employing the 3D commercial code CST. These losses, along with realistic boundary conditions, were then integrated into another code, ANSYS, to determine the thermal distribution.
Paper: MOPS22
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS22
About: Received: 18 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPS27
An open-source Python tool for the Maxwell eigenvalue problem and multipacting analysis in axisymmetric elliptical cavity structures
771
Multipacting is a phenomenon arising from the emission and subsequent multiplication of charged particles in accelerating radiofrequency (RF) cavities, which can limit the achievable RF power. Predicting field levels at which multipacting occurs is crucial for optimizing cavity geometries. This paper presents a new open-source Python code for analyzing multipacting in 2D axisymmetric cavity structures. The code leverages the NGSolve framework to solve the Maxwell Eigenvalue Problem (MEVP) to obtain the cavity's resonant modes' electromagnetic fields. The relativistic Lorentz force equation governing the motion of charged particles is then integrated using the fields within the cavity. Benchmarking against existing multipacting analysis tools is performed to validate the code's accuracy and efficiency. The open-source nature of the code fosters further development and customization for specific applications.
Paper: MOPS27
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS27
About: Received: 12 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPS36
Intrabunch motion in the presence of mode coupling
798
The intrabunch motion for independent longitudinal or transverse beam oscillation modes has been explained analytically for impedance driven bunched-beam coherent instabilities already several decades ago by Laclare and they have been observed in many measurements and simulations. These oscillation patterns do not depend on the bunch intensity, they are head/tail symmetric and they exhibit a number of nodes equal to the radial mode number. However, in many measurements and simulations of transverse beam instabilities (due to impedance only, impedance and beam-beam, impedance and space charge, or electron cloud), asymmetric patterns are observed depending on the bunch intensity. The latter can be described theoretically considering the interaction between several modes, i.e. mode coupling, which explains why and how different kinds of asymmetric intrabunch signals can be observed. In this paper, the intrabunch motion in the presence of mode coupling is explained first without maths and then with maths, considering the case of a bunch interacting with a transverse impedance, using the GALACTIC Vlasov solver.
Paper: MOPS36
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS36
About: Received: 02 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
MOPS39
Formulas of coherent synchrotron radiation induced microbunching instability in an arbitrary four-dipole chicane bunch compressor
806
Almost all linac-based free-electron laser (FEL) facilities have employed a symmetric three- or four-dipole chicane to compress the electron beam in order to achieve a kA-level bunch current. The achromatic C-type chicane has been widely used in present linac-FEL facilities. Coherent synchrotron radiation (CSR) induced microbunching instability (MBI) can be an issue in the chicane design. Recently a novel design of non-symmetric four-dipole chicane has been proposed to effectively mitigate the CSR-induced emittance growth. In this work we derive an analytical formula of the CSR-induced microbunching gain in a generic four-dipole chicane based on the iterative approach. The formulas have been benchmarked against semi-analytical Vlasov calculation, applied for a quick estimate of CSR-induced MBI for a generic four-dipole achromatic chicane beamline, and can be used to verify the effectiveness of suppressing MBI in a non-symmetric S-type four-dipole bunch compressor chicane.
Paper: MOPS39
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS39
About: Received: 03 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPS40
Microbunching threshold manipulation by a corrugated structure impedance at KARA
810
Two parallel corrugated plates can be used to manipulate the impedance of an electron storage ring such as the KIT storage ring KARA (KArlsruhe Research Accelerator). This impedance manipulation structure opens up the possibility to eventually control the electron beam dynamics and the emitted coherent synchrotron radiation (CSR). In this contribution, we present the impedance that is most effective to manipulate the threshold of the microbunching instability for different machine settings. Furthermore, it will be shown, how the resonance frequency of this impedance is related to the spectrum of the substructures in the electron bunches.
Paper: MOPS40
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS40
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS42
Start-to-end simulations of microbunching instability based on optimized velocity bunching in linac-driven FELs
817
The microbunching instability (MBI) driven by beam collective effects can cause significant electron beam quality degradation in advanced X-ray free electron lasers. Typically, multiple stage magnetic bunch compressors used to generate high peak current electron beam will dramatically amplify the microbunching instability. In this paper, by redesigning the solenoid elaborately and adopting a dual-mode buncher cavity with the third harmonic mode used to correct the RF curvature, in combination with the evolutionary many-objective beam dynamics optimization, it is potential for the electron beam to be further compressed in velocity bunching (VB) process. Therefore, a VB plus one bunch compressor could be a promising alternative scheme to achieve moderate peak current beam for X-ray FELs. Start-to-end simulations based on the Shanghai high-repetition-rate XFEL and extreme light facility proves the feasibility of the scheme in suppressing the additional MBI gain due to multi-stage magnetic bunch compressors.
Paper: MOPS42
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS42
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPS47
Unifying coherent synchrotron radiation wakefield and classical radiation reaction
825
We develop an alternative theory of coherent synchrotron radiation (CSR) wakefield using the transverse field solution of Maxwell equations in angular domain. This approach allows us to retain only the radiative interaction between particles and cure the frequently encountered divergence in retarded potentials. We analyze the classical radiation reaction force and mass renormalization induced by the CSR self-field. Futhermore, we illustrate our theory by explicitly calculating the steady-state CSR wakefield of a wiggler.
Paper: MOPS47
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS47
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPS51
Measurements and simulations of the e-cooling performance in ELENA
836
Understanding and optimizing the electron cooling performance is essential to ensure high-brightness antiproton beams at the Extra Low Energy Antiproton (ELENA) ring at CERN. This paper presents measurements and simulations of the electron cooling performance in ELENA. The simulations are obtained using the Parkhomchuk model for electron cooling recently implemented in the Xsuite simulation framework. The studies focus on the impact of the electron-beam current, electron-beam size, magnetic field quality, and electron-/pbar-beam trajectory overlap on cooling performance. Notably, the results indicate the maximum magnetic field imperfection that would still provide adequate cooling in ELENA.
Paper: MOPS51
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS51
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPS58
First-principle simulations of a laser-assisted bunch compression scheme
852
High brightness electron beams with high peak current are critical to reducing the size of XFEL. A promising approach consists in combining low emittance beam generated high-frequency photoinjector with a laser-assisted bunch compression scheme. Such a compression consists in using an infrared laser to modulate the electron beam energy in a planar undulator and a low R56 chicane to compress these modulations and produced a micro-bunched beam. We present first-principle simulations of this compression process including the impact of coherent synchrotron radiation (CSR) on the beam dynamics. These simulations were performed using the large-scale self-consistent LW3D code for two compression configurations under study for compact XFEL designs.
Paper: MOPS58
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS58
About: Received: 24 May 2024 — Revised: 25 May 2024 — Accepted: 28 May 2024 — Issue date: 01 Jul 2024
MOPS62
Generation of attosecond electron bunches through terahertz regulation
863
Obtaining ultrashort electron bunches is the key to the studies of ultrafast science, yet second and higher order nonlinearities limits the bunch length to a few femtoseconds after compression. Traditional regulation methods using rf higher order harmonics have already optimized the bunch length to sub-fs scale, yet the energy loss and rf jitter are not negligible. In this paper we demonstrate the second order regulation with THz pulses through a dielectric-loaded wave-guide. Simulations suggest that with higher order correction, the MeV electron bunches with tens of fC charges can be compressed to a 679 attoseconds rms and the second order distortion can be compensated. The transverse beam size is also optimized to 16.8 um rms. This scheme is feasible for a wide range of electron charges. The relatively short bunch length is expected to find a better time resolution in UED, UEM and other ultrafast, time-resolved studies.
Paper: MOPS62
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS62
About: Received: 11 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPS63
Research on spatial alignment of laser and electron beam in the generation of ultra-short electron pulses by laser modulation
866
The utilization of laser modulation techniques shows potential in producing sub-femtosecond electron beams within photoinjector electron guns. The precise spatial alignment between the modulated laser and electron beam is crucial for the stable emission of sub-femtosecond electron beams. In practical applications, inevitable lateral positional fluctuations are present in both the modulated laser and electron beam pulses, resulting in uneven and suboptimal modulation effects of the laser on the electron beam. Photocathode electron guns commonly utilize solenoid focusing for transverse electron beam concentration, inducing transverse phase space coupling and causing the laser-induced transverse jitter in the electron gun to not accurately reflect the transverse jitter of the electron beam. This study seeks to employ coherent lasers and devise a solenoid coil to disentangle the transverse phase space of the electron beam, ensuring that the transverse jitter of the electron beam aligns with the jitter of the modulated laser at the focal point.
Paper: MOPS63
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS63
About: Received: 10 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPS69
Harnessing machine learning for the optimal design of ILC e-driven positron source
886
The International Linear Collider (ILC) is a next-generation electron-positron collider designed to operate at center-of-mass energies ranging from 250 GeV to 1 TeV, providing opportunities for exploring physics beyond the Standard Model. A critical component of the ILC is the E-driven positron source, which requires sophisticated technology to produce large quantities of positrons. Traditional accelerator design methods involve sequential optimization, which is inefficient and challenging for achieving global optimization. This study introduced the use of the Tree-structured Parzen Estimator (TPE) algorithm, a black-box optimization method, to improve the design efficiency of the ILC E-driven positron source. By implementing the TPE algorithm using Optuna, we optimized up to 8 parameters, achieving a positron capture efficiency of 1.42, significantly higher than the 1.20 efficiency obtained through manual optimization. This substantial improvement is expected to meet the safety standards for target destruction. The optimization process was also expedited, reducing the time from about a week to approximately half a day. These results demonstrate the potential of machine learning techniques in accelerator design, offering a more comprehensive global optimization by exploring a broader parameter space and avoiding local minima.
Paper: MOPS69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS69
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPS72
Solving the Orszag-Tang vortex magnetohydrodynamics problem with physics-constrained convolutional neural networks
897
The 2D Orszag-Tang vortex magnetohydrodynamics (MHD) problem is studied through the use of physics-constrained convolutional neural networks (PCNNs). The density and the magnetic field are forecasted, and we also predict magnetic field given the velocity field of the fluid. We examined the incorporation of various physics constraints into the PCNNs: absence of magnetic monopoles, non-negativity of density and use of only relevant variables. Translation equivariance was present from the convolutional architecture. The use of a residual architecture and data augmentation was found to increase performance greatly. The most accurate models were incorporated into the simulation, with reasonably accurate results. For the prediction task, the PCNNs were evaluated against a physics-informed neural network (PINN), which had the ideal MHD induction equation as a soft constraint. The use of PCNNs for MHD has the potential to produce physically consistent real-time simulations to serve as virtual diagnostics in cases where inferences must be made with limited observables.
Paper: MOPS72
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS72
About: Received: 13 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS73
Utilizing neural networks to speed up coherent synchrotron radiation computations
901
Coherent synchrotron radiation has a significant impact on electron storage rings and bunch compressors, inducing energy spread and emittance growth in a bunch. While the physics of the phenomenon is well-understood, numerical calculations are computationally expensive, severally limiting their usage. Here, we explore utilizing neural networks (NNs) to model the 3D wakefields of electrons in circular orbit in the steady state condition. We demonstrate that NNs can achieve a significant speed-up, while also accurately reproducing the 3D wakefields. NN models were developed for both Gaussian and general bunch distributions. These models can potentially aid in the design and optimization of accelerator apparatuses by enabling rapid searches through parameter space.
Paper: MOPS73
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS73
About: Received: 13 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPS74
Accelerator system parameter estimation using variational autoencoded latent regression
905
A particle accelerator is a time-varying complex system whose various components are regularly perturbed by external disturbances. The tuning of the accelerator can be a time-consuming process involving manual adjustment of multiple components, such as RF cavities, to minimize beam loss due to time-varying drifts. The high dimensionality of the system (~100 amplitude and phase RF settings in the LANSCE accelerator) makes it difficult to achieve optimal operation. The time-varying drifts and the dimensionality make system parameter estimation a challenging optimization problem. In this work, we propose a variational autoencoded latent regression (VAELR) model for robust estimation of system parameters using 2D unique projections of a charged particle beam's 6D phase space. In VAELR, VAE projects the phase space projections into a lower-dimensional latent space, and a dense neural network maps the latent space onto the space of system parameters. The trained network can predict system parameters for unseen phase space projections. Furthermore, VAELR can generate new projections by randomly sampling the latent space of VAE and also estimate the corresponding system parameters.
Paper: MOPS74
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS74
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPS81
Implementing betatron radiation for beam diagnostics studies
917
Betatron radiation is a form of synchrotron radiation emitted by moving or accelerated electron or positron-like charged particles. As a valuable tool it can provide useful information about their trajectories, momentum and acceleration. It has good potential as a novel non-destructive diagnostic for laser-driven plasma wakefield acceleration (LWFA) and beam-driven plasma wakefield acceleration (PWFA). Since information about the properties of the beam is encoded in the betatron radiation, measurements using the Maximum Likelihood Estimation (MLE) method, rich information about the beam parameters (beam spot size, emittance, charge, energy etc.) can be extracted. Machine learning (ML) techniques can then be applied to improve the accuracy of these measurements. It has already been observed that betatron radiation can give an insight into the change in plasma density. The QUASAR Group, based at the Cockcroft Institute on Daresbury Sci-Tech campus, is planning to build on and expand an existing collaboration with UCLA and also to apply the technique for the AWAKE experiment at CERN. In this work, a hybrid ML-MLE approach is attempted to optimize the use of these diagnostics and obtain a deep insight into the beam’s parameters e.g. beam spot sizes where ML and MLE individually have their limitations.
Paper: MOPS81
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS81
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
TUBD1
From RHIC to EIC hadron storage ring - overview of the engineering challenges
951
The Electron Ion Collider (EIC) Hadron Storage Ring (HSR) will reuse most of the existing hardware from the RHIC rings. However, extensive modifications will have to be performed in preparation for the new accelerator parameters and performance required by EIC. The beam vacuum chamber will have to be upgraded and new beam position monitors (BPM) implemented to account for the higher beam intensity and shorter EIC hadron bunches. The RF system will also need to be upgraded and include new cavities to drive the new bunch parameters. In some straight sections, existing superconducting magnets will have to be reshuffled and their cold powering scheme modified to accommodate the new accelerator lattice. The hadron injection scheme will also be modified to accommodate three time more bunches and the machine protection system will need to include new collimators. This paper aims to give an overview of the engineering modifications required to turn RHIC into the EIC HSR.
Paper: TUBD1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUBD1
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
TUCN3
Results from CXLS commissioning
981
The Compact X-ray Light Source (CXLS) is a compact source of femtosecond pulses of x-rays that is now commissioning in the hard x-ray energy range 4-20 keV. It collides the beams from recently developed X-band distributed-coupling, room-temperature, standing-wave linacs and photoinjectors operating at 1 kHz repetition rates and 9300 MHz RF frequency, and recently developed Yb-based lasers operating at high peak and average power to produce fs pulses of 1030 nm light at 1 kHz repetition rate with pulse energy up to 200 mJ. These instruments are designed to drive a user program in time-resolved x-ray studies such as SAXS/WAXS, XES and XAS, femtosecond crystallography as well as imaging. The different technical systems also act as prototypes for the more advanced CXFEL discussed elsewhere in these proceedings. We present the performance of the CXLS technical components and initial x-ray results.
Paper: TUCN3
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUCN3
About: Received: 20 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC06
Dynamic aperture of the RCS during bunch merges
1003
The Rapid Cycling Synchrotron (RCS) of the Electron Ion Collider (EIC) will be used to accelerate polarized electrons from 400 MeV to a top energy of 5, 10, or 18 GeV before injecting into the Electron Storage Ring. At 1 GeV, the RCS will perform a merge of two bunches into one, adding longitudinal dynamics that effects the dynamic aperture, depending on the merge parameters. In this paper, results for different merge models will be compared, as well as finding the relationship between the merge parameters of the RCS and its dynamic aperture.
Paper: TUPC06
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC06
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC16
Estimates of the recombination rate for the strong hadron cooling system in the EIC
1040
The strong hadron cooling system (SHC) for the electron-ion collider (EIC) consists of the modulator, the microbunching amplifier and the kicker section. In the modulator and the kicker section, the electrons are co-moving with the protons. If the relative velocity of an electron with respect to a proton is small enough, it can be captured by the proton and the resulting neutral particle, i.e. a hydrogen atom, will deviate from the designed trajectory and get lost around the cooling section. Since the probability of a proton capturing an electron depends on the relative velocity between them, one can align the energy of the two beams based on the number of hydrogen atoms detected by a recombination monitor. In this work, we estimate the rate at which the hydrogen atoms produced by the recombination process for the SHC in EIC.
Paper: TUPC16
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC16
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPC18
Simulations of coherent electron cooling with varied beam parameters
1043
Coherent electron cooling (CeC) is a novel technique for rapidly cooling high-energy, high-intensity hadron beam. Plasma cascade amplifier (PCA) has been proposed for the CeC experiment in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Cooling performance of PCA based CeC has been predicted in 3D start-to-end CeC simulations using code SPACE. The dependence of the cooling rate on the electron beam parameters has been explored in the simulation studies.
Paper: TUPC18
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC18
About: Received: 30 Apr 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPC19
High-current DC gun for low energy RHIC cooler project
1047
Electron cooling of ion beams employing RF-accelerated electron bunches was successfully used for the RHIC physics program in 2020 and 2021. Electron cooler LEReC uses a high-voltage photoemission electron gun with stringent requirements for beam current, beam quality, and stability. The electron gun has a photocathode with a high-power fiber laser, and a novel cathode production, transport, and exchange system. It has been demonstrated that the high-voltage photoemission gun can continually produce a high-current electron beam with a beam quality suitable for electron cooling. We describe the operational experience with the LEReC dc photoemission gun in RHIC and discuss the important aspects needed to achieve the required beam current, beam quality, and stability. We also present recent gun tests in which stable operation at 50 mA CW beam current was established, as well as future plans.
Paper: TUPC19
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC19
About: Received: 08 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPC30
Active control of the energy chirp of a relativistic electron beam at the Argonne Wakefield Accelerator
1068
A very high electron peak current is needed in many applications of modern electron accelerators. To achieve this high current, a large energy chirp must be imposed on the bunch so that the electrons will compress when they pass through a chicane. In existing linear accelerators (LINACs), this energy chirp is imposed by accelerating the beam off-crest from the peak fields of the RF cavities, which increases the total length and power requirements of the LINAC. A novel concept known as the Transverse Deflecting Cavity Based Chirper (TCBC) [1] can be used to actively impose a large energy chirp onto an electron beam in an accelerator, without the need for off-crest acceleration. The TCBC consists of 3 transverse deflecting cavities, which together impose an energy chirp while cancelling out the transverse deflection. An experiment is being developed to demonstrate this concept at the Argonne Wakefield Accelerator (AWA) facility. Here we explain the concept, show preliminary simulations of the experiment, and report on progress related to implementation of the experiment at AWA.
Paper: TUPC30
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC30
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPC34
Magnetic compression method for macro pulses of relativistic electron beam
1074
We developed a magnetic compression method for relativistic electron beam macro-pulses. Our device, with a significantly larger transfer function R56 compared to the classical chicane structure, enables nanosecond-scale compression of relativistic electron pulses using a compact apparatus measuring just a few meters. This paper introduces the principles of this compression method and presents the results of dynamic simulations.
Paper: TUPC34
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC34
About: Received: 13 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
TUPC43
Optimization of cooling distribution of the EIC SHC cooler ERL
1104
The Electron-Ion Collider (EIC) Hadron Storage Ring (HSR) will use strong hadron cooling to maintain the beam brightness and high luminosity during long collision experiments. An Energy Recovery Linac is used to deliver the high-current high-brightness electron beam for cooling. For the best cooling effect, the electron beam requires low emittance, small energy spread, and uniform longitudinal distribution. In this work, we simulate and optimize the longitudinal laser-beam distribution shaping at the photo-cathode, modeling space charge forces accurately. Machine parameters such as RF cavity phases are optimized in conjunction with the beam distribution using a genetic optimizer. We demonstrate the improvement to the cooling distribution in key parameters.
Paper: TUPC43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC43
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC45
A preliminary feasibility study on multi-cavity cryomodule integration for the Electron Ion Collider energy recover linac cooler
1111
The Electron-Ion Collider (EIC) is a cutting-edge accelerator designed to collide highly polarized electrons and ions. For enhanced luminosity, the ion beam is cooled via an electron beam sourced from an energy recovery linac (ERL). The current ERL design accommodates one RF cavity per cryomodule, presenting both beam transport and cost-related challenges. This study investigates the feasibility of reducing the cavity size to accommodate two cavities within a single cryomodule. We analyze two compact cavity design options through frequency scaling, assuming constant loaded quality factor Q and R/Q scaling proportional to the square of the frequency ratio. Our analytical and tracking Beam BreakUp (BBU) model predicts the threshold current for each option. While a smaller cavity footprint is advantageous, maintaining sufficient damping of Higher Order Modes (HOMs) is crucial. We compare the HOM damping effectiveness of the proposed compact design to the existing configuration, which achieves sufficient damping within a slightly larger footprint.
Paper: TUPC45
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC45
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC53
A left-handed helical snake for the HSR
1126
The Electron Ion Collider calls for polarized proton and helion beams on polarized electron beam collisions. To preserve polarization of polarized hadron beams, six full helical snakes will be installed. As there are currently 4 snakes in RHIC, the remaining two snakes will be made from existing rotator magnet coils. The rotator magnets are made from both right handed and left handed helicities. In order for a sufficient stock of spare coils, one snake will be made of left handed coils. Simulations using zgoubi show the left handed snake has sufficient range to provide the desired snake precession axes for helions and protons with the existing power supplies.
Paper: TUPC53
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC53
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC79
Future upgrades for GANIL
1199
We will present the plans and ideas for the next upgrades as discussed for the GANIL-SPIRAL2 installation in France. Recently, a report "French roadmap for Nuclear, Particle, and Astroparticle physics, along with associated technical developments and applications." were produced. It particularly focused to “The future of GANIL”. This was further enriched through extensive discussions by an international expert committee led by Michel SPIRO. These endeavors aim to push the boundaries of research capabilities at GANIL-SPIRAL2 during the next decades. Since the starting up in 1983, 40 years ago, successful exploitation with stable beams at the cyclotrons of GANIL, the laboratory has continuously evaluated and enhanced its capabilities. The latest evolution was the starting up of the SPIRAL2 facility. Today GANIL, with its state-of-the-art installations, including cyclotrons, a linear accelerator, and experimental areas, presents unique opportunities for cutting-edge research. The next upgrades under discussion are to be presented. Involving increasing beam intensities, exploring new exotic nuclei. Endeavors that aim to push the boundaries of research capabilities at GANIL-SPIRAL2 for the next decades.
Paper: TUPC79
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC79
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
TUPC80
Radiation to electronics studies for CERN gamma factory-proof of principle experiment in SPS
1202
The Physics Beyond Colliders is a CERN exploratory study aimed to fully exploit the scientific potential of its accelerator complex. In this initiative, the Gamma Factory experiment aims to produce in the Large Hadron Collider (GF@LHC) high-intensity photon beams in the energy domain up to 400 MeV. The production scheme is based on the collisions of a laser with ultra-relativistic atomic beam of Partially Stripped Ions (PSI) circulating in a storage ring. The collision results in a resonant excitation of the atoms, followed by the spontaneous emission of high-energy photons. A Proof of Principle (PoP) experiment is being planned to study the GF scheme generating X-rays, in the range of keV, from lithium-like lead PSI stored at the CERN Super Proton Synchrotron (SPS). GF-PoP has undergone a series of exhaustive radiation effect studies in view of Radiation to Electronics (R2E) risks. With the use of FLUKA Monte Carlo code, the radiation environment in the laser room and its premises has been estimated during proton and PSI runs. Recorded data from beam instruments has been used to appropriately scale the computed results and to verify the compliance with general R2E limits.
Paper: TUPC80
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC80
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
TUPC81
Characterization of radiation damages to positron source materials
1206
The secondary beam production target at future positron sources at the Continuous Electron Beam Accelerator Facility (CEBAF), the International Linear Collider (ILC) or the Future Circular Collider (FCC), features unprecedented mechanical and thermal stresses which may compromise sustainable and reliable operation. Candidate materials are required to possess high melting temperature together with excellent thermal conductivity, elasticity and radiation hardness properties. In order to substantiate the material choice for the CEBAF and ILC positron sources, the response of candidate materials such as titanium alloys, tungsten, and tantalum to electron beam irradiation was experimentally investigated. CEBAF and ILC expected operating conditions were mimicked using the 3.5 MeV electron beam of the MAMI facility injector. The material degradations were precisely analyzed via high energy X-ray diffraction at the HEMS beamline operated by the Helmholtz-Zentrum Hereon at the PETRA III synchrotron facility. This work reports the results of these measurements and their interpretation.
Paper: TUPC81
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC81
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC83
A high-power positron converter based on a recirculated liquid metal in-vacuum target
1210
An effective high-power positron converter for electron linear accelerators is not currently available from industry. A commercial source would allow research institutes to have ready access to high-brightness positrons for a wealth of material science, nuclear, particle, and accelerator physics projects. Xelera Research LLC has designed, built, and tested a prototype free-surface liquid-metal (GaInSn) jet converter. Free-surface liquid-metal jets allow for significantly greater electron beam power densities than are possible with solid targets. Higher power densities lead to greater positron production and, importantly, allow continuous wave (CW) operation. A modified version of the GaInSn converter prototype is planned to be constructed and tested at the Thomas Jefferson National Accelerator Facility.
Paper: TUPC83
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC83
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
TUPC84
Novel positron beam generation based on Shanghai Laser Electron Gamma Source
1214
The Shanghai Light Source has been operated since 2009 to provide synchrotron radiation to 40 beamlines of the electron storage ring at a fixed electron energy of 3.5 GeV. The Shanghai Laser Electron Gamma Source (SLEGS) is approved to produce energy-tunable gamma rays in the inverse Compton slant-scattering of 100 W CO2 laser on the 3.5 GeV electrons as well as in the back-scattering. SLEGS can produce gamma rays in the energy range of 0.66 – 21.7 MeV with flux of 1e+5 – 1e+7 photons/s*. A positron source based on SLEGS is designed to produce positron beams in the energy range of 3 – 16 MeV with a flux of 1e+5 /s and energy resolution of ~7% with an aperture of 10 mm collimator. The positron generated has been simulated by GEANT4, uses a SLEGS gamma injected into a single-layer target, and a dipole magnet deflect positrons. Based on the energy-tunable SLEGS gamma rays, the optimized parameters at each gamma energy were simulated to obtain an energy-tunable positron source. We have confirmed positron generation in the commissioning. We plan to construct the positron source in the summer of 2024. We present the positron source based on results of simulation and test measurements.
Paper: TUPC84
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC84
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPG40
Status of beam commissioning at NanoTerasu
1320
NanoTerasu is a new 3 GeV compact soft X-ray (SX) light source having a circumference of 349 m constructed in Japan. The lattice structure is a type of multi-bend achromat with design emittance values of 1.14 nm·rad and 10 pm·rad, respectively. A target stored current is set to 400 mA to provide a high coherence and highly brilliant light from extreme ultraviolet to SX range. The injector LINAC commissioning was started in April 2023. After first 10 days, the beam energy successfully reached 3 GeV with the designed emittance. The 3 GeV C-band full-energy injector LINAC enables the extension to the SX free electron laser in the future. The storage ring beam commissioning was started on June 8th. We achieved the off-axis beam injection just adjusting beam injection trajectory from the beginning of the beam commissioning. As a result of the precise alignment of the magnets, the injected beam turned around 300 turns without the supply of RF power and the adjustment of the steering magnets on the first day of the commissioning. The stored current was reached 300 mA with top-up beam injection in November. The user operation will be started in April 2024. The creation of COD and tune correction tables for the insertion device is also in progress including non-linear magnetic field correction. We try to start the user operation with designed 400 mA top-up beam injection. The status of beam commissioning will be presented.
Paper: TUPG40
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG40
About: Received: 12 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPG42
The status of the X-ray beam position monitor in the TPS front end
1327
The X-ray beam position monitors (XBPMs) installed in the front end system of the Taiwan Photon Source (TPS) is discussed in this article. This XBPM has an Advanced Photon Source (APS) blade type. Calibration has been finished for most XBPMs in the front end of the insertion device beamline. The stability and resolution of the XBPMs will be introduced in the article. The problems encountered during functioning will also be men-tioned.
Paper: TUPG42
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG42
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
TUPG43
Light source top-up through direct generation of electron beam based on LPA technology
1330
Laser plasma acceleration (LPA) technology is advancing day by day, getting ready for user facility applications. LPA might be applicable to a generation of electron beams directly within the light-source storage-ring vacuum chamber. Typical injector of the light source facility consists of linac and synchrotron booster (or simply a full energy linac). It can be replaced by a laser plasma cell and a driving laser system that can generate multi-GeV electron beams through so-called self injection. The electron beam out of plasma cell has typically a large energy spread. In this application, however, we do not require small energy spread since the storage ring can accept off-energy electrons of up to ±5% or so. It can also have a transverse angular acceptance of a few hundred micro radian. Therefore, a large fraction of generated electrons can be eventually accepted by the storage ring. LPA system, which replaces the conventional injector, may contribute to significant energy saving.
Paper: TUPG43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG43
About: Received: 10 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPG50
Echo-enabled harmonic generation at the DELTA storage ring
1354
Echo-enabled harmonic generation (EEHG) has been proposed as a seeding method for free-electron lasers but can also be employed to generate ultrashort radiation pulses at electron storage rings. With a twofold laser-electron interaction in two undulators, each followed by a magnetic chicane, an electron density pattern with a high harmonic content is produced, which gives rise to coherent emission of radiation at short wavelengths. The duration of the coherently emitted pulse is given by the laser pulse lengths. Thus, the EEHG pulse can be three orders of magnitude shorter and still more intense than conventional synchrotron radiation. At the 1.5-GeV synchrotron light source DELTA at TU Dortmund University, the worldwide first implementation of EEHG at a storage ring was achieved by reconfiguring an electromagnetic undulator. The paper reviews the experimental setup and describes the present status of the project.
Paper: TUPG50
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG50
About: Received: 15 May 2024 — Revised: 13 Jun 2024 — Accepted: 13 Jun 2024 — Issue date: 01 Jul 2024
TUPG51
Single-electron experiments at the DELTA storage ring
1358
Scraping the beam in an electron storage ring while counting photons of synchrotron radiation is a well-known technique to produce a beam of a single or a few electrons which enables new experimental opportunities compared to standard accelerator physics. Synchrotron radiation is usually described as an electromagnetic wave in the frame of classical electrodynamics. The emission of photons by a single electron, on the other hand, reveals the quantum nature of synchrotron light. The statistical properties of photons contain additional information, which can be used for beam diagnostics purposes. The paper describes the experimental setup and first single-electron measurements at the 1.5-GeV synchrotron radiation source DELTA at TU Dortmund University.
Paper: TUPG51
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG51
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
TUPG53
Initial status report on BNL ATF AE131 experiment harmonic nonlinear inverse Compton scattering
1365
Recent progress of basic study on Harmonic nonlinear Compton scattering in Brookhaven National Laboratory Accelerator Test Facility (BNL ATF) will be reported. Experiment is conducted by counter collision of a multi TW CO2 laser and 60-70 MeV electron beam having 300-600 pC of charge per pulse. Experiment AE131 is intended for two aspects of experimental demonstrations. A: Nonlinear bi harmonic effect seen in external lasers having shorter wavelength such as Nd:YAG laser induced by a long wavelength intense CO2 laser at scattered photon energy of 100 keV range. B: Detailed study on the harmonic radiation induced by circularly polarized multi TW CO2 laser which potentially contain the Orbital Angular Momentum at photon energy of 10 keV range.
Paper: TUPG53
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG53
About: Received: 15 May 2024 — Revised: 27 May 2024 — Accepted: 27 May 2024 — Issue date: 01 Jul 2024
TUPG57
Design of an X-undulator
1379
The Advanced Photon Source Upgrade (APS-U) will deliver a new storage ring based on a Multi-Bend Achromat (MBA) lattice featuring swap-out on-axis injection, enabling the use of small diameter insertion device vacuum chambers. To leverage this advantage, we designed an X-undulator similar to the APPLE-X undulator but with a fixed gap and additional simpler magnet arrays for force compensation. The X-undulator is a pure permanent-magnet-based polarization variable undulator with a 30 mm period length and an 8.5 mm diameter bore in the beam center. The gaps between neighboring undulator magnetic arrays are 3 mm. Variation of the radiation wavelength and polarization is achieved using the longitudinal motion of the undulator magnetic arrays. This contribution covers the magnetic and mechanical design, as well as the optimization of this X-undulator.
Paper: TUPG57
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG57
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPG59
Magnetic field simulation of a planar superconducting undulator for the FEL demonstrator
1386
An Argonne-SLAC collaboration is working on the design of a superconducting undulator (SCU) demonstrator for a free-electron laser (FEL)*. A SCU magnetic structure consisting of a 1.5-m-long planar SCU magnet, and a superconducting phase shifter have been designed. A novel three-groove correction scheme has been implemented for the SCU magnet. A compact four-pole phase shifter with magnetic shields was also designed. This paper presents the calculations of the magnetic performance of the phase shifter and a planar SCU magnet, which include magnetic field and field integrals with end corrections.
Paper: TUPG59
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG59
About: Received: 14 May 2024 — Revised: 16 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPG60
Dynamic aperture in a wiggler dominated ring electron cooler of the EIC
1390
The Ring Electron Cooler (REC) is currently under design for use in the Electron Ion Collider (EIC) for hadron cooling. In this device the hadrons are cooled by the electrons and the electrons are cooled through radiation damping, which is enhanced by a number of 4 meter-long wigglers with 2.4 T field. When optimizing the beam envelope, intra beam scattering and Touschek scattering are also considered. Using a field configuration with additional focusing to keep the emittance at an acceptable value, these wigglers make up a substantial portion of the ring, with the wiggler section contributing the majority of the ring’s chromaticity. In this paper, the effects of the REC’s unusual properties on dynamic aperture are analyzed and a correction scheme is proposed.
Paper: TUPG60
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG60
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
TUPG67
Coherent radiation of a microbunched beam in a short undulator
1406
We calculate the coherent radiation of a modulated beam in a short resonantly tuned undulator taking into account the finite transverse size and the angular spread of the beam. The result allows to optimize the radiation by controlling the Twiss parameters in the undulator.
Paper: TUPG67
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG67
About: Received: 03 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
TUPG69
Tunable laser pulses enable the generation of femtosecond electron beams with controllable lengths
1409
In ultrafast electron diffraction experiments, the electron beam's length is crucial as it determines the timescale for observing ultrafast dynamic changes. Therefore, achieving continuous control over the length of these beams within a specific range is paramount for broadening the research scope in ultrafast science. This regulation ensures the accuracy of diffraction images from diverse samples, precise electron beam length measurement, and effective generation of terahertz radiation. Currently, typical methods employ radio frequency (RF) cavity compression to manage electron beam length. Nonetheless, this approach introduces time jitter and encounters challenges in continuously adjusting the electron beam length due to constraints of the RF cavity structure. This paper focuses on compressing femtosecond laser pulse methods to obtain laser pulses with continuously adjustable pulse widths. Subsequently, further controlling the distribution of photoemission electron beams can enhance the temporal resolution of ultrafast electron diffraction.
Paper: TUPG69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG69
About: Received: 14 May 2024 — Revised: 07 Jun 2024 — Accepted: 07 Jun 2024 — Issue date: 01 Jul 2024
TUPG72
An electron beam modulation laser for steady-state microbunching
1413
Steady-state microbunching (SSMB) represents an innovative scheme for generating high-power coherent radiation. This approach is expected to generate kilowatt-scale extreme ultraviolet (EUV) radiation for lithography in the semiconductor industry. During the second phase of the SSMB proof-of-principle experiment (SSMB PoP II), the creation of quasi-steady-state microbunches requires specific modulation of the electron beam. This modulation is achieved through a phase-locked laser with a high repetition rate, which enables the detection of continuous coherent radiation over multiple turns. To meet the requirements of SSMB PoP II, a high-power, high-repetition-rate, phase-stabilized pulsed laser has been developed. The single-frequency pulsed laser has been achieved using an electro-optic modulator stage, three amplification stages, and a phase-locked feedback system. Here we report on the development and test results of the electron beam modulation laser.
Paper: TUPG72
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG72
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
TUPR11
Dark current simulations in accelerating structures operating with short RF pulses
1440
The attainable acceleration gradient in normal conducting RF accelerating structure is limited by RF breakdown, a major challenge in high gradient operation. Some of the recent experiments at the Argonne Wakefield Accelerator (AWA) facility suggest the possibility of breakdown mitigation by using short RF pulses (on the order of a few nanoseconds) to drive the accelerating structures. To understand the physics of RF breakdown on a nanosecond time scale, we simulated the dark current in few accelerating structures in both long-pulse and short-pulse regimes comparatively, and studied multiple potential breakdown initiators, including field emission and multipacting. Our simulations suggest the potential of a class of accelerators designed to work in the short-pulse regime.
Paper: TUPR11
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR11
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
TUPR21
Influence of deposition parameters on the microstructure and vacuum properties of NEG-coated vacuum chamber
1460
The non-evaporable getter (NEG) coatings provide conductance-free evenly distributed pumping, low thermal outgassing rates, second electron yield, and photon-and electron-stimulated desorption. NEG coatings are crucial for achieving ultrahigh vacuum in fourth-generation diffraction storage ring vacuum systems. TiZrV thin films were deposited onto elongated CuCrZr pipes for this investigation. The influence of various deposition parameters on the microstructure and vacuum properties of NEG coatings was investigated. The microstructure, surface topography, roughness, and phase composition were evaluated using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Atomic Force Microscope (AFM), and X-ray Diffraction (XRD), respectively. Furthermore, the activation performance of the TiZrV films was investigated in relation to deposition parameters.
Paper: TUPR21
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR21
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPR26
Models for power combining magnetrons in a magic tee
1478
Industrial accelerator applications require efficient, scalable, continuous wave (CW) microwave power systems. Magnetrons are inexpensive and efficient devices for converting electrical energy into microwave power; however, their power output is limited to approximately 100 kW. Cost effective power combining magnetron systems would serve the accelerator industry by providing practical and affordable RF power to accelerator applications. In a magic tee configuration, two oscillators can be power combined and locked to a common frequency. Researchers at General Atomics, in collaboration with Thomas Jefferson National Accelerator Facility, have constructed an experiment to demonstrate the power combining of magnetrons in a such a configuration. An analytic model is presented describing the power combining efficiency of a 4-port magic tee, accounting for two magnetron output signals, an injection signal, and a reactive load. The Adler-Chen model is solved numerically using robust computational geometry techniques*. These complete solutions provide insight to the phenomena of magnetron frequency locking and optimal combining efficiency, which are compared to experiment.
Paper: TUPR26
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR26
About: Received: 17 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
TUPR27
The MESA high power 1.3 GHz CW solid state power amplifier systems
1482
The Mainz Energy recovering Superconducting Accelerator MESA is a multi-turn energy recovery linac with beam energies in the 100 MeV regime currently under construction at Institut für Kernphysik (KPH) of Johannes Gutenberg-Universität Mainz. The main accelerator consists of two superconducting Rossendorf type modules, while the injector MAMBO (MilliAMpere BOoster) relies on normal conducting technology. The high power RF system is relying completely an solid state technology. After some in-depth testing of a 15 kW prototype amplifier in 2017-2019 a modified version of the amplifier modules was developed. In 2020 series production has begun at JEMA France and first amplifiers, a 74 kW, a 56 kW and two 15 kW have been delivered to KPH lately. In this paper we will present the results of the performance measurements of the amplifiers.
Paper: TUPR27
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR27
About: Received: 13 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPR29
Novel injection locked coaxial magnetrons
1489
To meet phase stability requirements, a high peak power coaxial magnetron-based RF system with >70% efficiency would normally be injection locked to an RF source by using a circulator to send the locking signal into the magnetron through the antenna. This added requirement of a high-power circulator pushes the inherently low coaxial magnetron’s cost-per-watt to a high overall RF Power Source system cost-per- watt. For this project, the injected phase locking signal for the magnetron will use a novel input port that does not require a high- power circulator. The new input port uses the cathode stalk assembly to turn the filament-cathode into an antenna that couples to the resonant circuit of the magnetron. The coupling system between the cathode stalk, which runs at high voltage, and the RF input includes isolation for high voltage.
Paper: TUPR29
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR29
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPR32
Operation of TPS 300 kW solid-state amplifier
1492
The National Synchrotron Radiation Research Center (NSRRC) has developed a 300 kW solid-state amplifier. This 300 kW solid-state amplifier RF transmitter has been operating continuously since August 2023, consistently delivering an output of 250 kW RF power during user beam time at 500 mA. This report describes the performance of the solid-state amplifier RF transmitter during this period, module failure rates, and specific instances of malfunction.
Paper: TUPR32
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR32
About: Received: 13 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
TUPR43
Extended Jiles-Atherton hysteresis model to accurately predict fields in a Rapid Cycling Synchrotron dipole magnet
1510
Particle accelerators use high field quality magnets to steer and focus beams. Normal conducting magnets commonly use soft iron for the yoke, which is subject to hysteresis effects. It is common practice to use an initialization procedure to accomplish a defined state of the magnet for which its hysteresis behavior must be known. In this article, a variation of the scalar Jiles-Atherton model with an improved physical basis called the Extended Jiles-Atherton (EJA) model is employed to predict the B-H trajectories in a Rapid Cycling Synchrotron (RCS) magnet. Simulations are conducted using COMSOL Multiphysics using the external material feature to integrate EJA model with the Finite Element Method (FEM). Results from the experimental studies conducted on a magnet prototype are also presented. Finally, potential improvements in the model and extension to the case of a two-dimensional anisotropic material are discussed.
Paper: TUPR43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR43
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPR44
Progress on the normal conducting magnets for the Electron-Ion Collider
1514
The electron-ion collider (EIC) at Brookhaven National Laboratory (BNL) is designed to deliver a peak luminosity of 1e+34 1/cm2 1/sec. The EIC will take advantage of the existing Relativistic Heavy Ion Collider (RHIC) facility. Two additional rings will be installed: an electron storage ring (ESR) and a rapid cycling electron synchrotron ring (RCS). This paper presents an update on the normal conducting magnet designs required for both the ESR and RCS rings. The ESR will store polarized electron beams up to 18 GeV and utilizes a triplet of dipole magnets to increase the emittance at 5 GeV and generate excess bending to create additional radiation damping to allow a larger beam-beam tune shift. The RCS will accelerate single bunches of spin-polarized electrons at various energies from 5 GeV to 18 GeV, with a ramp rate of 100 ms and 1 Hz repetition rate. Both rings require dipole, quadrupole and sextupole magnets with different specifications.
Paper: TUPR44
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR44
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPR45
Test magnet for the EIC Rapid Cycling Synchrotron
1517
Brookhaven National Laboratory (BNL) was recently chosen to host the Electron Ion Collider (EIC), which will collide high energy and highly polarized hadron and electron beams with a center of mass energy up to 140 GeV and a luminosity of up to 1e+34 1/cm^2/s. Part of the accelerator complex is a Rapid Cycling Synchrotron (RCS), which is planned to accelerate electrons from 400 MeV to 18 GeV. Due to the large energy range and the given circumference of the ring, the magnetic fields of the RCS magnets at injection are very low (~mT). A test dipole magnet was constructed to study differences in field quality from 5-50 mT. The paper discusses the design of the test magnet and first measurement results.
Paper: TUPR45
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR45
About: Received: 14 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPR49
Self-correction coil for RCS dipole in Electron Ion Collider
1531
The Rapid Cyclotron Synchrotron (RCS) is an acceleration ring designed for boosting the electron energy from 400 MeV after the LINAC to 1 GeV prepared for injection into the Electron Storage Ring (ESR). Operating in a pulsed mode at 1 Hz, the RCS accelerates four consecutive bunches with dipole magnet ramping rapidly at each injection. Rapid ramping of the magnetic field induces eddy currents, causing delays and high harmonic effects which are detrimental to low-energy electron bunches. To mitigate this, cost-effective multi-turn coils with specific patterns are proposed. These coils, powered by eddy currents from main dipole field ramping, generate counter fields to cancel selected high harmonic components. This paper explores the coil pattern selection process.
Paper: TUPR49
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR49
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
TUPR50
Intra-undulator magnets for the SABINA THz FEL line: magnets design, manufacturing and measurements
1534
In the framework of the SABINA project (Source of Advanced Beam Imaging for Novel Applications), a new Free Electron Laser line will be realized at the Laboratori Nazionali di Frascati (LNF). It will be based in the SPARC_LAB laboratory with the purpose to supply radiation in the Thz/MIR range to external user. The line layout foresees two correctors between the three APPLE-X undulators devoted to providing angular and position offset correction to the beam aiming to maximize the efficiency of the FEL process. They will steer the electron beam both in the X and Y axis at the mrad level, and they will be integrated with Beam Position Monitors to perform the trajectory correction and the position monitoring at the same point. This paper presents the magnetic design of the two correctors performed by OPERA 3D software, the mechanical design, the manufacturing together with the magnetic measurement performed at the magnetic laboratory facility in LNF using a Hall probe system.
Paper: TUPR50
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR50
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
TUPR57
Stress-strain state analysis of the first-grade titanium foil of the accelerator output window in a static state
1560
The stress-strain state of the titanium foils of the accelerator output windows at various thicknesses was studied with the choice of first-grade titanium foil as a brand. The latter is more affordable and accessible compared to a second-grade titanium foil. The deformation diagram, density, Young's modulus, and Poisson's ratio of the first-grade titanium were selected as initial data. Atmospheric pressure was used as an external pressure, and the pressure from the vacuum side was taken as zero. The latter is acceptable in simulations of ultrahigh vacuum assemblies since it does not affect the overall picture of the stress-strain state. In addition to studying the central nodes of the metal foil, the sealing nodes were also considered as an object of research, with the study of stress intensity, meridional and circumferential stresses, and maximum displacements of the center. Based on the results, a function was obtained that allows us to accurately calculate the displacements of the center of the first-grade titanium foil depending on its thickness. The analysis of the received data was carried out.
Paper: TUPR57
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR57
About: Received: 03 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPR58
Analysis of laser engineered surface structures’ roughness and surface impedance
1564
This study examines Laser Engineered Surface Structures (LESS) in the context of their potential application within particle accelerators. These structures are investigated due to their efficient reduction of secondary electron yield to counteract the formation of electron clouds, a phenomenon detrimental to accelerator performance. A critical aspect of their evaluation involves understanding their radio-frequency characteristics to determine their influence on beam impedance. LESS involves intricate surface modifications, integrating etched grooves and deposited particulates, resulting in a complex surface topology. Measurements are conducted on two distinct surface patterns, from which particulates are then removed with incremental cleaning. Acquired data form the basis for mathematical models elucidating observed results. Novel approaches are investigated in addition to several established surface roughness models, including analysis of geometrical attributes of the surface topology and the associated electric currents. The aim is to develop a framework that describes roughness's influence across varying scales to assist in selecting appropriate treatment parameters.
Paper: TUPR58
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR58
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPR75
Thermal and vibrational studies of a new germanium detector for X-ray spectroscopy applications at synchrotron facilities
1589
The European LEAPS-INNOV project has launched a Research and Development program dedicated to the design of a new generation of germanium detectors for X-ray spectroscopy applications. The present article shows the results of the thermomechanical simulations of this design, based on finite element analysis (FEA) studies, under vacuum and cryogenic conditions. The first results of these simulations were published at IPAC'23*. In this new work, the final results are presented, which includes the thermal optimization of the detector with respect to the previous study, as well as new numerical simulations to investigate the effects of vibration transmission from the cryocooler to the head detector.
Paper: TUPR75
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR75
About: Received: 11 May 2024 — Revised: 16 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
TUPR77
Development of a flux-concentrator-based 2-Tesla solenoid as a round lens for ultrafast microscopy
1597
Ultrafast Microscopy using MeV beam has made significant progress in the past 5 years. However, in order to push to atomic level resolution, other than the requirements of beam source, there are also high demands in high strength focusing elements. In comparison of commercial 100s KeV level electron microscopes, an MeV imaging beamline requires Tesla level lenses, preferably round solenoid lens. Tesla class DC solenoids are prohibitively bulky and heavy, and superconducting solenoids are not cost effective. We have developed a novel miniature flux concentrator based solenoid lens system for MeV UED/UEM applications. It can reach 2-Tesla with 1e-5 level stability (depending on the pulsed current source). Here we will present detailed development process and experimental results.
Paper: TUPR77
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR77
About: Received: 06 May 2024 — Revised: 16 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPR83
PSI's open-source FPGA DSP libraries
1607
Paul Scherrer Institute (PSI) has led significant advancements in accelerator electronics development, leveraging Field Programmable Gate Arrays (FPGA) based Digital Signal Processing (DSP) across various critical systems, including Low Level RF (LLRF), Longitudinal Beam Loss Monitoring (LBLM), charge particle measurement via Integrating Current Transformers (ICT), Timing, Filling Pattern Monitor (FPM), Beam Position Monitor (BPM) and other essential beam instruments. Over the past decade, PSI’s approach to develop in-house control system platform (e.g. CPCI-S.0), has encouraged innovation. The strategic reorganization within PSI, fostering collaboration among FPGA firmware engineers, led to the inception of Open-Source FPGA DSP libraries hosted on GitHub. Serving as a comprehensive repository, these libraries empower developers by providing common FPGA IPs, fundamental DSP algorithms and Fixed-Point (FP) arithmetic units. Their presence advances prototype development by enabling rapid assembly of several measurement and or control concepts. In this contribution, we present the features and the transformative impact of the PSI Open-source FPGA libraries with a focus on LLRF. This initiative has not only empowered our team to provide valuable insights, but has also streamlined the integration of new recruits and students, enabling the seamless continuation of FPGA design frameworks.
Paper: TUPR83
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR83
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPR86
Exploring high gradient limit with cryogenic experiments at FREIA laboratory
1618
Field emission (FE) and vacuum arcs limit the maximum achievable accelerating field of both normal and superconducting cavities. The performance of accelerating cavities can be improved after a long conditioning process. Understanding this process and the formation of vacuum arcs is important for all technologies where vacuum arcs cause device failure. The understanding could be more complete with novel diagnostic tools and tests in variable environments. The cryogenic HV system in FREIA laboratory is used to study different aspects of conditioning using DC pulses at a wide range of temperatures, down to 4K. We are currently measuring FE currents during conditioning for Cu, Nb and Ti electrodes in function of temperature and breakdown rate. We are also developing a new characterization method, evaluating the surface resistivity of the electrodes during conditioning. Changes in the surface resistivity could indicate the formation of dislocations below the surface, which has been speculated to be a very important process behind conditioning. We will present the results of conditioning with the FE measurements and the surface resistivity measurements.
Paper: TUPR86
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR86
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
TUPS01
Study of longitudinal effects during transition crossing of the EIC hadron storage ring
1622
The Electron Ion Collider (EIC) Hadron Storage Ring (HSR) will accelerate all species except protons through transition to the desired storage energy. The effects at transition may cause unwanted emittance blowup beam loss due to bunch area mismatch and negative mass instability. In this paper, we will show the longitudinal dynamics of transition crossing in the HSR with current parameters using the accelerator code Beam Longitudinal Dynamics (BLonD).
Paper: TUPS01
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS01
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPS02
Impact of beam screen eddy currents on transition crossing in the EIC HSR
1626
The Electron Ion Collider (EIC) hadron storage ring (HSR) requires a beam screen made of 75 μm copper layer on top of a 1 mm thick 316LN stainless steel sheet. The eddy currents produced by the dynamic fields at the beam screens of the transition jump quadrupoles will increase the field response delay. The field response curve depends on the thickness and Residual Resistivity Ratio (RRR) value of the copper layer. Manufacturing variances of thickness and RRR in the beam screens of the gamma transition quadrupole will result in different field response delays. This paper summarizes the effects from the beam screens on transition crossing. From the varying delays, the beta-wave and eta-wave may exceed typical RHIC values. The effectiveness of the jump will be estimated using simulations of the existing RHIC lattice.
Paper: TUPS02
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS02
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPS03
An update on the transition crossing schemes for the EIC hadron storage ring
1630
The Electron Ion Collider (EIC) Hadron Storage RIng (HSR) requires the crossing of transition for all species except for protons. The current scheme for the Relativistic Heavy Ion Collider (RHIC) utilizes the gamma transition quadrupoles will be adopted for the scheme of the HSR. With rebuilt straight sections, the jump quadrupoles responsible for tune compensation will need to be placed at the proper phase advance to mitigate the beta and dispersion waves generated. As an alternative method, the beam may be nonadiabatically kicked into a stable resonance island to place the beam above transition. This paper discusses transition crossing using the matched first order method and resonance island jump schemes applied to the latest HSR lattice.
Paper: TUPS03
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS03
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPS19
Development of high-power electron gun and collector for the new antiproton decelerator electron cooler
1680
The electron cooler of the Antiproton Decelerator (AD) at CERN was initially developed for the Initial Cooling Experiment in 1979. It was subsequently adapted for use at LEAR and is currently employed in the AD. However, certain components of the cooler are now more than 40 years old and lack spare parts. To ensure the reliable operation of the AD, a new electron cooler is under development. This presentation focuses on the development of the new electron gun and collector that will provide the 2.4 A / 27 keV electron beam. The process involves choosing the gun/collector design, informed by electron-beam simulations, which aim to achieve the lowest transverse temperature of the electron beam within the cooling section and the highest collection efficiency of the collector. Subsequently, the gun and collector undergo meticulous testing and characterization on a dedicated test bench. The design undergoes iterative refinement to address issues related to high voltage sparks, vacuum pressure, and electron losses. Distinguishing features of the new cooler that make it more reliable compared to its predecessor will also be discussed.
Paper: TUPS19
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS19
About: Received: 13 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
TUPS30
Simulation study on an electron cloud and plasma waves confined in GL2000 device
1702
GL2000 Gabor-lens (GL)[1, 2] is a 2-m long device constructed and successfully operated at Goethe University. The confined electron column is much longer compared to previous constructed lenses and offers unique opportunity for investigation of electron cloud dynamics. Especially, kind of fingertip stopband structures were precisely measured in production diagram (operation function) in the year 2023 [2]. This fully reproducible behavior and dependence on a rest gas pressure left unexplained. For this purpose, a large scale multi-particles simulation PIC(particle-in-cell)-code was written in C++ and implemented on FUCHS-Cluster of the Goethe University. The main objective is to find an optimal operation parameter set for a stable operation of GLs, which is crucial for high energy hadron beam transport and focusing. Further topic will be investigation of possible longitudinal handling of bunched ion beams. The first simulation result will be presented and discussed.
Paper: TUPS30
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS30
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
TUPS48
Dielectric wakefield accelerators: THz radiation for medical applications
1770
The THz spectrum reveals distinctive vibrational and rotational modes, and when charged particle beams produce THz radiation, it becomes a promising source for generating narrowband, high-energy radiation. Particularly in dielectric wakefield accelerators, where a dielectric-lined channel is traversed by a relativistic electron beam, coherent Cerenkov radiation (CCR) is generated. The frequency and amplitude of CCR are dependent on structural geometry and drive beam parameters. Simulating a μm, pC driver beam in a dielectric wakefield structure yields longitudinal fields of MV/m, with a fundamental mode associated with a resonant peak corresponding to the process of demethylation in DNA. Achieving higher frequencies requires a thin dielectric layer or Bragg-like boundaries in the structure to constructively reinforce the fundamental frequency.
Paper: TUPS48
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS48
About: Received: 16 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPS49
Enhancing plasma wakefield accelerator analysis through machine learning
1774
In this groundbreaking study, an advanced particle-in-cell (PIC) simulation code,QuickPIC, is used to explore beam physics within Plasma Wakefield Accelerators (PWFA). The primary aim is to comprehensively analyze beam distributions, particularly those exhibiting perturbations with significant instabilities. To connect simulated beam distributions to physical observables, the study uses cutting-edge neural networks. This research underscores the transformative potential of machine learning (ML) in unraveling PWFA complexities and enhancing our capabilities in the development of advanced accelerators.
Paper: TUPS49
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS49
About: Received: 16 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPS60
Towards few-shot reinforcement learning in particle accelerator control
1804
This paper addresses the automation of particle accelerator control through reinforcement learning (RL). It highlights the potential to increase reliable performance, especially in light of new diagnostic tools and the increasingly complex variable schedules of specific accelerators. We focus on the physics simulation of the AWAKE electron line, an ideal platform for performing in-depth studies that allow a clear distinction between the problem and the performance of different algorithmic approaches for accurate analysis. The main challenges are the lack of realistic simulations and partially observable environments. We show how effective results can be achieved through meta-reinforcement learning, where an agent is trained to quickly adapt to specific real-world scenarios based on prior training in a simulated environment with variable unknowns. When suitable simulations are lacking or too costly, a model-based method using Gaussian processes is used for direct training in a few shots only. The work opens new avenues for implementing control automation in particle accelerators, significantly increasing their efficiency and adaptability.
Paper: TUPS60
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS60
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
TUPS63
Overview of machine learning based beam size control during user operation at the Advanced Light Source
1816
The Advanced Light Source (ALS) storage ring employs various feedback and feedforward systems to stabilize the circulating electron beam thus ensuring delivery of steady synchrotron radiation to the users. In particular, active correction is essential to compensate for the significant perturbations to the transverse beam size induced by user-controlled tuning of the insertion devices, which occurs continuously during normal operation. Past work at the ALS already offered a proof-of-principle demonstration that Machine Learning (ML) methods could be used successfully for this purpose. Recent work has led to the development of a more robust ML-algorithm capable of continuous retraining and its routine deployment into day-to-day machine operation. In this contribution we focus on technical aspects of gathering the training data and model analysis based on archived data from 2 years of user operation as well as on the model implementation including the interface of an EPICS Input/Output Controller (IOC) into a Phoebus Panel, enabling operator-level supervision of the Beam Size Control (BSC) tool during regular user operation.
Paper: TUPS63
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS63
About: Received: 17 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
TUPS65
Radiographic source prediction for linear induction accelerators using machine learning
1824
The penetrating radiography provided by the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility is a key capability in executing a core mission of the Los Alamos National Laboratory (LANL). Historical data from the two DARHT Linear Induction Accelerators (LIAs), built as hdf5 data structures for over a decade of operations, are being used to train machine learning models to assist in beam tuning. Adaptive machine learning (AML) techniques that incorporate physics-based models are being designed to use noninvasive diagnostic measurements to address the challenge of predicting the radiographic spot size, which depends on the time variation in accelerator performance and the density evolution of the conversion target. Pinhole collimator images recorded by a gamma ray camera (GRC) provide a direct measurement of the radiograph imaging quality but are not always available. A framework is being developed to feed results of these invasive measurements back into the accelerator models to provide virtual diagnostic measurements when these measurements are not available.
Paper: TUPS65
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS65
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPS66
Generative deep learning for 6D phase space diagnostics via physics-constrained neural networks, physics models, and adaptive feedback
1827
We present a unifying approach to generative deep learning-based 6D phase space diagnostics which combines neural networks, physics models, and adaptive feedback. Our approach includes a physics-constrained neural network (PCNN) for calculating the electromagnetic fields of intense relativistic charged particle beams via 3D convolutional neural networks. Unlike the popular physics-informed neural networks (PINNs) approach, in which soft physics constraints are added as part of the network training cost function, our PCNNs respect hard physics constraints, such as ▽·B=0, by construction. Our 3D convolutional PCNNs map entire large (256×256×256 pixel) 3D volumes of time-varying current and charge densities to their associated electromagnetic fields. We demonstrate the method on space charge dominated, relativistic (5 MeV), short (hundreds of fs), high charge (2 nC) electron beams, such as those in the injector sections of modern free electron laser and plasma wakefield accelerators. We show that the method is accurate, respects physics constraints, and that the trained 3D convolutional PCNNs perform electromagnetic calculations orders of magnitude faster than traditional solvers which require a O(N^2) process for calculating the space charge fields of intense charged particle beams. We show how we combine this with an online physics model, adaptive feedback, and automatic differentiation for real-time predictions of the 2D projections of the 6D phase space of charged particle beams.
Paper: TUPS66
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS66
About: Received: 12 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPS76
Machine learning for data analysis and control of an MeV ultrafast electron diffraction system and a photocathode laser and gun system: updates
1858
An MeV ultrafast electron diffraction (MUED) in-strument system is a unique characterization technique used to study ultrafast processes in a variety of mate-rials by a pump-probe method. Combining this tech-nology with rapid data science and artificial intelli-gence/machine learning (AI/ML) technologies in con-junction with high-performance computing can create a turnkey, automated instrument. AI-based system controls can also provide real-time electron beam optimization or provide virtual diagnostics of the beamline operational parameters. Deep learning can be applied to the MUED diffraction patterns to recover valuable information on subtle lattice variations Such a data-science-enabled MUED facility will open this technique to a wider user base with a wider variation of experience, providing an automated or semi-automated state-of-the-art instrument, with a beamline scientist orchestrating the overall data collection pro-cess. Updates on research and development efforts pri-marily in the realm of initial studies of network con-nection between the ALCF and the Accelerator Test Facility (ATF) at Brookhaven National Laboratory are presented.
Paper: TUPS76
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS76
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPS77
Applications of machine learning in ultrafast laser control
1862
In our pursuit to tailor a precise electron bunch with a photoinjector, fine-tuning laser parameters, especially those influencing the photocathode pulse, is pivotal. Our ongoing research integrates machine learning, training neural networks with experimental data from ATF. The first approach involves generating a downstream photocurrent image to replicate the emission profile, serving as a fitness function for neural network training. The second approach employs an emittance scan during each iteration of the neural network-controlled laser profile, using magnetic optics and beam profile monitors, with calculated beam emittance as an additional fitness function. Our research aims to demonstrate the potential superiority of the neural network in achieving precise laser shaping for electron beam optimization. Leveraging real data, our goal is to reduce electron beam emittance through optimized laser profiles, underscoring the impactful applications of machine learning in advancing photoinjector technology.
Paper: TUPS77
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS77
About: Received: 09 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEAD2
Orbital angular momentum beams research using a free-electron laser oscillator
1885
Orbital angular momentum (OAM) photon beams are excellent tools for non-contact optical manipulation of matter in a broad photon energy range. A free-electron laser (FEL) oscillator is well-suited for studying OAM beams with various features including a wide spectral coverage, wavelength tunability, two-color lasing, etc. Here, we report the first experimental demonstration of superposed OAM beams from an oscillator FEL. Lasing at around 458 nm, we have generated superposed OAM beams up to the fourth order as a superposition of two pure OAM modes with opposite helicities. These generated beams have a high beam quality, a high degree of circular polarization, and high power. Using external rf modulation with frequencies from 1 to 30 Hz, we also developed a pulsed mode operation of the OAM beams with a highly reproducible temporal structure. FEL operation showcased in this work can be extended to higher photon energies, e.g. using a future x-ray FEL oscillator. The operation of such an OAM FEL also paves the way for the generation of OAM gamma-ray beams via Compton scattering.
Paper: WEAD2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEAD2
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEAD3
Echo-enabled harmonic generation at FERMI FEL-1: commissioning and initial user experience
1889
The FERMI free-electron laser (FEL) facility has recently achieved a significant milestone with the successful implementation of the echo-enabled harmonic generation (EEHG) scheme in the FEL-1 amplifier line. This advancement is part of a broader upgrade strategy aiming at expanding the covered spectral range of the facility to the entire water window and beyond. Through this upgrade, the maximum photon energy of FEL-1 has been doubled and spectral quality has been enhanced. The updated FERMI FEL-1 is the first user facility operating in the spectral range 20-10 nm utilizing the EEHG scheme. It will serve also as the ideal test bench for conducting new machine studies in the perspective of future developments. In this contribution, we present the results obtained during the commissioning phase and the first user experiments.
Paper: WEAD3
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEAD3
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEAN2
Particle accelerator spin-transparent storage rings for beyond state-of-the-art science
1897
We will describe spin-transparent storage rings that exhibit spin-coherence times of several hours and store a large number of particles and their use in novel applications. For example, these rings can be used to directly measure the electric dipole moment of the electron, relevant to CP violation and matter-antimatter asymmetry in the universe, and to search for dark energy and ultra-light dark matter*. These rings can also serve as a compelling platform for quantum computing. In this presentation, we will describe how spin-transparent rings can be used in conjunction with ion traps to enhance scalability and increase quantum coherence times of ion quantum computing.
Paper: WEAN2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEAN2
About: Received: 13 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEBN1
Complete 6D tracking of a single electron in the IOTA ring
1911
We present the results of the first experiments on 6-dimensional phase-space tracking of a single electron in a storage ring, using a linear multi-anode photomultiplier tube for simultaneously measuring transverse coordinates and arrival times of synchrotron-radiation pulses. This technology makes it possible to fully reconstruct turn-by-turn positions and momentums in all three planes for a single particle. Complete experimental particle tracking enables the first direct measurements of dynamical properties, including invariants, amplitude and energy dependence of tunes with exceptional precision, and chaotic behavior.
Paper: WEBN1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEBN1
About: Received: 21 May 2024 — Revised: 23 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEBD3
Technologies and concepts for the next generation of heavy ion synchrotrons
1919
New technical approaches are under investigation to further push the intensity frontier of the next generation heavy ion synchrotrons. Residual gas dynamics and corresponding charge exchange processes are key issues which need to be overcome by means of advanced UHV system technologies, but also by a focused design of the synchrotron as a whole. Cryogenics and superconductivity enable high field operation but in synergy also enable technologies for stabilizing the dynamic vacuum. Beam loss usually implicated as driver for activation and damages is as well an important initiator for residual gas pressure dynamics. Advanced superconducting cables promise lower energy consumption, fast ramping and higher average beam intensities. The cryo-pumping properties of specially developed cryogenic inserts, can also be used to upgrade existing synchrotrons and enable operation with lower charge states and higher intensities. The advancement of laser technologies may be applied as new devices in heavy ion synchrotrons for advanced manipulations, e.g. non-liouville injection or laser cooling. With FAIR, GSI has expanded its competence for the design of novel high intensity heavy ion synchrotrons.
Paper: WEBD3
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEBD3
About: Received: 04 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEZD2
The electron cloud and its impact on LHC and future colliders
1928
The secondary emission of electrons and their interaction with the electromagnetic fields of charged particle beams can lead to the build-up of electron clouds in accelerator beam chambers. The interaction of the electrons with both the beam and the chamber walls leads to detrimental effects, such as transverse instabilities and emittance growth, beam loss, pressure rise and heat load. Such effects are systematically observed in the Large Hadron Collider (LHC) during operation with proton beams with the nominal bunch spacing of 25 ns. Furthermore, the severity of electron cloud effects has increased after each long shutdown period of the machine, due to a degradation of the beam screen surfaces with air-exposure. Consequently, electron cloud is already limiting the total intensity in the collider and is one of the main concerns for the performance of the HL-LHC upgrade. In this contribution, the present understanding of electron cloud in hadron accelerators is reviewed. Measurements and observations at the LHC are presented, the impact on performance is evaluated and mitigation measures are discussed along with lessons for future machines.
Paper: WEZD2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEZD2
About: Received: 15 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
WEPC01
Optimization of the ASU CXLS beamline in simulation via Bayesian methods
1953
Single objective Bayesian optimization is used in the simulation of the compact X-ray light source (CXLS) at Arizona State University, an inverse Compton based X-ray source, to optimize the 6D electron distribution prior to final focusing at the interaction point. For inverse Compton X-ray sources, a small 6D emittance as well as a small pulse (both transversely and longitudinally) are essential for producing bright X-ray pulses. Using IMPACT-T on a 200 pC initial charge with an RF photoinjector operating in blow-out mode, we vary parameters, such as transverse laser diameter on the cathode, RF gun phase, solenoid strength, as well as linac amplitude and phase, to balance minimizing the 6D emittance and spatial profiles. We test objective functions that are combinations of beam parameters, such as energy spread before final focus, pulse duration, and normalized emittance.
Paper: WEPC01
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC01
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPC03
Bubble-beam accelerators: breaking the paradigm
1957
Most particle accelerators utilize beams with a charge density concentrated in the center of the bunch in real 3-dimensional space and the 6-dimensional phase space. In this work, by enhancing the space-charge forces in the photo-cathode injector of the Compact Linear Electron Accelerator for Research (CLEAR) at CERN, we produce electron bunches with a “bubble-like” shape, with a charge density mostly concentrated on the outside shell. We demonstrate that the dynamics of such beams can be tailored to achieve stable uniformity in the coordinate and momentum transverse planes simultaneously. This would allow reaching a uniform dose distribution without a severe loss of particles which is of the great interest in the irradiation community. Additionally, we investigate the potential benefits of bubble-beams across several accelerator pillars: for driving light sources, for advanced acceleration technologies, and for particle colliders.
Paper: WEPC03
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC03
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPC10
Experimental testing of a ceramic enhanced accelerator cavity
1972
It is desirable to decrease the dimensions and power loss of accelerator components as much as possible when using accelerated charged particle beams on a rocket or satellite for ionospheric and magnetospheric research applications. We present the experimental results of a radiofrequency (RF) pillbox cavity loaded with a low-loss, high-permittivity ceramic placed concentrically within the cavity. We use high-electron mobility transistors (HEMTs) to power the RF at a frequency of 5.712 GHz. At this frequency, the cavity operates at a TM020 mode. The ceramic enhances the cavity's accelerating field confined within the scope of the ceramic insertion, increasing the shunt impedance, and improving the power coupling from the RF to the electron beam with the same gradient as a conventional TM010 mode cavity. Moreover, because the power coupling to the beam is improved, we were able to reduce the longitudinal dimension of the cavity compared to the conventional cavity. We show that the cavity accelerated the beam by approximately 12 keV. We also show that the cavity and ceramic can survive a flight to space by conducting vibration and shock tests that replicate the rocket launch environment.
Paper: WEPC10
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC10
About: Received: 16 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPC13
Status of the RUEDI UK national facility design
1979
RUEDI (Relativistic Ultrafast Electron Diffraction & Imaging) is a proposed facility which will deliver single-shot, time-resolved, imaging with MeV electrons, and ultrafast electron diffraction down to 10 fs timescales. RUEDI is being designed to enable the following science themes: dynamics of chemical change; materials in extreme conditions; quantum materials; energy generation, storage, and conversion; and in vivo biosciences. RUEDI is proposed to be built at STFC’s Daresbury Laboratory in the UK.
Paper: WEPC13
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC13
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC15
Simulation of a 2.6-cell normal-conducting S-band photocathode RF gun
1987
A new S-band photocathode RF gun proposed for ultrafast electron diffraction (UED) has been designed and optimized. The electron gun works at pi mode and the operating frequency is 2.998GHz. The pulsed RF power loss is 3.2MW and the final kinetic energy of the electron beam is 3.5MeV. The RF gun works at high duty factor of 0.2% and the average power loss reaches 6kW. We have used ASTRA, a space charge tracking algorithm to simulate the beam dynamics and improve the bunch properties. By comparing the simulation results under different conditions, we found that the electron beam has good properties both transversely and longitudinally under some conditions. The simulation of bunch properties helps improve spatial-temporal resolution of UED.
Paper: WEPC15
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC15
About: Received: 14 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC16
The FORTRESS Beamline at Tsinghua University
1990
High-brightness photoinjectors generate low emittance, ultrashort electron beams that are capable of tracking dynamical states of matter with atomic-scale spatio-temporal resolutions via ultrafast electron scattering, as well as providing precisely-shaped electron beams for advanced acceleration research and large-scale facilities such as free-electron laser and inverse Compton scattering. In this paper, we report on the status of the newly constructed FORTRESS (Facility Of Relativistic Time-Resolved Electron Source and Scattering) beamline at Tsinghua University, which will be dedicated for studies of advanced electron sources and photocathodes, new electron beam manipulation and characterization methods, and ultrafast electron scattering applications. The layout, beam dynamics simulation, initial beam measurement results, as well as main hardware components will be discussed in detail.
Paper: WEPC16
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC16
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPC19
Update on the MEDUSA ultrafast electron diffraction beamline at Cornell
1999
The Micro Electron Diffraction for Ultrafast Structural Analysis (MEDUSA) beamline is a 140 keV ultrafast electron diffraction (UED) beamline currently operational at Cornell. The MEDUSA beamline specializes in the study of small samples, with electron beam probe sizes down to the single micron scale. These samples can be pumped by lasers with wavelengths ranging from IR to UV. In this proceeding, we discuss the upgrades made to MEDUSA, with a focus on a pair of foil wound solenoids we built for post sample magnification of the resulting diffraction patterns, and a measurement of their aberrations. Additionally, we detail the cryogenic compatibility changes made to allow the study of samples down to liquid nitrogen temperatures.
Paper: WEPC19
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC19
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPC21
Mass production of 3.9 GHz 9-cell cavities at SHINE
2006
Two 3.9~GHz cryomodules of sixteen cavities are required in the Shanghai high-repetition-rate XFEL and extreme light facility (SHINE) linac. They are placed before the first bunch compressor to linearize energy distribution. A total of twenty-one 3.9~GHz 9-cell cavities including two prototypes were fabricated and tested. The first two prototypes reached a Q0 of 2.9x10^9 at 13.1 MV/m and a maximum accelerating gradient of 20.0 MV/m during the vertical test, with a large margin with respect to the SHINE specification. The first prototype was integrated into a small cryostat and horizontal tested. Batch fabrication of nineteen cavities started after the prototype qualification. The 3.9 GHz cryomodules are under assembling after the vertical tests. Horizontal tests are planned to start from mid of 2024. This paper will introduce the experience of the prototype development and mass production of the 3.9 GHz cavities.
Paper: WEPC21
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC21
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPC23
Overview of inverse Compton scattering feasibility studies at MESA
2014
Johannes Gutenberg University Mainz is currently constructing a new electron accelerator that employs an energy recovery scheme. The Mainz Energy Recovery Superconducting Accelerator (MESA) will provide two modes of operation: the Energy Recovery (ER) mode, which will supply an internal gas target experiment, and the Extraction Beam (EB) mode, primarily used in the P2 experiment where MESA's spin-polarized electrons will be directed towards a target. As an Energy Recovery Linac (ERL), MESA shows potential as an accelerator for an Inverse Compton Scattering (ICS)-based gamma source. To anticipate the impact of the scattering on electron beam parameters, significant for energy recovery, a novel quasi-analytical simulation code, "COMPARSE", has been developed and used for the feasibility studies. The investigations examine various applications of ICS sources at MESA. This paper gives an overview of the results as well as the limitations and possibilities of the underlying mathematical approach.
Paper: WEPC23
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC23
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPC25
Optimisation of the PERLE injector using a multi-objective genetic algorithm
2022
The PERLE (Powerful Energy Recovery Linac for Experiments) project requires an injector capable of delivering a beam current of 20 mA at a total beam energy of 7 MeV with 500 pC bunches. These requirements present challenges for achieving the high quality beam required for the main ERL loop. At low energy and high bunch charge, the electron bunches will predominantly experience emittance growth due to the space charge effects. The compensation of this emittance growth will be performed with the traditional method of two solenoids a single bunching cavity and a linac to reach the intended injection energy. Additionally, the control of longitudinal and transverse bunch size must be performed to meet the requirements at the end of the injector. For stable operation of PERLE a rms bunch length of < 3 mm is required, with transverse emittances < 6 mm·mrad and acceptable transverse size. Presented here is the re-optimization of the injector settings used during commissioning for two alternative DC photoguns. It is found that the former cathode does not perform to the standard of previous optimizations. However, a newly procured cathode when optimized can meet the requirements for PERLE.
Paper: WEPC25
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC25
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPC33
Review of MeV energy scale accelerators, their capabilities, and common applications
2036
High Energy Density Physics (HEDP) is mostly related to charged particle beams, lasers, and plasma systems. Most of the available charged particle beam systems are either of low energies (keV scale, for example, medical x-rays) or of very high energies (>GeV, for example, SLAC accelerators, CERN for fundamental research). We need MeV energy scale accelerators to study the Bragg peaks of materials and for many other reasons, such as x-ray imaging of materials, medical isotopic production, dynamic structure analysis, plasma behavior studies, plasticity tests for drinking and ocean water, and more. To generate high-energy primary e-beams, an RF accelerator or induction accelerator is first to be considered, which are well known to the accelerator and beam physics communities. But RF accelerators have the limitation of acceleration in the range of several hundred micro-ampere-level currents. The induction accelerator can transport kA-level current, but the pulse duration is compressed to a nanosecond scale. We will review the performance of known medium-energy accelerators in search of their applications, high current (mA), and long pulse (ms) capability.
Paper: WEPC33
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC33
About: Received: 09 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC39
Picometer scale emittance from plasmonic spiral photocathode for particle accelerator applications
2046
In this work we demonstrate the generation of a record low root mean square normalized transverse electron emittance of less than 40 pm-rad from a flat metal photocathode – more than an order of magnitude lower than the best emittance that has been achieved from a flat photocathode. This was achieved by using plasmonic focusing of light to a sub-diffraction regime using plasmonic Archimedean spiral structures resulting in a 50 nm root mean square electron emission spot. The emitted electrons show free electron dispersion with ∼90% of the total kinetic energy in the transverse direction. Such nanostructured electron sources exhibiting simultaneous spatio-temporal confinement to nanometer and femtosecond levels can be used for developing advanced electron sources to generate unprecedented electron beam brightness for various accelerator applications.
Paper: WEPC39
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC39
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPC40
Development of a hybrid thermionic and photoemission electron gun and dedicated test stand for ELSA
2050
A new electron gun is currently being designed for the S-band linac injector for ELSA. The objective of this development is to realize a new single-bunch injection mode in addition to the standard long pulse (multi-bunch) mode along with an improvement of the current beam parameters (e.g. emission current & transverse emittance) achieved by the existing gun. A dual mode design is being developed that utilizes a caesium dispenser cathode both as a thermionic and a photocathode using thermally assisted photoemission. In addition to the novel electron gun, a dedicated test stand is currently being designed to allow detailed characterization of both operating modes. The refined design of the gun and the current status of the test stand including beam parameter simulations are presented.
Paper: WEPC40
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC40
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPC41
High average current DC electron gun for strong hadron cooling
2053
The Strong Hadron Cooling (SHC) for electron ion collider project requires a state-of-the-art high brightness DC electron gun. The gun is required to deliver high average current (98.5 mA), 1 mm∙mrad normalized transverse emittance and 1-2.5 nC bunch charge. In this paper, we describe the high voltage design of a DC gun with an operating voltage of 550 KV, to be conditioned up to 600 KV. Unique features of this gun includes the use of inverted ceramic in this level of voltage, active cooling for the cathode and use of large/single crystal multialkali cathode grown on Silicon-Carbide substrate. A test beam line for high current test is also described.
Paper: WEPC41
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC41
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPC42
Pulsed laser deposition assisted growth of alkali-based photocathodes
2057
Alkali-based semiconductor photocathodes are widely used as electron sources and photon detectors. The prop-erties of alkali-based semiconductor materials such as crystallinity and surface roughness fundamentally de-termine the performance merits like quantum efficiency and thermal emittance. In BNL, pulsed laser deposition (PLD) was utilized to assist the growth of alkali-based photocathode materials, providing precise control of material growth and improving film quality. In the pre-sented work, films prepared with thermal and PLD sources are compared. The film quality of K2CsSb, Cs3Sb and Cs2Te grown with PLD assisted technique are reported.
Paper: WEPC42
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC42
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC43
An upgrade for the CeC cathode deposition system: co-deposition of K₂CsSb and CsTe/GaAs for CeC use
2060
Properties such as high quantum efficiency (QE), low thermal emittance, and longevity are crucial features for the rapidly developing electron accelorators. Compared to the traditional sequential deposition, the co-evaporation method is reported to yield better surface roughness, film crystallinity, and high quantum efficiency for photocath-ode materials. Here we present the effort in upgrading the coherent electron cooling (CeC) photocathode deposition system to adapt the co-evaporation growth method, the development of the co-evaporation recipe, and the prepa-ration of K-Cs-Sb photocathode using the developed system. QE of about 6.3% at wavelength 532 nm was obtained for co-deposited K2CsSb photocathode, where stoichiometry was determined by the deposition rate of each element. The system upgrade also enables the prepa-ration of GaAs photocathodes activating with Cs-Te. In our study, both CsTe and CsTe/CsO activated GaAs are prepared using the “yo-yo” method. QE of about 3.6% and 5% at wavelength 532 nm are obtained respectively. Lifetime measurements are performed and results are reported.
Paper: WEPC43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC43
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC46
Development of spin polarized electron sources based on III-V semiconductors at BNL
2064
Photocathodes capable of producing spin polarized electrons beams are required for both high energy and nuclear physics experiments. In this work, we describe in detail the commissioning of a new apparatus for photocathode characterization which includes a retarding field Mott polarimeter for the measure of photoelectron spin polarization. We will illustrate the design of superlattice structures equipped with Distributed Bragg Reflector and present the measurements of spin polarization and quantum efficiency of emitted electrons from these structures.
Paper: WEPC46
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC46
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC47
First Steps Toward Molecular beam epitaxial growth of potassium antimonide photocathodes
2068
Molecular-beam epitaxy (MBE) growth with lattice-matched substrates can lead to the synthesis of single-crystal alkali antimonide photocathodes[1]. Single-crystal photocathodes are expected to have not only high quantum efficiencies (QE) but also low mean transverse energy since they are usually grown as thin films. In this proceeding, we report the synthesis of potassium antimonide photocathodes at the PHOtocathode Epitaxy Beam Experiments (PHOEBE) laboratory at Cornell via MBE by using a sequence of shuttered growth of different unit cells. These cathodes are characterized in terms of spectral response and crystalline structure. The RHEED pattern acquired while synthesizing these photocathodes indicates epitaxial growth occurring on both SiC and Si(100) substrates. Oxidation studies were also performed to better understand the robustness of these materials under non-ideal ultra-high vacuum (UHV) conditions.
Paper: WEPC47
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC47
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPC49
Simulation of electron beams from the ELBE superconducting RF gun for ultrafast electron diffraction experiments
2072
Moving towards beam energies around 2-6 MeV in ultrafast electron diffraction (UED) experiments allows achievement of larger coherence length for better *k*-space resolution, while the temporal resolution is improved when shorter electron bunches are generated and the velocity mismatch between the optical pump and UED probe is reduced. At Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a series of superconducting cw RF (SRF) guns has been designed, build, and tested, with the latest version currently in routine operation as one of the electron sources for the ELBE Center for High Power Radiation. This SRF photoinjector produces bunches with a few-MeV energies at up to MHz repetition rates, making it a suitable electron source also for MeV-UED experiments. The high repetition rate provides a significant advantage for the characterization of samples with low scattering cross-sections such as liquids and gases. In this paper, we outline the conceptual MeV-UED instrument program under development at HZDR. We also showcase the beam quality achieved in first simulations of the ELBE SRF gun operating at low bunch charge as an electron source for diffraction experiments.
Paper: WEPC49
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC49
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPC50
GaAs cathode activation with Cs-CsO-Sb thin film
2076
GaAs cathodes are unique devices which generate a spin-polarized electron beam by the photoelectric effect when illuminated with a circularly polarized laser. Thin-film Negative Electron Affinity (NEA) surfaces have an essential role in spin polarized beam production, but they have limited lifetimes. In this study, we activate GaAs as an NEA cathode by evaporating Cs, Cs-O, and Sb metal on its cleaned surface. Here we present the latest experimental results of quantum efficiency measurements taken after evaporative deposition of multi-alkali thin-film surfaces.
Paper: WEPC50
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC50
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC51
Generation of high brightness electron beams by the 2.4-cell photocathode RF gun
2079
Modern accelerator facilities consistently require electron beams with improved characteristics such as shorter bunch lengths and higher brightness. To meet this demand, this study proposes a 2.4-cell photocathode electron gun, aiming to enhance the extraction electric field gradient on the cathode to produce high-quality beams. By effectively increasing this gradient, space charge effects in the low-energy region are suppressed, resulting in superior beam quality. Detailed design of the cavity is provided in this paper, along with a comprehensive assessment of the gun's performance through beam dynamics simulations. The simulation results demonstrate that the 2.4-cell electron gun can generate electron beams with shorter bunch lengths and lower longitudinal emittances compared to the 2.6-cell electron gun configuration.
Paper: WEPC51
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC51
About: Received: 08 May 2024 — Revised: 16 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPC54
Fabrication of semiconductor photocathodes at ACERT
2086
Photocathodes play key roles in supplying electron beams for diverse research facilities. Among them, semiconductor photocathodes stand out for their high quantum efficiency (QE). Typically, a high QE, long operation time, low thermal emittance and fast response time are desired for the accelerator community. However, the performance of semiconductor photocathodes is extremely sensitive to growth conditions. In this presentation, I will delve into recent advancements in semiconductor photocathodes fabrication at Applied Cathode Enhancement and Robustness Technologies (ACERT) of Los Alamos National Laboratory (LANL). These updates allow us to fine tune growth parameters and fabricate photocathodes with high QE and low emittance at high gradient to meet the requirements of photocathodes for Cathodes and Radiofrequency Interactions in Extremes (CARIE) project at LANL. Specifically, I will highlight our progress in developing a control system that enables to accurately control growth parameters. Furthermore, I will show our preliminary results focusing on the fabrication of CsSb and CsTe photocathodes using both sequential and co-deposition methods.
Paper: WEPC54
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC54
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPC55
A laser heated thermionic cathode
2090
There is increasing interest in developing accelerator technologies for space missions, particularly for fundamental science. In order to meet these mission needs, key accelerator technologies must be redesigned to be able to function more reliably and efficiently in a remote and harsh environment. In this work we focus on a modest electron injector system, specifically the traditional thermionic cathode. Typically such cathodes are resistively heated by a power supply that is floated at the cathode accelerating negative high voltage. This can increase engineering complexity and add a significant load to the accelerating voltage supply. We pursue laser heating a thermionic cathode in order to remove the heater power supply from the injector system, allowing for reduced engineering complexity and power requirements for the injector. To date we have shown that a simple tantalum disk cathode can be heated by a laser with similar emission performance to the same disk resistively heated.
Paper: WEPC55
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC55
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC58
Monte-Carlo photoemission model for thin film semiconductors under high fields
2097
Monte-Carlo models have been successfully used to model bulk semiconductor photocathodes, such as GaAs and others. Here we present a Monte-Carlo model under development for the photoemission from semiconductor thin films, such as Cs2Te, under high acceleration field gradient. Thin films and heterostructures, as well as high photocathode gun operating gradient and cyro-cooling, are both beneficial to high brightness electron sources. Our model employs electronic, phonon, dielectric and optical properties directly from Density Functional Theory (DFT) calculation. Furthermore, a photo excitation model based on the light interference effect in thin films is also being implemented, where our previous work indicates that such effect plays an important role in the photoemission from semiconductor thin films. Effects of the high field gradient on the semiconductor photocathode on the quality of the emitted electron beams will be discussed and used to inform a theoretical transport model based on the moment method and the cathode development for the CARIE project at LANL.
Paper: WEPC58
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC58
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC61
Concepts for more flexible UED/UEM operation
2105
Ultrafast electron diffraction and microscopy (UED/UEM) has advanced beyond proof-of-concept stage into the realm of instrumentation. To date, most UED/UEMs have been constructed around high-gradient RF-driven electron guns designed as X-FEL beam sources. A UED/UEM system driven by a CW beam, either normal- or superconducting, offers several potential performance benefits over high-gradient pulsed beam sources. These include the ability to operate at much higher average repetition rates, and the ability to extend measurement times beyond O(1 μs). If a quarterwave-type beam source is used, there is an additional possibility to vary the time between probe pulses by other than an RF period. In this paper we present the basis for this claim, discuss implications for detectors, and consider also utilization of probe electron beams at different beam energies.
Paper: WEPC61
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC61
About: Received: 08 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPC62
Development of new method of NEA Activation with Cs-Sb-O
2109
Negative Electron Affinity (NEA) activated GaAs photocathodes are the only one capable of generating spin-polarized electron beam larger than 90%. However, the NEA layer currently made from mainstream cesium (Cs) and oxygen (O) is chemically unstable, the NEA-GaAs photocathode has a rapid QE degradation over time or electron beam. As a result, it requires an operating vacuum pressure of 1e-9 Pa and has a short lifetime. Recently, a new NEA layer using heterojunctions with semiconductor thin film of alkali metals and antimony or tellurium has been proposed. The latest research shows that the NEA activation method using Cs-Sb-O is made by co-evaporation of Cs, O2 and Sb. However, the co-evaporation method has high demands on equipment. Therefore, in this work, we attempted to fabricate a Cs-Sb-O NEA layer using a separation evaporation method. Specifically, we attempted four recipes and successfully fabricated the NEA layer by Cs-Sb-O. We also evaluated the dependence of QE on Sb thickness and found that it is easy to form a NEA layer with 0.2 nm of Sb.
Paper: WEPC62
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC62
About: Received: 09 May 2024 — Revised: 23 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPC63
Dark current reduction for NSRRC photoinjector system by collimator
2112
The coherent THz facility developed at NSRRC delivers superradiant radiation with wavelengths ranging from 100 – 500 um from a gap tuneable U100 planar undulator. An S-band laser-driven photocathode rf gun has been used in its 25 MeV linac system to generate a sub-picosecond high brightness relativistic electron beam via velocity bunching for emission of coherent THz radiations. However, the high accelerating field in the gun cavity is found to be the main cause of electron field emission that generates the non-negligible background current (dark current) in the system. A portion of the field emission (FE) electrons with launching conditions close to that of the main beam can be accelerated to high energies by the booster linac structure located downstream. The primary cause of excessive radiation dosage stems from the collision of these unwanted high-energy electrons with the system's vacuum vessel. In order to limit the transportation of FE electrons from rf gun to the booster linac, a collimation system will be implemented at upstream of the booster linac. In this work, the drive linac system has been modeled with 3D space charge tracking code – IMPACT-T for both main beam as well as dark current simulation. Particle transmission and energy distribution of dark current after collimation has been simulated. Trajectories of electrons at various initial positions and particle loss mechanism have also been analyzed.
Paper: WEPC63
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC63
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPC64
Towards operating low mean transverse energy (MTE) alkali antimonide photocathodes at Argonne Cathode Test-stand (ACT)
2116
The performance and scientific reach of advanced electron accelerator applications, such as particle colliders, x-ray free electron lasers, and ultrafast electron diffraction, are determined by beam brightness. The beam brightness is constrained by the quality of photocathodes and is associated with low Mean Transverse Energy (MTE) of photoemitted electrons. To meet the requirements for applications demanding a bright electron beam, photocathodes must exhibit ultrasmooth physical and chemical roughness, a long operational lifetime, and robustness under high applied electric fields and laser fluences. In this work, we present the development of an experimental setup for the growth and in-situ characterization of high-quality, low-MTE alkali antimonide photocathodes. Additionally, we describe the modifications made to the Argonne Cathode Test-stand (ACT) at the Argonne Wakefield Accelerator (AWA) Facility, necessary for studying the performance of alkali antimonide photocathodes under real photoinjector conditions.
Paper: WEPC64
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC64
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPC65
Monte Carlo modeling of spin-polarized photoemission from GaAs with low-temperature and strained-lattice effects
2119
GaAs-based photocathodes activated to negative electron affinity (NEA) is the only existing technology that can deliver intense and highly spin-polarized electron beams for the forthcoming Electron-Ion Collider as well as enable spin-polarized scanning tunneling microscopy, ultrafast spin-polarized low-energy electron diffraction, and other cutting-edge experiments. The degree of spin-polarization of electrons photoemitted from unstrained GaAs is usually considerably less than the theoretical maximum of 50%. However, it has been experimentally observed that the degree of electron spin polarization can be increased and even exceed the theoretical maximum when the sample is cooled to low temperatures. Additionally, in strained lattice samples, the theoretical maximum of spin polarization increases to 100%. The previously developed Monte Carlo approach to spin-polarized photoemission from unstrained, room temperature NEA GaAs provides excellent agreement with experimental data in a wide range of doping densities and photoexcitation energies. This study aims to extend the model’s capabilities by incorporating both low-temperature and strained-lattice effects into the band structure and exploring their impact on spin and momentum relaxation mechanisms. Modeling of both low-temperature and strained NEA GaAs will provide a foundation for modeling photoemission from novel spin-polarized materials and complex layered structures.
Paper: WEPC65
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC65
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC66
Monte Carlo study of electron energy losses and stoichiometry effects in thin cesium antimonide photocathodes
2123
Cesium antimonide photocathodes are known for their ability to generate bright electron beams for various accelerator applications. Lab-grown polycrystalline cesium antimonides as well as Cs1Sb and Cs3Sb crystals are distinguishable; however, it remains unclear how the crystalline and other material properties of each govern the main photocathode properties such as quantum efficiency and mean transverse energy. Furthermore, photoexcited electrons undergo significant energy losses before being emitted from thin cesium antimonide films. This process is not well understood since there is very little room for scattering events within thin films. The generation of ultra-bright electron beams, capable of substantially enhancing the scientific potential of advanced accelerator applications, requires deep understanding of these and other fundamental mechanisms, which constrain photocathode performance and simultaneously determine the maximum attainable beam brightness. The purpose of this work is to use the Monte Carlo approach in a combination with Density Functional Theory to shed light on these mechanisms and provide the guidance for effective photocathode optimization.
Paper: WEPC66
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC66
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPC68
Application of a reduced phase velocity high brightness photogun for MeV ultrafast electron diffraction
2129
MeV ultrafast electron diffraction has become a new frontier for the study of molecular dynamics. With the temporal resolution of MeV-UED being limited by the electron bunch length at the target, electron sources used for this technique are becoming ever more intricate in the the push for shorter bunches length. However, moving to these complex setups makes them less feasible in a small-scale setting, such as universities, where keV-UED setups have become common place. In this paper, we use a novel travelling-wave RF photogun without any additional bunch compressor to generate ultra-short electron pulses whose lengths rival that of the most intricate magnetic or ballistic compression schemes. The broadband nature of the TW device allows for unique operation schemes that combines significant acceleration and compression all within the TW photogun. Such a device, when combined with state-of-the-art synchronization systems and lasers will be demonstrated to cross the so-called ‘50-fs time-resolution barrier’ and push towards the femtosecond regime.
Paper: WEPC68
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC68
About: Received: 03 Jun 2024 — Revised: 03 Jun 2024 — Accepted: 03 Jun 2024 — Issue date: 01 Jul 2024
WEPC69
Developments and first results from an RF test stand for high brightness C-band photoguns at PSI
2133
An international collaboration between PSI and INFN-LNF has been undertaken with the aim of developing the next generation of high brightness electron sources. Through this collaboration, two unique high gradient RF photoguns that operate in the C-band frequency regime have been designed and realized. Concurrent to this, a new high power test stand at the Paul Scherrer Institut has been commissioned to test these novel devices. Here we report on the new test stand and the first results from the high-power testing of these devices.
Paper: WEPC69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC69
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPC71
Rubidium telluride photocathodes for high quantum efficiency and low mean transverse energy accelerator applications
2137
High brightness electron sources are required to drive next generation light sources. This can only be achieved by photocathodes with high quantum efficiency (QE) and low intrinsic emittance, whilst also having long operational lifetimes and minimal dark current. Cesium telluride (Cs-Te) photocathodes are currently the favored material for many accelerators around the globe, typically chosen for its high QE and significant operational lifetime compared to other alkali-based alternatives, such as alkali antimonide and bi-alkali materials. Rubidium telluride (Rb-Te) has the potential to have a QE of a few percent with a higher work function than Cs-Te. This would lead to a lower mean transverse energy and reduced susceptibility to field emission, improving brightness and reducing dark current. In this paper, thin film Rb-Te photocathodes were grown and are characterized using X-ray photoelectron spectroscopy and QE measurements.
Paper: WEPC71
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC71
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPC73
Preparation, transport, and operation of high quantum efficiency semiconductor Cs₂-Te photocathode for SHINE
2140
According to the high repetition rate, high brightness and other operating characteristics of SHINE, the photocathode with high quantum efficiency, low emittance, and long operating lifetime is required to produce high-quality electron beam. After solving the problems of ultra-high vacuum acquisition, photocathode plug in vacuum transmission, and photocathode preparation process, the Cs-Te photocathode prepared on SHINE's photocathode preparation device based on Te intermittent and Cs continuous deposition method has a quantum efficiency greater than 10% under 265 nm light irradiation, and the quantum efficiency remains almost unchanged in the photocathode preparation device, photocathode suitcase, photocathode load lock system, and electron gun.
Paper: WEPC73
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC73
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC74
Dark current studies for a SW C-band electron gun with a deflector
2144
To generate the very high brightness beams in light sources, injectors based on radiofrequency photo-guns with very high peak electric fields on the cathode are used. However, this very high surface electric field on the surface of a radio frequency cavity leads to the generation of dark current due to the field emission effect which can damage the instrumentation and radio-activate components. Consequently, it is important to reduce the emission of these electrons and evaluate the subsequent transportation. In this paper, the deflector has been innovatively positioned at the exit of the photo-gun so as to reduce the dark current as much as possible. The dark current emission and spectrum of the dark current of the C-band electron gun have been evaluated by Particle-In-Cell simulations. The dark current before the accelerating sections has been captured and observed both with and without the deflector.
Paper: WEPC74
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC74
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPC75
Dark current in the LCLS Injector: characterization and mitigation strategies
2148
In addition to the desired electron beam, RF photoinjectors such as the one in LCLS-II produce dark current via field emission. Left unchecked, the dark current can cause various operational issues in the accelerator, such as increased radiation, damage to accelerator components and diagnostics, and desorption of gases from vacuum chamber surfaces. In this contribution, we present measurements of the dark current in the LCLS-II injector, including imaging, current, and energy distributions of the observed dark current emitters. These measurements allow us to characterize each emitter in terms of the Fowler-Nordheim model of field emission, which in turn enables us to more accurately model the behavior of the dark current in the accelerator. Taking these results into account, we also present potential active and passive mitigation strategies.
Paper: WEPC75
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC75
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPC79
The design of a 2.3-cell X-band photocathode RF electron gun
2151
Recent advancements in electron beam compression methods have enabled the production of ultrashort electron beams at the sub-femtosecond scale, significantly expanding their applications. However, the temporal resolution of these beams is primarily limited by the flight time jitter, especially during their generation in photocathode RF electron guns. In this paper, to mitigate the impact of microwave phase jitter on the flight time jitter inside the electron gun, we designed a 2.3-cell X-band electron gun, which enables the electron beams to acquire maximum output energy and minimum in-gun flight time at the same injection phase. Moreover, the tolerance of the cavity's machining errors is assessed and the RF input coupler of this cavity has been designed. Our simulation results indicate that this design provides a solid foundation for further improving the temporal resolution of the electron beam.
Paper: WEPC79
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC79
About: Received: 13 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC80
Novel high-intensity and gamma-rays sources using crystals
2155
The research is focused on finding new ways to generate high-intensity, monochromatic X and gamma-rays, surpassing the capabilities of existing methods. While Free-Electron Lasers (FEL) have limitations on photon energy, and Inverse Compton Scattering relies on powerful lasers, the search for alternatives continues. TECHNO-CLS, a PATHFINDER project funded by the European Innovation Council, is dedicated to crafting innovative gamma-ray Light Sources (LSs), utilizing linear, bent, or periodically bent crystals. Similar to magnetic undulators, crystals leverage a strong interplanar electrostatic field to prompt particle oscillation, resulting in electromagnetic radiation. By reducing the oscillation period to sub-mm dimensions, these undulators can produce tens of MeV in photon energy when exposed to GeV electron beams*. As a passive and sustainable element, CLSs show great promise. In the initial phase of the project, we identified techniques to realize CLSs, using alternated pattern deposition on silicon, using simulation to optimize the pattern and conducted experiments at CERN PS with Tungsten and Iridium crystals.
Paper: WEPC80
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC80
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPC81
Shanghai laser electron gamma source beamline in Shanghai synchrotron radiation facility
2159
Quasi-monochromatic gamma-ray beams are produced in the laser Compton slant-scattering at the Shanghai Laser Electron Gamma Source (SLEGS) of the Shanghai Synchrotron Radiation Facility(SSRF) [1,2]. The laser Compton slant-scattering was pioneered to produce X rays as early as in 1996 [3] and has more recently been used to produced gamma rays in the MeV region at UVSOR [4]. The slant-scattering makes the usage of energy-tunable gamma-ray beams compatible with that of the synchrotron radiation in synchrotron radiation facilities operated at a fixed electron beam energy worldwide. The SLEGS is designed to produce gamma rays in the energy range of 0.66 – 21.7 MeV with a flux of 1e+5 - 1e+7 photons/s [2]. We have conducted test runs of the slant-scattering in the commissioning of the beamline to confirm the designed energy tunability and flux [5]. After a more careful measurement and data processing of the γ ray energy spectra in 2023, the newest experiment results of the quality of gamma-ray beams in flux and bandwidth is obtained and will be present in this report. The gamma-ray flux is in a range of 1e+4 - 3e+5 cps in 60° - 120° and the energy-resolution is in the range of 6 - 18%.
Paper: WEPC81
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC81
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC82
Gamma beam modulation in Shanghai Laser Electron Gamma Source
2162
The Shanghai Laser Electron Gamma Source (SLEGS) is one of the beamlines of the Shanghai Synchrotron Radiation Facility, which dedicate to producing gamma beams in the slant-scattering for the first time. After produced in the interaction area, gamma rays pass through a carefully designed Gamma Modulation System (GMS), which consists of a double collimator system, attenuator system, and X/gamma imaging system. The quasi-monochromatic gamma beams with an energy spread of 4.2-4.6% are produced at the target position by using an aperture of 2 mm of the double collimator system*. The flux of gamma beams is regulated by the gamma attenuator system. X/gamma imaging system is equipped with two beam-spot monitors, an X-ray camera MiniPIX and the gamma spot monitor. MiniPIX is used for imaging electron-induced bremsstrahlung to reflect the position of gamma beam indirectly. The gamma spot monitor is used to reflect the gamma spatial distribution directly. With the GMS the gamma beam have been successfully implemented on SLEGS, the obtained high-quality gamma beam has been applied to photoneutron validation experiments. The expected results confirm the reliability of SLEGS gamma quality.
Paper: WEPC82
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC82
About: Received: 13 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC84
Comparison of WarpX and GUINEA-PIG for electron positron collisions
2166
As part of the Snowmass'21 planning exercise, the Advanced Accelerator Concepts community proposed developing multi-TeV linear colliders and considered beam-beam effects for these machines [1]. Such colliders operate under a high disruption regime with an enormous number of electron-positron pairs produced from QED effects. Thus, it requires a self-consistent treatment of the fields produced by the pairs, which is not implemented in state-of-the-art beam-beam codes such as GUINEA-PIG. WarpX is a parallel, open-source, and portable particle-in-cell code with an active developer community that models QED processes with photon and pair generation in relativistic laser-beam interactions [2]. However, its application to beam-beam collisions has yet to be fully explored. In this work, we benchmark the luminosity spectra, photon spectra, and the recently implemented pair production processes from WarpX against GUINEA-PIG in ultra-tight collisions and ILC scenarios. This is followed by a run-time comparison to demonstrate the speed-up advantage of WarpX. Ultimately, this work ensures a more robust modeling approach to electron-positron collisions, with the goal of scaling up to 15 TeV.
Paper: WEPC84
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC84
About: Received: 14 May 2024 — Revised: 16 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPG01
Beam position monitoring system and beam commissioning at APS-U storage ring
2170
Advanced Photon Source Upgrade (APS-U) storage ring, currently in installation and testing, is set for beam commissioning in early 2024. In the APS-U storage ring, there are 560 Beam Position Monitor (BPM) pickups, each equipped with high resolution electronics. This paper presents outcomes from pre-beam testing and beam commissioning of the APS-U BPM system. We discuss tailored features for advanced beam measurements, testing methodologies, challenges, and successful integration into the storage ring. Our findings demonstrate the robustness of the BPM system, emphasizing its crucial role in achieving the first beam and optimizing the APS-U storage ring's performance.
Paper: WEPG01
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG01
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPG04
Low-cost button BPM signal processing electronics for the AWA electron linac
2179
Single-pulse, high dynamic range BPM signal detection has been at the top of the Argonne Wakefield Accelerator (AWA) Test Facility's most-wanted list for many years. The AWA beamline's unique capabilities require BPM instrumentation with an unprecedented dynamic range, making it challenging to design and prototype a cost-effective solution. We have prototyped many different approaches over the years. Finally, a recent prototype shows the long-sought solution for AWA's low-cost button BPM signal detection is becoming feasible. This paper shares the design and test results of this prototype.
Paper: WEPG04
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG04
About: Received: 21 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG05
CXLS inverse Compton scattering interaction point chamber
2183
The Inverse Compton Scattering Interaction Point (ICS-IP) vacuum chamber provides a UHV environment where the electron and IR laser beams are overlapped in space and time to generate hard X-rays between 4 and 20 keV. The chamber has over two dozen motorized stages that position YAG screens with ~10 nm precision utilizing the EPICS framework for instrumentation interface. Using agile programming methods, MATLAB GUIs were created to control all the motors inside the chamber. Each YAG screen has a linear array of holes ranging between 10 microns and 2 mm that are imaged by cameras mounted on top of the chamber. Programmable focus lenses and IR mirrors are positioned to focus the IR laser at the interaction point. An X-ray optic is mounted onto a six degree of freedom nano-positioner enabling capture and collimation of X-rays coming from the IP. The X-ray optic can also be extracted from the beam path to transport the freely diverging X-rays to the experiment hutch for imaging experiments. We present the systems integration of the chamber, diagnostics elements, and control software and comment on its performance during instrument commissioning.
Paper: WEPG05
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG05
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPG07
Measurements and computer simulations of the effect of magnet vibrations on the electron beam orbit in the NSLS-II storage ring
2187
One major factor contributing to electron beam stability in a storage ring is the mechanical vibrations of magnets. At NSLS-II, we employ electromagnetic actuators to induce controlled vibrations in the support girders of the magnets. Beam position monitors distributed around the ring measure the spatial and frequency distribution of beam oscillations. The collected data is used to create and validate a computer model through a simulated commissioning tool, simulating beam motion caused by magnet vibrations. This computational model is useful for establishing mechanical stability specifications for the low-emittance upgrade of NSLS-II.
Paper: WEPG07
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG07
About: Received: 07 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPG11
Demonstration of time-resolved diagnostic in coherent electron cooling pop experiment
2203
We present a demonstration of time-resolved diagnostics within the Coherent Electron Cooling (CeC) Pop Experiment. This technique utilizes a combination of a focusing lattice, transverse deflecting cavity, and YAG screen, along with unique analytical techniques, to precisely measure and analyze the longitudinal profile information of the CeC electron beams. Additionally, our measurement of slice quantities contains slice emittance, slice current, and slice Twiss parameters. Through comprehensive analysis of these key parameters, we acquire essential information that aids in the detailed control of the beam instability of the CeC electron beams. This ultimately enhances our understanding of beam dynamics and contributes to the optimization of performance within the Coherent Electron Cooling system.
Paper: WEPG11
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG11
About: Received: 13 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG12
Measurements of the transverse beam emittance at the AREAL linac
2206
One of the main tasks for advanced experiments in modern accelerators is the generation of low-energy and high-brightness beams. The Advanced Research Electron Accelerator Laboratory (AREAL) is a linear electron accelerator based on a photocathode RF gun. The basic aim of this facility is to generate electron bunches of sub-picosecond duration with an extremely small beam emittance for ultrafast processes in advanced experimental studies in the fields of accelerator technology and dynamics, material and life sciences. In this paper, the current status and plans for further upgrades of the diagnostic system, along with the techniques used for transverse beam emittance measurements, are presented.
Paper: WEPG12
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG12
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG16
Magnetron diagnostics with a novel optical fibre-Cherenkov detector
2218
Development of an optical fiber-based beam loss monitor (OBLM) is in progress at the Cockcroft Institute (CI), UK. The novel sensor utilizes the Cherenkov radiation (CR) emitted in optical fibers by relativistic particle showers generated in beam loss or breakdown events. Breakdowns are a problem for high-power magnetrons, such as those in medical accelerator facilities, as damage to the magnetron cathode reduces the device efficiency and lifetime. These events can be detected by emitted CR channeled along the fibers to photomultiplier detectors, and a time-of-flight method can be used to calculate the breakdown location from the CR arrival time. This has previously been demonstrated with the OBLM system on RF cavities (at CLARA, Daresbury Laboratory, and CTF3, CERN); and allows for rapid and reliable breakdown detection which is important for damage mitigation. This contribution presents proof-of-concept measurements from OBLM studies into magnetrons at Teledyne e2v, Chelmsford. It also discusses design adjustments made to improve the detector sensitivity and how the performance can be enhanced using the sensor (or similar).
Paper: WEPG16
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG16
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG18
Gas jet-based beam profile monitor for the electron beam test stand at CERN
2225
A non-invasive bidirectional beam profile monitor using beam-induced fluorescence upon a thin sheet of gas has been developed at the Cockcroft Institute in collaboration with CERN and GSI. This device is particularly suited to the Electron Beam Test Stand, and as such, a bespoke gas injection has been optimized for this specific use-case to provide diagnostics unavailable to conventional scintillator screens. The bidirectionality allows for the observation of beam reflections back along the beam path as a result of a beam dump with non-optimized repeller electrode potential. Furthermore, the heating effects of a high current DC beam are negated by the self-replenishing gas sheet. These benefits make this device ideal for use in the Electron Beam Test Stand. This contribution summarizes the optimization study of the gas jet generation performed with a multi-objective genetic algorithm to meet required screen dimensions whilst maintaining acceptable vacuum levels.
Paper: WEPG18
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG18
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPG19
Experimental study into the invasiveness of a gas jet beam profile monitor for charged particle beams
2229
A minimally-invasive gas jet in-vivo dosimeter for medical treatment facilities is being developed at the Cockcroft Institute (UK), to provide full online (real time) monitoring with less frequent calibration. The monitor functions via a thin, low-density, gas jet curtain, intersecting with the beam. Online monitoring is crucial for hadron beams where acceptable dose tolerances are narrow, hence the beam should be perturbed only by the minimum amount necessary to acquire a signal. An experiment to determine the level of invasiveness of supersonic gas jet beam profile monitors was undertaken to quantify how much the gas jet perturbs the beam. This was accomplished using a 10 keV electron gun with a maximum current of ~100 μA, available in the DITAlab of the Cockcroft Institute. A scintillator screen and Faraday cup were placed in path of the beam to measure the change in beam size and current respectively. In the future, a simulation study using GEANT4 will be completed with the experimental beam parameters to verify the results. This contribution examines the perturbation experienced by a particle beam from a gas jet beam profile monitor, and quantifies the effect the jet has on the beam size and current.
Paper: WEPG19
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG19
About: Received: 14 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPG20
An improved beam-based method to calibrate the relative gains of the beam position monitor pick-up electrodes at the Cornell Electron Storage Ring
2232
The Cornell Electron Storage Ring (CESR) beam position monitors (BPM) consists of four button-shaped pick-up electrodes, each individually instrumented with readout electronics that allow acquisition of turn-by-turn data. The beam position is reconstructed using the measured signal amplitude from the four electrodes. Systematic effects such as physical differences between the electrodes (displacement, tilt) and gain differences between the readout electronics bias the measured amplitudes, thus the measured beam position. An improved beam-based method to measure the relative gains has been developed and validated using Monte Carlo simulations, and has been successfully deployed at CESR. It relies on solving a system of equations for different beam positions and simultaneously for the relative gains, knowing the response map of the pick-up electrodes as a function of beam position. The typical implementation uses 9 beam positions at one BPM with horizontal and vertical spatial separation greater than 500 microns. The main limitation of the method is time; it takes about 15 minutes to collect data for a single/few BPMs, making it impractical to calibrate all the 100 BPMs. We are planning on using a transverse resonance island buckets (TRIBs) lattice demonstrated at CESR to allow collecting 9 beam positions at all BPMs at once in a matter of minutes. This paper will present the new method, how it performs and its deployment at CESR.
Paper: WEPG20
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG20
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPG22
Slice energy spread measurements of a 20 MeV electron beam at PITZ
2240
Due to improvements of the performance of FELs, the measurements of the beam’s slice energy spread is becoming increasingly important for optimization of the brightness. Of particular interest are measurements of the uncorrelated energy spread near the gun as this determines the lower limit of the energy spread for the rest of the machine. At the Photo Injector Test facility at DESY in Zeuthen (PITZ), the uncorrelated energy spread is measured of an electron beam generated from an L-band electron gun and accelerated to 20 MeV with a booster cavity. The energy spread of the central time slice is measured using a transverse deflecting structure (TDS) and a dispersive arm to image the longitudinal phase space. Scans of the TDS voltage and quadrupole strengths are used to remove the contributions from the TDS, transverse emittance, and imaging resolution. Presented is an overview of the measurement procedure, resolution, and results of measurements tests.
Paper: WEPG22
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG22
About: Received: 16 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG38
Geant4 simulations on Faraday cup design for PIP-II Laser wire scanner system
2295
The Proton Improvement Plan-II (PIP-II) accelerator upgrade at Fermilab represents a groundbreaking leap forward in high-energy physics research. This ambitious initiative involves enhancing Fermilab's accelerator complex by replacing the current linear accelerator with a warm front end (WFE) capable of accelerating H- beams up to 2.1 MeV. Subsequently, a superconducting linac further accelerates these beams up to 800 MeV. To pre-cisely measure the transverse beam profile, a combination of traditional wire scanners at the WFE section and Laser wire scanners along the superconducting linac are planned for implementation. This investigation centers on refining the Faraday cup design for the PIP-II Laser wire scanners by utilizing GEANT4, a Monte Carlo simulation toolkit. Leveraging this method enables a comprehensive analysis of particle trajectories, energy deposition, secondary electron emission, backscattering, etc., facilitating optimization through adjustments to cup geometries, materials, and placement to maximize its efficacy in beam diagnostics.
Paper: WEPG38
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG38
About: Received: 17 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPG39
Ionization profile monitors for the IOTA proton beam
2299
We present the design details and outline the construction progress of the Ionization Profile Monitors (IPMs). Two IPMs, designed for transverse beam size measurements of 70 MeV/c protons, are slated for installation—one horizontal and one vertical—in the IOTA ring. These IPMs are fast (1.8 microsecond, one turn), accurate (to better than 10%) and non-destructive diagnostics. They will play a pivotal role in facilitating comprehensive beam studies, particularly in investigating the dynamics of space-charge dominated proton beams in IOTA.
Paper: WEPG39
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG39
About: Received: 11 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG40
Wire scanner assessment of transverse beam size in the Fermilab side-coupled linac
2303
The Fermilab Side-Coupled Linac contains seven 805 MHz modules accelerating H- beam from 116 MeV to 400 MeV. Each module contains at least one wire scanner, yielding beam intensity at positions along a transverse direction. These wire scanners each contain three wires, mounted at different angles: "X", "Y", and 45° between "X" and "Y" to analyze coupling. Recently, a significant amount of transverse X-Y coupling was identified within wire scanner data from the Side-Coupled Linac, which has been present in data from the past decade. This realization has prompted an investigation into the wire scanner's utility as a diagnostic tool in the Fermilab Linac. This work presents efforts to better characterize the wire scanners' limitations and the phenomenon occurring in the Side-Coupled Linac.
Paper: WEPG40
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG40
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPG42
Final design of the Cryogenic Current Comparator for FAIR
2311
Cryogenic Current Comparators (CCC) are ultrasensitive DC-Beam Transformers based on superconducting SQUID technology. With the aim to provide a robust and high resolution intensity measurement for application at FAIR and CERN machines, numerous steps of optimization were carried out over the last years by a collaboration of institutes specialized on the various subtopics. Different types of CCCs with respect to pickup, magnetic shielding, SQUID types and SQUID coupling have been developed and were tested in the laboratory as well as under beamline conditions. In parallel, the cryogenic system has steadily been optimized, to fulfill the requirement of a standalone liquid helium cryostat, which is nonmagnetic, fit for UHV application, vibration damped, compact and accessible for maintenance and repair. We will present the particular development steps and describe the final version of the CCC for FAIR as their outcome. The latest beamtime results are shown as well as recent tests with the cryogenic system. The CCC for FAIR will be a so called Dual-Core CCC (DCCC), which runs two pickups in parallel with independent electronics for better noise reduction and redundancy. The magnetic shielding will have an axial meander geometry, which provides superior attenuation of external magnetic noise.
Paper: WEPG42
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG42
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG43
Design of a 3-cell rectangular deflecting cavity for a compact THz-FEL
2315
Bunch length is an important parameter for free-electron laser (FEL). The deflecting RF cavity was used in the beam length diagnostic instrument. In this paper, we present the design of a 3-cell rectangular deflecting RF cavity for a compact terahertz (THz) free-electron laser (FEL) facility. The 3-cell deflecting cavity has a residual orbit offset of zero as compared to single-cell deflecting cavity. Rectangular deflecting cavity does not need to lock the dipole polarisation direction as compared to cylindrical cavity. The time resolution of the measurement system can reach 500 fs. In this paper, the cavity design is carried out using CST and the results of cavity analysis are presented. Particle tracking is performed with the Astra code and the space charge effect is taken into account.
Paper: WEPG43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG43
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG44
Using CT algorithm to reconstruct electron beams transverse phase space in HUST-UED
2319
Accurate beam emittance and transverse phase space measurement are crucial for obtaining high-quality sample information in Ultrafast Electron Diffraction (UED). Traditional methods rely on general initial assumptions about the electron beam's phase space and lack specific distributions. The transverse phase space reconstruction technique based on the Computed Tomography (CT) algorithm eliminates the need for prior assumptions, resulting in more precise measurements. In this paper, we utilize an Algebraic Reconstruction Technique (ART) algorithm for HUST-UED, enabling the reconstruction of the beam transverse phase space distribution at the sample location and further facilitating system optimization.
Paper: WEPG44
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG44
About: Received: 06 May 2024 — Revised: 16 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPG49
Beam studies using a Cherenkov diffraction based beam position monitor for AWAKE
2327
A beam position monitor based on Cherenkov diffraction radiation (ChDR) is being investigated as a way to disentangle the signals generated by the electromagnetic fields of a short-pulse electron bunch from a long proton bunch co-propagating in the AWAKE plasma acceleration experiment at CERN. These ChDR BPMs have undergone renewed testing under a variety of beam conditions with proton and electron bunches in the AWAKE common beamline, at 3 different frequency ranges between 20-110 GHz to quantify the effectiveness of discriminating the electron beam position with and without proton bunches present. These results indicate an increased sensitivity to the electron beam position in the highest frequency bands. Furthermore, high frequency studies investigating the proton bunch spectrum show that a much higher frequency regime is needed to exclude the proton signal than previously expected.
Paper: WEPG49
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG49
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG52
Commissioning and experiments with a compact transverse deflecting system at FLUTE
2339
A Compact Transverse Deflecting System (Compact-TDS) designed for longitudinal electron bunch diagnostics in the femtosecond regime is presently undergoing commissioning at the Karlsruhe Institute of Technology (KIT). This technique, based on THz streaking using a resonator structure, demands a high level of electron beam controllability and stability at the micrometer scale. To meet these requirements, the linear accelerator FLUTE (Ferninfrarot Linac- Und Test-Experiment) has undergone major upgrades in 2023, incorporating a new RF system equipped with a klystron, RF photoinjector and solenoid magnet. In this contribution, we present first experiments conducted with the Compact-TDS at FLUTE, utilizing the upgraded RF setup.
Paper: WEPG52
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG52
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG53
Resonator design optimization for a compact transverse-deflecting system
2343
Various design options have been studied and simulated using CST MICROWAVE STUDIO for a compact transverse-deflecting system proposed for diagnostics of extremely short electron bunches. The idea of the method is to use terahertz radiation, produced from optical rectification of the facility’s electron gun laser pulse. The proposed system is to be checked experimentally at the test facility FLUTE (Ferninfrarot Linac- und Test-Experiment) at Karlsruhe Institute of Technology (KIT). The present paper is focused on the simulations of the resonator providing interaction between the electron bunch and the terahertz pulse. Two types of resonators and their arrays have been studied for this purpose: inverse split-ring resonator and tilted slit resonator. Different types of terahertz pulse structure have been studied, including plane wave and transversely focused (Gaussian) beam. Useful analytical models have been proposed to systematize the results of the simulations.
Paper: WEPG53
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG53
About: Received: 13 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG55
Longitudinal phase space density tomography constrained by the Vlasov-Fokker-Planck equation
2350
Understanding the evolution of complex systems with numerous interacting particles requires advanced analytical tools capable of capturing the intricate dynamics of the phase space. This study introduces a novel approach to longitudinal phase space density tomography in an electron storage ring, leveraging constraints imposed by the Vlasov-Fokker-Planck equation. The Vlasov-Fokker-Planck equation provides a comprehensive description of the evolution of density functions in phase space, accounting for both deterministic and stochastic processes. Measurements of the turn-by-turn bunch profile offer a time-dependent projection of the phase space. Observing the bunch profile evolution of charged particles in regimes characterized by a rich phase space dynamics presents a challenging inverse problem for reconstructing the phase space densities. In this work, we present a tomographic framework for reconstructing the longitudinal phase space density of an electron bunch at the Karlsruhe Research Accelerator (KARA). This framework utilizes simulated data and applies the Vlasov-Fokker-Planck equation to drive the reconstruction process.
Paper: WEPG55
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG55
About: Received: 13 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPG56
Simulations of an electro-optical in-vacuum bunch profile monitor and measurements at KARA for use in the FCC-ee
2354
The Karlsruhe Research Accelerator (KARA) is an electron storage ring for accelerator research and the synchrotron of the KIT light source at the Karlsruhe Institute of Technology (KIT). KARA features an electro-optical (EO) in-vacuum bunch profile monitor to measure the longitudinal bunch profile in single shot on a turn-by-turn basis using electro-optical spectral decoding (EOSD). A simulation procedure has been set up to evaluate its suitability as a beam instrumentation for the operation of the future electron-position collider FCC-ee. In order to assess the simulations, this contribution focuses on a comparison to EO sampling (EOS) measurements at KARA and a study on the heat load of the EO crystal due to the expected high bunch repetition rate envisioned for FCC-ee.
Paper: WEPG56
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG56
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPG63
Optimizing current density measurements for intense low beta electron beams
2368
The cathode test stand at LANL is utilized to test velvet emitters over pulse durations of up to 2.5 µs. Diode voltages range from 120 kV to 275 kV and extracted currents exceed 25 A and depend on cathode size and pulse duration. Current density measurements taken with scintillators or Cherenkov emitters produce inconsistent patterns that disagree with the anticipated beam profile. Several factors contribute to the measured beam distribution, such as electron scatter, X-ray scatter, and Snell’s law. Here, we present a range of experiments designed to evaluate both electron scatter and Cherenkov emission limits in efforts to optimize current density measurements. For electron ranging studies, metal foils of different densities and thicknesses are coupled with a scintillator, which is then imaged with an ICCD. Similarly, Cherenkov emission and Snell’s law are investigated through imaging materials with differing indices of refraction over a range of beam energies. MCNP6® modeling is utilized to further guide and evaluate these experimental measurements.
Paper: WEPG63
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG63
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPG66
Effects of delta ray electrons on measurement uncertainties of harp system
2378
A harp system, which is a multi-wire beam profile monitoring (MWPM) system, is planned upstream of the spallation target to make in situ calibration of beam current density configuration on the target along with beam imaging from luminescent coating on the beam entrance window at the Second Target Station (STS) of the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). This beam interception-based beam diagnostics system on the target will be used to ensure that the maximum beam loads on the target are within the design range during neutron production. Current design of the harp consists of three layers of measurement wires each of which is sandwiched between voltage biasing wire planes. The signal obtained from each measurement wire layer is disturbed by secondary electrons (SE) and delta rays produced by beam-matter interactions in neighboring wires and ionization of residual gases in accelerator vacuum. While the backgrounds from SE can be suppressed by voltage biasing, the delta-ray electrons with kinetic energies above keV ranges overcome the electric potential bias. In this paper, we study the effects of delta-rays on the measurement uncertainties of MWPM using the particle transport simulation code FLUKA. Furthermore, the cases where the harp system is installed in the proximity of a large delta ray sources such as proton beam window or in the core vessel filled with sub-atmospheric gas have been studied.
Paper: WEPG66
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG66
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPG67
SiPM integration testing for FACET-II pair spectrometer
2382
A pair spectrometer, designed to capture single-shot gamma spectra over a range extending from 10 MeV through 10 GeV, is being developed at UCLA for installation at SLAC’s FACET-II facility. Gammas are converted to electrons and positions via pair production in a beryllium target and are then subsequently magnetically analyzed. These charged particles are then recorded in an array of quartz Cherenkov cells attached to silicon photomultipliers (SiPMs). As the background environment is challenging, both in terms of ionizing radiation and electromagnetic pulse radiation, extensive beamline testing is warranted. To this end, we present Geant4 Monte Carlo studies, assembly of the SiPMs, and future testing plans.
Paper: WEPG67
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG67
About: Received: 16 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPG68
Sub-femtosecond resolution electro-optical arrival-time measurement of relativistic electron bunches in a free-electron laser
2386
SwissFEL is a normal conducting linear accelerator driving two separate free-electron laser (FEL) lines – one for soft and one for hard x-rays. We report jitter and correlation measurements of two electro-optical Bunch Arrival-Time Monitors (BAMs), which use directly the pulses from a mode-locked laser oscillator. The arrival-time is encoded in the amplitude of one single reference laser pulse in a fiber coupled Mach-Zehnder modulator driven by a fast RF-transient from a button pick-up. Using the modulation slope and the laser amplitude jitter, we demonstrate <1 femtosecond resolution at 200 pC bunch charges for the BAM with a 16 mm pick-up beam pipe diameter and <10 fs at 10 pC for the BAM with 8 mm pick-up beam pipe diameter. We also report a jitter correlation measurement of two independent BAMs over 1 min at 100 Hz machine repetition rate as well as a similar correlation measurement of one single BAM station with 8 mm pick-up beam pipe diameter and having two identical high resolution channels. The measured correlations are as low as 1.3 fs rms resulting in sub-femtosecond resolution of the optical detection scheme.
Paper: WEPG68
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG68
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPG70
Beam diagnostics status for the Korea 4GSR project
2389
The Korean 4GSR project is currently under construction in Ochang, South Korea, with the aim of first beam commissioning in 2027. Designed to achieve an emittance approximately 100 times smaller than that of third-generation synchrotron radiation storage rings, the project requires the development of several high-precision beam diagnostic devices. In particular, the beam position monitor is designed to reduce longitudinal wake impedance, thereby suppressing heating and beam instability. The electronics component has also been developed using RFSOC to enable Turn by Turn data acquisition and Bunch by Bunch beam position monitoring. Additionally, a Beam Loss Monitor utilizing 100 Hz operating-rate scintillating optical fibers has been developed, and an enhanced beam profile monitor utilizing GAGG has also been created. Furthermore, the development progress of a multi-bunch energy measurement beam position monitor system for linear accelerator energy feedback will be introduced. This presentation aims to provide an overview of the current status of beam diagnostic devices developed for the 4GSR project, including details on the overall system configuration.
Paper: WEPG70
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG70
About: Received: 21 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG72
Fast laser focal position correction using deployed models
2393
Ultrafast high repetition-rate laser systems are essential to modern scientific and industrial applications. Variations in critical figures of merit, such as focal position, can significantly impact efficacy for applications involving laser plasma interactions, such as electron beam acceleration and radiation generation. We present a diagnostic and correction scheme for controlling and determining laser focal position by utilizing fast wavefront sensor measurements from multiple positions to train a focal position predictor. We present the deployment and testing of this scheme at the BELLA Center at Lawrence Berkeley National Laboratory. Online optical adjustments are made to a telescopic lens to provide the desired correction on millisecond timescales. A framework for generating a low-level hardware description of ML-based correction algorithms on FPGA hardware is coupled directly to the beamline using the AMD Xilinx Vitis AI toolchain in conjunction with deployment scripts.
Paper: WEPG72
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG72
About: Received: 16 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPG76
Developments of beam loss monitors for FETS-FFA test ring
2396
ISIS-II is the UK's proposed next-generation pulsed, spallation neutron source, and is expected to be driven by a MW-class proton accelerator. A Fixed Field Alternating gradient (FFA) machine is one accelerator configuration being considered. A demonstrator machine, called FETS-FFA, is now being actively developed. Beam Loss Monitors (BLMs) for this demonstrator are presented with the unique challenge of low-energy (3-12 MeV) and low intensity (1e+11 ppp) beams, and should provide turn-by-turn measurements during commissioning as well as form a vital component of the Machine Protection System (MPS). The final BLM systems will operate in stray magnetic fields from the main magnets, and need to fit in the limited available space. This paper presents a feasibility study of using a combination of Ionisation Chambers (IC) and Scintillation Detectors (SD). The ideal geometry of both BLM types will be discussed, and comparisons made between Monte Carlo simulations and beam tests on the FETS linac at the Rutherford Appleton Laboratory.
Paper: WEPG76
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG76
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPG77
Charge measurement systems on CLARA at Daresbury laboratory
2400
CLARA is a 250 MeV electron facility at Daresbury Laboratory, which will provide short bunches between 1 and 250 pC for a variety of experiments, including novel acceleration experiments. As part of the Phase 2 upgrade new charge measurement systems have been installed. This paper presents the charge measurement systems that will be used on CLARA, as well as commissioning results without beam for some of those systems. CLARA will include a Wall Current Monitor (WCM), 3 Integrating Current Transformers (ICTs) and five Faraday cups. The ICTs are commercial systems by Bergoz, while a custom front-end has been designed for the WCM and Faraday cups, which includes calibration circuitry and switchable gain. Calibration results, including measurements of resolution, are presented for the in-house front-end design.
Paper: WEPG77
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG77
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPG78
A single shot THz spectrometer for the FEBE experimental facility
2403
After current upgrades are completed, the Compact Linear Accelerator for Research Applications (CLARA) at Daresbury Laboratory (UK) will be capable of producing femtosecond-scale electron bunches, which will be used in the full energy beam exploitation (FEBE) experimental area. CLARA will employ multiple techniques to manipulate the longitudinal beam profile, including a variable bunch compressor (VBC). Optimisation procedures for the CLARA modules must be devised, which will require longitudinal diagnostics. Previous longitudinal diagnostics used on CLARA were multi-shot, but for user experiments a single-shot diagnostic operating at the machine repetition rate of 100 Hz is needed. Here, we present a single-shot, four-channel spectrometer to measure THz coherent transition radiation (CTR) produced by electron bunches, which will be used to deduce information about the bunch profile. In the device, a set of frequency-selective elements designed at STFC RAL Space (UK) distribute specific bandwidths onto single-shot pyroelectric detectors based on earlier wideband THz diagnostics on CLARA. The frequency-selective elements have been characterised using both simulations and THz time-domain spectroscopy. A start-to-end computer model of the spectrometer was created, and simulations were performed showing that the spectrometer can be used for both sextupole tuning on the FEBE arc and optimisation of the compression of the CLARA VBC. The instrument is currently being assembled and tested, and commissioning with beam is planned for the summer of 2024.
Paper: WEPG78
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG78
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG82
Real-time measurements of the RF-path of an electro-optical bunch arrival-time monitor with integrated planar pickup structure with low-charge electron beams at ELBE
2407
Ultra-low-charge operation of free-electron lasers down to 1 pC or even lower, requires adequate diagnostics for both, the users and the operators. For the electro-optical bunch-arrival time monitor (BAM) a fundamental design update is necessary to yield single-digit fs precision with such low charges. In 2023 a vacuum sealed demonstrator for a novel pickup structure with integrated combination network on a printed circuit board (PCB) was built for operation at the free-electron laser ELBE at HZDR. Together with a new low-pi-voltage ultra-wideband traveling wave electro-optical modulator, this concept reaches an estimated theoretical jitter charge product of 9 fs pC. Proof-of-concept measurements with the pickup demonstrator were carried out at ELBE.
Paper: WEPG82
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG82
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG83
Development of an active beam-stabilization system for electrofission experiments at the S-DALINAC
2411
The r-process fission cycle terminates the synthesis of heavy elements in binary neutron-star mergers. Fission processes of transuranium nuclides will be studied in electrofission reactions at the thrice-recirculating electron accelerator S-DALINAC*. Due to the minuscule fissile target, the experimental setup requires an active beam-stabilization system with high accuracy and a beam position resolution in the sub-millimeter range. Requirements and concepts for this system regarding beam diagnostics elements, feedback control and readout electronics will be presented. The usage of a cavity beam position monitor and optical transition radiation screens to monitor the required beam parameters will be discussed in detail. Additionally, various measurements including a study of beam stability performed in the injector section of the S-DALINAC to assess requirements and limits for the beam-stabilization system will be presented. Finally, the application of advanced machine learning methods, such as neural networks and agent-based reinforcement learning, will be discussed.
Paper: WEPG83
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG83
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPG84
Status of the new bunch length measurement system downstream of the injector of the S-DALINAC
2415
Energy-recovery linacs provide high beam currents with lower RF power requirements compared to conventional machines while maintaining the high beam quality of a linac. The S-DALINAC is a thrice-recirculating accelerator operating at a frequency of 3 GHz that is capable of being operated as a multi-turn superconducting energy-recovery linac. Its efficiency is currently limited by the bunch length, which by now is measured using the RF zero-crossing method. In order to improve both accuracy and measurement time a new setup using a streak camera is developed. Optical transition radiation from electron bunches passing an aluminum-coated Kapton screen is used to produce light pulses that can be measured with the streak camera. An imaging system consisting of multiple mirrors is used to maintain a high temporal resolution for the measurement and to support in shielding the streak camera from harmful radiation. The device will be used at two different measurement setups downstream of the injector. The design and current status of the measurement setup will be presented.
Paper: WEPG84
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG84
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPG86
Gas jet dosimeter measurements at DCF for medical accelerator applications
2418
Achieving non-invasive in-vivo dosimetry is a critical objective in the field of ion beam therapy. The comprehensive real-time characterization of the ion beam is highly desirable to ensure the safety of patients, treatment precision, and the efficiency of the treatment facility. However, current methods have limitations in terms of the information they provide and can be invasive to the beam. This contribution focuses on the development of a non-invasive, gas jet-based in-vivo dosimeter for use in treatment facilities. This technique relies on a non-disruptive interaction of a low-density supersonic gas jet curtain with the primary treatment beam. An existing gas jet monitor-based ionization profile monitor was modified and coupled with the accelerator beamline at the Dalton Cumbrian Facility (DCF), UK (United Kingdom). The aim of the test was to conduct proof-of-concept measurements for the profile and dosimetry of beams having characteristics similar to the medical treatment facilities. Measurements were carried out for proton and carbon beams of varied sizes, energies, and currents. The results obtained from these measurements demonstrated the feasibility of such a dosimeter and are instrumental for its improvement. This contribution introduces the design of the adapted gas jet dosimeter, discusses the findings from the measurements, highlights the dosimetry challenges addressed and outlines the scope of improvement for an online non-invasive gas jet in-vivo dosimeter.
Paper: WEPG86
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG86
About: Received: 09 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPG88
Design of a constant-gradient backward-traveling-wave accelerating structure for irradiation
2426
To develop a high-power, high-efficiency electron irradiation accelerator system with an adjustable electron beam, a novel constant-gradient backward-travelling-wave (BTW) accelerating structure has been designed. This accelerator tube implements a backward-travelling-wave design, which offers the advantages of short filling time and low power reflection, which are characteristic of traveling-wave acceleration structures, and can incorporate a nosecone design to achieve high shunt impedance. The constant-gradient concept is adopted to further enhance the electron beam power and beam efficiency. This paper presents the design of the BTW accelerating structure, encompassing parameter estimation and comprehensive three-dimensional simulations to validate the concept.
Paper: WEPG88
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG88
About: Received: 14 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG90
Reflectivity studies and production of new flat mirrors for the Cherenkov threshold detectors at CERN
2434
Cherenkov threshold detectors (XCET) are used for identifying particles in the experimental areas at CERN. These detectors observe Cherenkov light emitted by charged particles travelling inside a pressurized gas vessel. A key component of the XCET detector is the 45-degree flat mirror reflecting the Cherenkov light towards the photomultiplier (PMT). A thorough analysis and optimization was conducted on the design and materials of this mirror, along with the surface coatings and coating techniques. A suitable manufacturing process was selected, and the first mirror prototype was produced, installed, and tested in the East Area at CERN. Experimental data obtained during beam tests is presented to assess the efficiency of the new coating and materials used.
Paper: WEPG90
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG90
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPR08
Electron cloud studies for DAΦNE collider and FCCee damping ring
2469
DAΦNE is a a medium energy electron-positron collider operating in the National Laboratory of INFN at Frascati, Italy. The accelerator complex consists of two rings with an approximate circumference of 97 m. High-intensity electron and positron beams circulate and collide with the center of mass energy of around 1.02 GeV. The FCCee is an ongoing lepton collider project and its current injector design includes a damping ring for emittance cooling of positron beams. The electron cloud is one the most important collective effects and can represent a bottleneck for the performances of accelerators storing particles with positive charge. Several undesired effects such as transverse instabilities, beam losses, emittance growth, energy deposition, vacuum degradation may arise due to interaction of the circulating beam with the e-cloud. The aim of this presentation is to provide e-cloud buildup simulations for the DAΦNE positron ring and the Damping Ring of FCCee. This study will also include experimental studies concerning the instabilities induced by the e-cloud exploiting the opportunity offered by the positron beam at DAΦNE.
Paper: WEPR08
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR08
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPR14
Selected advances in the accelerator design of the Future Circular Electron-Positron Collider (FCC-ee)
2493
In autumn 2023, the FCC Feasibility Study underwent a crucial “mid-term review”. We describe some accelerator performance risks for the proposed future circular electron- positron collider, FCC-ee, identified for, and during, the mid-term review. For the collider rings, these are the collective effects when running on the Z resonance – especially resistive wall, beam-beam, and electron cloud –, the beam lifetime, dynamic aperture, alignment tolerances, and beam-based alignment. For the booster, the primary concern is the vacuum system, with regard to impedance and effects of the residual gas. For the injector, the layout and the linac repetition rate are primary considerations. We discuss the various issues and report the planned mitigations.
Paper: WEPR14
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR14
About: Received: 11 May 2024 — Revised: 18 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPR15
Testing electron polarization at SuperKEKB using Touschek lifetimes
2497
The Chiral Belle project is a proposed project which aims to expand the capabilities of SuperKEKB and the physics goals of Belle II by injection polarized electrons into the High Energy Ring. Before the full implementation of spin rotator magnets near the interaction point, we propose to demonstrate the injection and transport of polarized electrons in the SuperKEKB Main Ring. By measuring the effect of differing polarization states on the Touschek lifetime, we aim to show the preservation of polarized spin vectors around the main ring without the need for the full apparatus of Compton polarimetry and spin rotator magnets which will be required for the full Chiral Belle project.
Paper: WEPR15
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR15
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPR20
Probing FCC-ee energy calibration through resonant depolarization at KARA
2516
The FCC-ee collider physics program requires a precise determination of the center-of-mass energy. The average energies of the two colliding beams can be measured by resonant depolarization (RDP) of polarized electron and positron bunches. The depolarization is achieved by an electromagnetic device, e.g., a strip line, excited at a sweeping frequency. Once the excitation frequency is equal to the spin precession frequency, which is directly proportional to the beam energy, the polarization is lost or reduced. At KARA the resonant frequency is routinely measured via the change of the Touschek lifetime. We report on an RDP beam measurement campaign at the Karlsruhe Research Accelerator (KARA), exploring how this technique could be applied at the FCC-ee. In particular, we examine the sensitivity of the inferred value of beam energy to various parameters, such as the depolarize scan speed, the scan direction, and the beam operation energy.
Paper: WEPR20
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR20
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPR27
FLUKA simulations of neutrino-induced effective dose at a Muon Collider
2540
During the operation of a muon collider in an underground tunnel, most circulating muons decay into an electron (or positron) and a neutrino-antineutrino pair, resulting in a narrow disk of high-energy neutrinos emitted radially in the collider plane and emerging on the Earth’s surface at distances of several km. Thus, dedicated studies are required to assess any potential radiation protection risks to the public due to the interaction of such neutrinos near the surface. This work presents a set of FLUKA Monte Carlo simulations aimed at characterizing the radiation showers generated by the interactions of high-energy neutrinos from TeV-scale muon decays in a reference sample of soil. The results are expressed in terms of effective dose in soil at different distances from the muon decay, quantifying the peak dose and the width of the radiation cone, for beam energies of 1.5 TeV and 5 TeV. The implications of these results for realistic muon collider scenarios are discussed, along with possible methods to mitigate the local neutrino flux.
Paper: WEPR27
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR27
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPR31
Introducing a semi-Gaussian mixture model for simulating multiple coulomb scattering in RF-track
2556
Within the context of a design study of a LINAC for ionization cooling, this paper presents the result of incorporating a scattering model in RF-Track (v2.1) for charged particles heavier than electrons. This inclusion enables simulations for applications like ionization cooling channels for muon colliders. Within RF-Track, a novel semi-Gaussian mixture model has been introduced to describe the deflection of charged particles in material. This innovative model comprises a Gaussian core and a non-Gaussian tail function to account for the effects of single hard scattering. To validate the accuracy of our results, we conducted a benchmarking comparison against other particle tracking codes, with the outcomes demonstrating a high level of agreement.
Paper: WEPR31
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR31
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPR36
Low-energy muon and muonium beam source at Fermilab
2568
We describe a high-efficiency source of muonium that can be transported as a beam in vacuum provides opportunities for fundamental muon and precision physics measurements such as sensitive searches for symmetry violation. Although PSI is currently the world leader, the intense 800-MeV PIP-II linac beam at Fermilab could provide world-class low-energy muon and muonium beams, with unparalleled intensity, driving the next generation of precision muon-based physics experiments at the intensity frontier. However, it is critical to initiate the prerequisite R&D now to prepare for the PIP-II era. A low-energy secondary muon line recently installed in an operating facility (the MeV Test Area, which utilizes the intense 400-MeV Fermilab Linac beam) could support the required R&D, and potentially compete for new physics in the immediate term, if approved. This beamline was developed for μ– and will need to be re-optimized for surface μ+ production and transport, making it also suitable for muon spin rotation physics––a unique research and industrial application for which no U.S. facility exists, and whose facilities are oversubscribed worldwide.
Paper: WEPR36
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR36
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPR37
The European Spallation Source neutrino super beam
2571
The discovery of neutrino Charge-Parity Violation (CPV) became an important candidate to explain the matter dominance in the Universe. The goal of the ESSnuSB project is to discover and measure neutrino CPV with unprecedented sensitivity*. The construction of the European Spallation Source, ESS, the world’s most intense proton source, represents an outstanding opportunity for such project to take place. ESSnuSB has been granted from EU in the framework of H2020 (2018-2022) and Horizon Europe (2023-2026) to make Design Studies. The aim of the first Design Study was to demonstrate that the ESS linac can be used to generate an intense neutrino beam by doubling its average beam power and that a megaton water Cherenkov detector can be constructed in a mine 360 km from ESS providing detection of neutrinos at the 2nd neutrino oscillation maximum. A CDR** has been published in which it is shown the high physics performance to discover CPV and precisely measure the violating parameter δCP. For this, the modification for neutrino generation to compress the proton pulse length from 2.86 ms, to 1.3 μs has been studied. The second, ongoing, Design Study, ESSnuSB+, is devoted to neutrino cross-section measurements relevant to the CPV discovery. Two facilities are proposed, a low energy nuSTORM (muons decaying to neutrinos in a race-track storage ring) and low energy ENUBET (pions decaying to a muon and a neutrino, allowing the neutrino beam to be monitored by detection of the decay muon).
Paper: WEPR37
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR37
About: Received: 14 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPR43
Experimental evidence of the effect of transverse Landau damping on the microbunching instability
2590
The mechanisms that drive short-range modulations in the longitudinal phase space of accelerated electron bunches, otherwise known as the microbunching instability, have undergone intensive study. The various collective interactions between charged particles within the bunch, and their environment, can degrade the quality of these bunches, eventually making them unsuitable to drive light sources such as free-electron lasers (FELs). Although the most common method for removing this instability at X-ray FELs – namely, the laser heater – has proven to be very useful in improving the performance of these facilities, alternative methods to achieve this goal are active areas of research. In this contribution, we present experimental evidence of the influence of transverse Landau damping on mitigating the microbunching instability.
Paper: WEPR43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR43
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPR49
Near-infrared noise in intense electron beams
2608
Requirements for the noise in electron beams (NEB) have recently approached the Shot-noise level in some new applications. The density fluctuations of intense beams in the near-infrared (NIR) region are being measured at the Fermilab Accelerator Science and Technology (FAST) facility. The main goal of the experiment is to accurately compare the Shot-noise model with the observations of optical transition radiation (OTR) generated by the gamma=63 electron beam transiting an Al metal surface. In addition, evidence for longitudinal-space-charge-induced microbunching for the chicane-compressed beam was obtained with coherent enhancements up to 100 in the various bandwidth-filtered NIR OTR photodiode signals. With micropulse charges up to 1 nC, the beam parameters are close to those proposed for a stage in an Electron-Ion Collider (EIC) with coherent electron cooling (CEC). In this paper we present the current progress of the NEB project and compare the low electron energy measurements with ImpactX simulations.
Paper: WEPR49
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR49
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
WEPR57
Simulations of incoherent effects driven by electron clouds forming in the inner triplets of the Large Hadron Collider
2627
During Run 2 and Run 3 of the Large Hadron Collider (LHC), slow losses from electron cloud (e-cloud) effects have been systematically observed during the full duration of fills with closely-spaced proton bunches. In particular, these effects had been found to depend strongly on the crossing angle of the two beams and the value of the betatron functions in the interaction points. Due to this observation, the main cause of this effect was attributed to the non-linear forces induced by electron clouds forming in the vacuum chamber of the LHC Inner Triplet quadrupole magnets. In this contribution, electron cloud buildup simulations reveal that the induced forces depend strongly on the transverse coordinates of the beam particles, on time, as well as on the longitudinal coordinate within the Inner Triplet. Finally, non-linear maps are generated based on the buildup simulations, and the effect of these forces on the motion of the protons is simulated.
Paper: WEPR57
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR57
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPR58
Status of the time-dependent FEL code Genesis 1.3
2631
Version 4 of the widely used time-dependent FEL code Genesis 1.3 has been released. The C++ code keeps the entire bunch in memory and thus allows for self-consistent effects such as wakefields or long-range space charge fields. With sufficiently allocated distributed memory, Genesis 1.3 can represent each individual electron. This solves the problem of the shot noise statistics at any arbitrary frequency in the simplest way and allows for sorting and redistribution of particles among the computer cores for advanced FEL applications such as the Echo-Enabled Harmonic Generation schemes. This presentation reports on the new physics added to the code as well as features which simplify the setup of the simulations as well and the ability to link user-made libraries to adapt to the specific needs of each user.
Paper: WEPR58
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR58
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPR59
Developing nested auto-differentiation tracking code for beam dynamics optimization
2635
An innovative particle tracking code is in development using the Julia programming language, utilizing the power of auto-differentiation (AD). With the aid of specifically designed truncated power series algebra (TPSA) methods and built-in Julia AD packages, this code enables automatic calculation of derivatives with respect to selected parameters of interest. This tracking code provides a flexible and powerful solution for accelerator physicists applicable across various research topics, especially for beam dynamics optimization works.
Paper: WEPR59
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR59
About: Received: 13 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPR67
Temperature, density of states, and thin film optical effects on electron emission from semiconductor photocathodes
2660
Increasing the brightness of electron beams emitted from photocathodes will allow X-ray Free Electron Lasers (XFELs) to lase at larger photon energies with higher pulse energies. This will enable the development of key new accelerator capabilities. Higher electron beam brightness can be achieved by creating photocathodes with high quantum efficiency (QE) and/or low intrinsic emittance. Results from recent experiments demonstrated that QE can be increased 2 to 5 times by optical interference absorption effects in specifically layered materials compared to conventionally grown photocathodes. We have developed models for electron emission from thin film semiconductor photocathodes that include optical interference effects and show similar increase in QE for alkali-antimonide and cesium-telluride photocathodes. Here, we extend these models to include temperature and density of states effects on electron emission. We present results from these models on both QE and intrinsic emittance and discuss possible ways to increase the brightness of electron beams emitted from thin film semiconductor photocathodes.
Paper: WEPR67
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR67
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPR73
C-band high-gradient linac design considerations for HPC modeling
2676
Linacs are an integral part of high-gradient accelerating structures for X-ray Free Electron Laser (XFEL) facilities. For high energy (42+ keV) x-rays, this translates into a longer linac (linear accelerator), which in turn translates into increased cost due to the larger footprint. One such case is the DMMSC (Dynamic Mesoscale Material Science Capability) at Los Alamos National Laboratory. C-band devices are an attractive option, as they offer suitable electron beam properties and are significantly smaller than conventional L- or S- band structures. This need for state-of-art designs dictates increasingly complex structures such that CPU-intensive simulations are now a key part of accelerator component design. As that happens, high performance computing (HPC) becomes a necessary component of the design process. The Argonne Leadership Computing Facility offers a route to rapid design evaluation through successive simulations while varying, for example, geometric features and particle beam properties.
Paper: WEPR73
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR73
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPR74
Electron cloud simulations in the Fermilab booster
2680
As part of Fermilab's Proton Improvement Plan-II (PIP-II), the Fermilab Booster synchrotron will operate at a higher intensity, increasing from 4.5×10^12 to 6.7×10^12 protons per pulse (ppp). A potential challenge for achieving high-intensity performance arises from rapid transverse instabilities induced by electron clouds (EC). This research presents electron cloud simulations using PyECLOUD, which is an advanced computational tool that incorporates measurements of the secondary electron yield (SEY) from the Booster's combined function magnet material. By systematically varying beam parameters in PyECLOUD, such as bunch structure, SEY, bunch length, and intensity, it becomes possible to forecast the impact of EC effects on the beam stability of the PIP-II era Booster.
Paper: WEPR74
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR74
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPS03
Hybrid plasma generator for high intensity fast pulsed ion sources
2694
The main challenge in the development of high intensity ion sources is, besides the space charge limited extraction, the available plasma density. Conventional plasma generators use e.g. arc discharge plasmas or RF generated plasmas. Preliminary tests are carried out on both types of plasma generators and plasma parameters are determined to create a basis for evaluation. A concept is being developed that combines the advantages of both types. This hybrid plasma generator will also be investigated in terms of plasma parameters in order to test a possible application for high intensity ion sources. Further the proposed plasma generator has the property that due to a permanently available low-density RF plasma a faster build-up of the highly dense arc discharge plasma may be achieved. The properties of the concept with regard to a fast plasma build-up time are being investigated in order to test a possible application for the fast pulsing of high intensity ion sources.
Paper: WEPS03
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS03
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPS13
Prototype and high-power test of SiC HOM
2723
The Electron Ion Collider (EIC), to be built at BNL, is a unique high-energy, high-luminosity, polarized electron-proton/ion collider. High-Order-Mode (HOM) damping is a big challenge for EIC electron accelerators, especially for 17 single-cell 591 MHz SRF cavities in EIC Electron Storage Ring (ESR) because of its high electron beam current (up to 2.6 A). Room temperature SiC Beamline HOM absorbers (BLA) were chosen as the baseline of the HOM absorber, due to its broadband and high power capability. A SiC HOM absorber was prototyped to test a preparing process and high power handling capability. The high power test demonstrates 0.3 W/mm^2 of power handing capability by far, and we are going higher power to test its limit. This paper will present the preparing process (shrink fit, cleaning and outgassing test) and high power test results of the SIC HOM absorber prototype.
Paper: WEPS13
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS13
About: Received: 09 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPS14
Progress on high power FPC development for EIC
2727
The Electron-Ion Collider (EIC) requires 34, 500 kW continuous-wave (cw), 591 MHz Fundamental Power Couplers (FPCs) to compensate the Electron Storage Ring’s (ESR) 10 MW of synchrotron radiation and other beam driven losses. This paper will describe the FPC design and fabrication status, particularly the technical challenges associated with 500 kW cw operation and the innovative design addressing this. Of important note, the RF window based on 99.5% purity alumina window was designed to be wide operating bandwidth, which makes it applicable to FPCs for the EIC’s RF systems outside of the ESR with frequencies ranging from 197 MHz-591 MHz. This results in significant savings by eliminating the need to design multiple different RF windows for the different RF systems. This paper will describe the design and prototype progress of the High Power FPC for EIC.
Paper: WEPS14
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS14
About: Received: 09 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPS17
Low RF loss DC conductive ceramic for RF windows
2733
Charging of RF windows has historically been problematic, frequently resulting in damage to the window severe enough that the window needs to be replaced. Many attempts have been made to prevent charging and therefore improve window lifetime, the most successful and common of which is coating the window with titanium nitride (TiN). Surface coatings such as TiN rely on the secondary electron yield of the coating material being lower than that of the ceramic window material, reducing the number of electrons emitted from a variety of mechanisms. An alternative approach is to introduce a small amount of DC conductivity to the ceramic itself, turning the traditionally insulating window into a mildly conductive one. This allows any charge on the surface of the window to drain rather than build until a discharge happens. A magnesium titanate ceramic has been developed with a small DC conductivity and used to make RF windows. Several window assemblies have been produced and tested, including 1.3 GHz waveguide and 650 MHz coaxial designs. The results of the conductive ceramic window test program will be presented.
Paper: WEPS17
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS17
About: Received: 16 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPS21
Coupler HV bias studies on ESS elliptical cavities
2743
We study the effects of high voltage DC bias on the fundamental power couplers of the ESS elliptical SRF cavities. These tests were carried out at the TS2 facility, where cryomodule acceptance and characterization tests are carried out. We present the observed effects of positive and negative bias field on multipacting in the RF couplers, as well as the implications for operation in the ESS linac.
Paper: WEPS21
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS21
About: Received: 17 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPS28
Study of the generalized electron emission theory in a superconducting cavity
2757
Research is being conducted on field emission, thermionic emission, generalized electron emission, and electron emission from superconducting cavities. Generalized electron emission theories, which encompass field emission and thermionic emission, are currently under investigation. In field emission, electrons are emitted from metals due to a strong local electric field, while in thermionic emission, electrons are emitted due to high local temperatures. Field emission is being explored in relation to dimensions, and thermionic emission is likewise examined as a function of dimensions. The distribution of the electric field is illustrated over surface curvature. Furthermore, field emission characteristics are specifically analyzed within the context of superconducting RF cavities.
Paper: WEPS28
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS28
About: Received: 11 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPS32
Superconducting thin films for higher order mode antennas to increase the CW performance of SRF cavities at MESA
2760
The Mainz Energy-Recovering Superconducting Accelerator (MESA), an energy-recovering (ER) LINAC, is currently under construction at the Institute for Nuclear physics at the Johannes Gutenberg-Universität Mainz, Germany. In the ER mode continues wave (CW) beam is accelerated from 5 MeV up to 105 MeV. The energy gain of the beam is provided through 2 enhanced ELBE-type cryomodules containing two 1.3 GHz 9-cell TESLA cavities each. By pushing the limits of the beam current up to 10 mA, a quench can occur at the HOM Antennas. The quench is caused through the increased power deposition induced by the electron beam in ER mode. Calculation shown that an upgrade from 1 mA to 10 mA is increasing the deposited power in the HOMs up to 3080 mW. 30% of this power will be out coupled with the HOM couplers and can be used as a thermal input. Simulations show a power limit of 95 mW which includes the power for 1 mA but is exceeded at 10 mA. A solution to increase the power limit are superconducting thin films which provides higher critical fields, temperature and currents. As candidates are Nb3Sn and NbTiN are chosen. First simulations of the power limit for coated HOM antennas are shown.
Paper: WEPS32
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS32
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPS56
Design and prototyping of the Electron Ion Collider electron storage ring 591 MHz elliptical SRF cavity
2818
The electron storage ring (ESR) in the Electron Ion Collider (EIC) requires a challenging 591 MHz fundamental 17-cavity RF system to provide up to 10 MW CW power to the beam with up to 2.5 A beam current and a wide range of voltage. In this paper, we will report the latest RF and mechanical design status, as well as the prototyping and testing results.
Paper: WEPS56
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS56
About: Received: 18 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPS61
Mapping the stray magnetic field at the Relativistic Heavy Ion Collider tunnel
2836
A new Rapid Cycling Synchrotron (RCS) [1] is designed to accelerate the electron bunches from 400 MeV up to 18 GeV for the Electron Ion Collider (EIC) [2] being built at Brookhaven National Laboratory (BNL). One of the two Relativistic Heavy Ion Collider (RHIC) rings will serve as the Hadron Storage Ring (HSR) of the EIC. Beam physics simulations for the RCS demonstrate that the electron beam is sensitive to the outside magnetic field in the tunnel. Significant magnetic fields are expected due to the HSR and the Electron Storage Ring (ESR) being at full energy during the RCS operation. The earth magnetic field at the location of the RCS center was measured throughout the circumference of 3870 m tunnel without RHIC operation. In addition, the fringe magnetic field from RHIC magnets at several locations during RHIC operation was measured and compared with simulation at different ramping currents. A robotic technology is being developed to automatically measure the stray magnetic field at any location during the RHIC (or future EIC) operation.
Paper: WEPS61
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS61
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THXN1
High gradient RF photoinjector at LANL
2916
High frequency RF guns cryogenically cooled to liquid nitrogen temperatures or lower offer potential for extreme accelerating electric fields exceeding 250 MV/m at the cathode. This can result in enormous increase in the brightness of electron beams obtained from RF guns but can be challenging to integrate high QE photocathodes. This talk will detail the efforts at LANL towards the realization of such a gun and possibly the first field and beam results from a C band room temperature gun.
Paper: THXN1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THXN1
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THYD1
Coherent electron cooling physics for the EIC
2937
In order to prevent emittance growth during long stores of the proton beam at the future Electron-Ion Collider (EIC), we need to have some mechanism to provide fast cooling of the dense proton beams. One promising method is coherent electron cooling (CeC), which uses an electron beam to both ``measure'' the positions of protons within the bunch and then apply energy kicks which tend to reduce their longitudinal and transverse actions. In this work, we discuss the underlying physics of this process. We then discuss simulations which constrain the electrons to move only longitudinally in order to perform fast optimizations and long-term tracking of the bunch evolution, and benchmark these results against fully 3D codes. Additionally, we discuss practical challenges, including the necessity of a high-quality electron beam and sub-micron alignment of the electrons and protons.
Paper: THYD1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THYD1
About: Received: 15 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
THPC05
Experimental measurement of the second-order transit time factor in a single-cell RF cavity for relativistic electron beams
2971
In this paper, we present a concise measurement of the Second-Order Transit Time Factor(TTF) of the relativistic electron beams within the bunching cavity of the Coherent Electron Cooling (CeC) Pop Experiment. Our study outlines a specialized measurement methodology that tackles the unique challenges posed by the CeC accelerator environment. The results not only provide significant insights into controlling CeC beam dynamics but also critically validate the theoretical prediction of the Second-Order TTF for relativistic electron beams. This work advances our understanding of beam dynamics and enhances the efficiency and control of CeC-based systems.
Paper: THPC05
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC05
About: Received: 21 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPC06
IMPACT-T simulation for the latest coherent electron cooling pop experiment
2974
This paper presents the results of the IMPACT-T simulation conducted for the latest iteration of the Coherent Electron Cooling (CeC) Pop Experiment at Brookhaven National Laboratory (BNL). The CeC experiment aims to demonstrate the principles of CeC, a rapid cooling technique designed for high-energy hadron beams. In addition to presenting simulation results for the current lattice parameters, this paper includes a discussion of previous benchmarking results obtained from IMPACT-T simulations and real CeC experiments. These comprehensive simulations not only facilitate the fine-tuning of CeC lattice parameters but also offer insights into the ongoing performance enhancements, all aimed at achieving exceptional beam quality.
Paper: THPC06
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC06
About: Received: 13 May 2024 — Revised: 22 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
THPC09
Pulsed correctors for the beam vertical stability during injection in CESR
2982
Beam motion during injections could be a serious problem to x-ray users and jeopardize their experiments. In the Cornell Electron Storage Ring (CESR) the particles are injected with pulsed elements such as pulsed bumpers and septum which could cause transient motion of the stored beam. By analyzing the turn-by-turn position data of the stored beam acquired during injection, we identify the source of beam motion in different time scales. A new corrector coil is then designed to compensate the beam motion with 0.15 msec duration at a 60 Hz repetition rate in the vertical plane. In addition to the new corrector we also use one of the existing magnet coils to correct 60 Hz kicks and DC offsets. Although, during the last summer down the 60 Hz source was identified and suppressed by an order of magnitude, this corrector is still in use to minimize the injection transient. The waveforms, used to drive the correctors, are extracted based on the beam turn-by-turn coordinates and orbit kick analyses using the 110 CESR Beam Position Monitors data. In this paper we discuss the requirements and parameters of the new corrector, as well as the correction technique, which is proven to be effective.
Paper: THPC09
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC09
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPC25
Transmission characteristics of dark current in UED
3035
The high gradient of the photocathode radio-frequency electron gun (RF gun) increases the potential for field emission from the metal surface. Consequently, emitted electrons escaping from the RF gun result in the generation of a dark current, thereby degrading the gun's performance. A thorough investigation into the dark current phenomenon within the accelerator structure plays a crucial role in assessing the performance of the RF cavity and cathode, ensuring the accelerator operates under normal conditions. This paper focuses on establishing a transport matrix for off-axis particles in the RF gun and solenoid. This matrix predicates that field-emitted electrons tend to deviate from the center of the cathode. The study delves into both transverse and longitudinal dynamics characteristics of particles. By numerically tracking the path of dark electrons, we achieved a notable alignment between theoretical prediction and simulation results.
Paper: THPC25
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC25
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPC27
Quasi-isochronous conditions and high order terms of momentum compaction factor at the compact storage ring
3039
The compact storage ring project for accelerator research and technology (cSTART) is realized at the Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology (KIT). Flexible lattice of a ring benefits variety of operation modes. Different physical experiments are planned at cSTART. In particular, deep variation of momentum compaction factor with simultaneous control of high order terms of alpha would demonstrate the capture and storage of ultra-short bunches of electrons in a circular accelerator. Computer studies of linear and non-linear beam dynamics were performed with an objective to estimate arrangement and performance of dedicated three pole chicane magnets to provide quasi-isochronous conditions for electrons. Additional families of so called “longitudinal” sextupoles and octupoles were added in a ring model to control slope and curvature of momentum compaction factor as function of energy offset of particles in a bunch.
Paper: THPC27
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC27
About: Received: 03 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPC28
Design of the H- beamline for the LANL RFQ test stand
3043
The Los Alamos Neutron Science Center (LANSCE) accelerator produces high intensity H+ and H- beams for multiple experiments in fundamental and national security science. The proposed LANSCE Modernization Project (LAMP) is evaluating necessary upgrades to enable continuous LANSCE operations in years to come. LAMP seeks to upgrade the H+ and H- 750 kV Cockcroft-Walton (CW) generators with a dual-beam, 3-MeV Radiofrequency Quadrupole (RFQ). For technology maturation and know-how associated with this concept, an RFQ test stand with LAMP-like layout is being set-up to demonstrate dual-beam operation in an RFQ with all beam patterns required by experiments. The RFQ test stand will have 35-keV H+ and H- beamlines that simultaneously inject into a 750 keV RFQ. Assembly and initial characterization of the H+ beam is under way. The H- beamline has stringent requirements and will also demonstrate systems like a beam chopper and a low frequency buncher to produce required beam patterns. We describe the design of the H- beamline based on accelerator codes Warp and Impact.
Paper: THPC28
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC28
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPC33
Simulation of longitudinal phase space measurements for the RUEDI ultrafast electron diffraction beamline
3060
The RUEDI (Relativistic Ultrafast Electron Diffraction & Imaging) ultrafast electron diffraction (UED) beamline aims to provide electron bunches to diffraction samples with an at-sample temporal resolution of sub-10 fs. Electron bunches of such short duration prove non-trivial to measure at electron beam kinetic energies of 4 MeV. A diagnostic beamline design is presented to enable simultaneous longitudinal phase space measurements (bunch duration, momentum and momentum spread) with a streaker and spectrometer. Several methods of measuring sub-10 fs bunch durations using both RF transverse deflecting cavities and THz streakers are outlined here with their limitations. Measurements are replicated in simulation to demonstrate the diagnostic beamline is capable of the high-resolution required for the longitudinal phase space measurements within the RUEDI UED beamline.
Paper: THPC33
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC33
About: Received: 13 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPC38
Exploratory splitter bend system designs for FFA@CEBAF
3079
An upgrade to the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility (JLAB) is anticipated to provide an electron beam of over 20 GeV using the existing superconducting-RF linear accelerator and new fixed-field alternating (FFA) gradient recirculation arcs made up of Halbach-style permanent magnets. In the current design, the FFA arcs will carry six beams with energies of approximately 11, 13, 16, 18, 20, and 22 GeV which will require horizontal splitter lines to match the beam from the preceding linac. In this paper, we describe two alternative splitter beamline designs that are tuned to match the beam's Twiss parameters, R56, time-of-flight, bend-plane offset, and dispersion into the FFA cells.
Paper: THPC38
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC38
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPC40
Development of an ERL for coherent electron cooling at the Electron-Ion Collider
3086
The Electron-Ion Collider (EIC) is currently under development to be built at Brookhaven National Lab and requires cooling during collisions in order to preserve the quality of the hadron beam despite degradation due to intra-beam scattering and beam-beam effect. An Energy Recovery Linac (ERL) is being designed to deliver the necessary electron beam for Coherent electron Cooling (CeC) of the hadron beam, with an electron bunch charge of 1 nC and an average current of 100 mA; two modes of operation are being developed for 150 and 55 MeV electrons, corresponding to 275 and 100 GeV protons. The injector of this Strong Hadron Cooler ERL (SHC-ERL) is shared with the Precooler ERL, which cools lower energy proton beams via bunched beam cooling, as used in the Low Energy RHIC electron Cooling (LEReC). This paper reviews the current state of the design.
Paper: THPC40
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC40
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
THPC45
EIC impedance and beam dynamics
3094
A new high-luminosity Electron-Ion Collider (EIC) is being developed at BNL. Beam collisions occur at IP-6, involving two rings: the Electron Storage Ring (ESR) and the Hadron Storage Ring (HSR). The vacuum system of both rings is newly developed and impedance optimization is progressing. Beam-induced heating and thermal analysis are performed for both rings to manage and control thermal distribution. The study explores collective effects across the Rapid Cycling Synchrotron (RCS), ESR, and HSR using simulated single bunch wakefields. Discussions encompass impedance analysis, collective effects and beam interactions, and the impact of ion and electron clouds on beam dynamics.
Paper: THPC45
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC45
About: Received: 13 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPC48
Impedance calculation for the hadron storage ring in the Electron-Ion Collider with ECHO3D
3104
ECHO3D has been used for calculating the geometric impedance for several beamline vacuum components in the hadron storage ring (HSR) of the EIC (Electron-Ion Collider) in the past few years. In this paper, we present the geometric impedances calculated from ECHO3D for the beam screen with pump slots, the polarimeter and the bellow with pump ports in the HSR. We also discuss some findings while cross-checking these results with what calculated from GdfidL and CST.
Paper: THPC48
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC48
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPC56
Simulation of beam loading compensation with RF-Track
3136
The beam loading effect results in a gradient reduction of the accelerating structures due to the excitation of the fundamental mode when the beam travels through the cavity. A recent implementation of this process in the tracking code RF-Track allows the simulation of realistic scenarios, thus revealing the impact of this phenomenon in start-to-end accelerator designs. In this paper, we present the latest update of the beam loading module which allows the simulation of the compensation of this effect and we explore the potential of the developed tool in heavy-loaded scenarios.
Paper: THPC56
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC56
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPC70
GSI electron lens for space charge compensation
3186
The electron lens for space charge compensation is an R&D project to increase the primary beam intensity and thus the accelerator efficiency of SIS18 and eventually SIS100 for FAIR operation. As a first step, the principle of space charge compensation will be demonstrated in SIS18 with a single lens, aiming at a tune shift of 0.1 for several ion species. However, the design should also be compatible with the SIS100. Following the conceptual design studies, a technical design of the electron lens has been prepared and the main components of the electron lens are currently under development. This contribution gives an overview of the development of the electron lens, with particular emphasis on the main lens components and the studies carried out on the dynamics of the ion beam.
Paper: THPC70
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC70
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
THPC73
Combined wakefield and beam-beam effects in the EIC design
3198
Collective wakefield and beam-beam effects play an important role in accelerator design and operation. These effects can cause beam instability, emittance growth, and luminosity degradation, and warrant careful study during accelerator design. In this paper, we report on the development of a computational capability that combines both short and long range wakefield models and a strong-strong beam-beam simulation model. Applications to the EIC will be discussed.
Paper: THPC73
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC73
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
THPC76
Discussion of space charge effects of a beam train containing infinitely many bunches
3210
In an electron linear accelerator, the continuous beam emitted by an electron gun will become an equally spaced beam train after passing through the bunching section. If the current of the beam is large, its expansion may be more intense than the case where only a single bunch is considered, resulting from the space charge forces between different bunches. In this article, using an algorithm capable of calculating the space charge effects of a beam train containing infinitely many bunches with uniform spacing, we compare bunch trains with different parameters to find the pattern of their space charge effects.
Paper: THPC76
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC76
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPG02
Performance optimization design of photocathode injector based on multi-objective genetic algorithm
3244
Generating beam with nC-level charge is of great significance for particle colliders. In order to achieve lower emittance and length of bunch, based on the photocathode injector, we designed a L-band gun and L-band accelerating tube. However, with many coupled parameters, it is difficult to optimize its performance to the limit when optimizing them separately. Therefore, we employed a multi-objective genetic algorithm for searching in the multi-dimensional parameter space and utilized a deep Gaussian process as a surrogate model to solve the high-dimensional parameter optimization problem. Through optimization, we successfully obtained the normalized transverse emittance of 3.4 π mm·mrad and the bunch length of 1.0 mm for a fixed charge of 5 nC. This indicates that our method can effectively improve the performance of the photocathode injector.
Paper: THPG02
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG02
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPG03
Temporal profile shaping for a dispersive section using a multi-objective genetic algorithm
3247
Our research focuses on the design of a beamline. Due to the numerous beamline components involved, without strict optimization of each component's parameters, the transmitted temporal profile of beam may distort, failing to meet the expected requirements. Additionally, different initial temporal profile of the beam will undergo longitudinal shaping during transmission through the beamline. Therefore, we aim to determine the combination of initial beam temporal profile at the cathode and the parameters of the beamline components based on the specific beam distribution at the exit. We propose the application of an improved multi-objective genetic algorithm to solve this problem. Through multiple optimization iterations for a given temporal profile, our algorithm consistently identifies multiple suitable combinations of initial beam temporal profile and beamline component parameters to produce the desired specific temporal profile of the beam.
Paper: THPG03
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG03
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPG04
RF and multipactor analysis for the CARIE RF photoinjector with a photocathode insert
3251
At Los Alamos National Laboratory (LANL), we developed a 1.6-cell C-band RF photoinjector for the Cathodes And Radiofrequency Interactions in Extremes (CARIE) project. The injector will be used to study the behavior of advanced photocathode materials under very high RF gradients. The photocathodes will be prepared with an INFN-style photocathode plug, compatible with the plugs used by other institutions. This presentation will report the RF design of the photoinjector with distributed coupling and RF field symmetrization. Beam physics simulations show that symmetrized RF fields in the vicinity of the beam axis are essential for minimizing the normalized emittances for a 250-pC electron bunch. We will also present the design for the photocathode insertion and the analysis of the challenges related to reducing the peak electric fields, multipactor suppression, and resonant frequency tuning by fine adjustment of the plug position.
Paper: THPG04
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG04
About: Received: 14 May 2024 — Revised: 16 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
THPG08
Development of a non-linear injection kicker for the TPS storage ring
3264
The TPS storage ring adopts a standard four kickers bump off-axis injection. This scheme is known to disturb stored beam during injections. The non-linear kicker injection concept provides a possible solution to facilitate top off injection with minimizing the oscillation of the stored beam. This non-linear kicker has zero Bx and By field in the center and an off-axis By displaced by 15 mm for TPS case. In this paper, we present the magnetic circuit design, consideration, fabrication, and first field measurement results of the TPS non-linear injection kicker.
Paper: THPG08
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG08
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
THPG10
Energy selection of synchrotron booster for SLRI beam test facility
3268
The SLRI Beam Test Facility (SLRI-BTF) is able to produce electron test beam with maximum energy of 1.2 GeV and various intensities from a few to millions of electrons per repetition. The main components of the SLRI-BTF are the Siam Photon Source (SPS) injector consisting of a 40-MeV linear accelerator, a low-energy transport beamline, a synchrotron booster increasing electron energy to 1.2 GeV, and a high-energy transport beamline. As the SLRI-BTF has successfully utilized the electron test beam to characterize pixel sensors for high-energy particle detectors and to perform high-energy electron irradiation, the test beam with lower energy ranges has also been requested by users. In this work, the test beam with lower energy can be obtained by changing the acceleration pattern of the SPS booster and adjusting high-energy transport beamline to match the extracted beam energy. Production of test beam with lower energy can be confirmed by test beam measurement at the SLRI-BTF experimental station.
Paper: THPG10
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG10
About: Received: 12 May 2024 — Revised: 19 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPG11
Long range plasma experiment beam transport with UCLA MITHRA beam line
3271
This study focuses on developing beam-matching optics for the transport of the MITHRA beam into plasma to study long range plasma effects. To ensure successful injection into the plasma chamber, matching conditions are crucial at the entrance. A dedicated focusing system, comprising beam-matching optics, is designed to transport the beam from the 1.5-meter linear accelerator (linac) and align the necessary parameters at the plasma entrance. Optimization simulations employing Elegant and General Particle Tracer (GPT) codes, based on MITHRA gun data, have been conducted with promising results that align with our expectations. Further investigations involve simulating the PWFA interaction using advanced, fully relativistic, three-dimensional Particle-in-Cell (PIC) codes, namely OSIRIS and QuickPIC.
Paper: THPG11
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG11
About: Received: 16 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPG29
A multi-variable approach to mid-ranging control for unified operation of fast and slow correctors in fast orbit feedback system
3314
Advanced Photon Source Upgrade (APS-U) Fast Orbit Feedback (FOFB) system uses 160 fast and 160 slow corrector magnets to stabilize orbit measured at 560 Beam Position Monitors (BPM). We plan to operate both fast and slow correctors in a unified feedback algorithm at 22 kHz correction rate. Mid-ranging control is a proven approach for feedback systems with two manipulated inputs each exerting distinct dynamic effects to regulate a single output. This method resets the fast input to its chosen DC setpoint and proves beneficial when cost of fast input is more than the slower one. Unified operation of fast and slow correctors is a fitting application to mid-ranging concept which is well founded for two input one output systems. In this work, based on the cross-directional nature of the FOFB system we developed a multi-variable approach to mid-ranging control. It can be applied to FOFB with multiple fast and slow correctors, and multiple BPMs. Performance of proposed scheme is tested in simulations with APS-U FOFB prototype model in MATLAB. The feedback loop with fast and slow correctors is stable with mid-ranging algorithm, and the fast corrector drives effectively tracked setpoints.
Paper: THPG29
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG29
About: Received: 16 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPG42
Radiation levels in the LHC tunnel and impact on electronics during the 2023 Pb ion run
3355
The 2023 operation of the Large Hadron Collider (LHC) at CERN included a one-month-long run with fully stripped Pb ion beams, marking the first heavy-ion run since 2018, and delivering Pb ion collisions at an unprecedented center-of-mass energy of 5.36 TeV per nucleon pair. During this period, the radiation fields in the LHC tunnel have been measured by means of different radiation monitors, including Beam Loss Monitors (BLMs), RadMons, and distributed optical fiber dosimeters, with the primary goal of quantifying the radiation exposure of electronic systems. The radiation levels are driven by the Bound Free Pair Production (BFPP) and Electromagnetic Dissociation (EMD) processes taking place in all four interaction points, yielding significant radiation peaks in the Dispersion Suppressor (DS) regions of the tunnel. An overview of the radiation levels is presented in this contribution, with a special focus on the Insertion Region 2 (IR2) hosting the ALICE experiment, where a new collimator (TCLD) has been installed specifically for the ion run. The impact of radiation on the electronic systems and on the LHC availability during the run will also be discussed.
Paper: THPG42
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG42
About: Received: 08 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPG43
Assessment of the ratios of radiation sources and total electron loss at the injection section of the Taiwan Photon Source facility and total electron loss by using neutron measurements
3359
Radiation in the injection section of a synchrotron radiation facility is primarily the result of injection beam loss, which occurs each time the current is replenished, and storage beam loss, which accounts for the lifetime during routine operations. This study conducted neutron measurements by using high-sensitivity neutron detectors and obtained the total electron loss during the unfolding process. With the known lifetime, the ratio of injection beam loss to storage beam loss and the total loss in the injection section of the Taiwan Photon Source facility during routine operations were determined. The total electron loss at the measurement site was approximately five millionths of the full load current. The ratio of injection beam loss to storage beam loss was 1.64. The total electron loss was 0.44 pC, with 0.27 pC being attributed to injection beam loss and 0.17 pC being attributed to storage beam loss.
Paper: THPG43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG43
About: Received: 05 May 2024 — Revised: 16 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
THPG44
The LCLS-II beam loss monitor readout system
3362
The Linac Coherent Light Source II (LCLS-II) is a new addition to the SLAC accelerator complex. It is a 4 GeV, 120 kW superconducting Linac operating in continuous RF mode at 1.3 GHz with a beam repetition rate of up to 1 MHz. The prior generation of protection system beam loss monitors, whose operation is based on ion collection principles, are not suitable for operation in LCLS-II due to their slow recovery times. A new group of detectors have been identified and evaluated. These fall into three categories: Cherenkov detectors using optical fibers and photomultiplier pickups for distributed losses. Point detectors based on diamond pickups, and YAG:ce screens with photodiode pickups for burn through detection. These new detector elements require that new readout and signal processing electronics to be developed. In addition, because these detectors are part of the SLAC Beam Containment System (BCS), a certified safety system, a self-check mechanism is required to continuously verify the health of the detector and readout. This paper describes the design, operation and performance of the readout electronics.
Paper: THPG44
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG44
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
THPG46
Research on Monte Carlo model of radiation source in HLS storage ring
3369
Hefei Light Source (HLS) is the first dedicated synchrotron radiation facility in China. HLS-II operates in the TOP-OFF constant-current mode. For the safety of personnel, it is crucial to analyze the radiation fields applying Monte Carlo. The radiation source directly affects the results. The paper discusses the impact of three radiation source models on the radiation field results. In the first model, beam averaged losses over eight bend magnets. The second model assuming that there is a uniform loss at all beam pipes and bend magnets. The third model assumes that beam losses uniformly in a torus pipe. The radiation field during TOP-OFF constant-current of HLS-II storage ring was simulated applying FLUKA. The position and direction sampling equations were constructed for different radiation sources. Simulation results indicated that the dose rates of the second model was consistent to the torus uniform loss model. The calculation results of two models are in accord with the actual situation. As for the simulations on the radiation fields and radiation shield design in the storage ring, the torus radiation source with uniform loss is more convenient to operate.
Paper: THPG46
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG46
About: Received: 13 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
THPG47
Upgrade of LLRF control system for infrared free-electron laser
3372
Hefei Infrared Free-Electron Laser device (IR-FEL) is a user experimental device dedicated to energy chemistry research that can generate high brightness mid/far infrared lasers. It is driven by an S-band linear accelerator with a maximum electron energy of 60 MeV. The stability of the final output laser is determined by the energy stability and spread of the electron beam, and the Low-Level RF control system (LLRF) is opitimized to improve the energy stability of the electron beam. There are two klystrons in the linear accelerator of IR-FEL, and the periodic oscillation of out power output of the klytrons is existed (approximately ± 0.2%~2% for amplitude). The oscillation period of two klystrons are exchanged in the case of exchanging the filament power supplies of two klystrons. The pulse-to-pulse feedforward and in-pulse feedback algorithm are developed to compensate the periodic fluctuations of the output power of the klystrons, and the IQ demodulation is changed to the Non-IQ demodulation (13/3) to separate and suppress the odd harmonic. After the optimization, the stability of klystron output signal has been improved from 0.12%/0.07° (rms) to 0.04%/0.09° (rms).
Paper: THPG47
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG47
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPG50
Lifetime studies of magnet protection systems for the Large Hadron Collider at CERN
3378
In the architecture of the protection of the superconducting magnets of the Large Hadron Collider (LHC), systems such as Quench Heater Discharge Power Supplies (HDS), Local Protection Interface Module (LIM), Linear Redundant Power Supplies (LPR), and Power Packs (LPUS) are crucial. Thousands of these devices, some in operation since 2007, directly impact LHC’s availability and reliability. This paper delves into comprehensive lifetime studies on these critical systems. The methodology involves estimating their remaining operational lifespan through detailed analyses of failure modes, assessing electronic component criticality, accelerated aging of electrolytic capacitors, inspections, and irradiation tests at both component and system levels. The study concludes by presenting essential findings, including the estimated remaining lifetime of each equipment. Additionally, the paper recommends future developments to enhance system robustness, offering valuable insights for maximizing the longevity of these critical devices. This research significantly contributes to ensuring the sustained reliability and performance of the LHC's magnet protection systems.
Paper: THPG50
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG50
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPG67
Modernization of DARHT axis-I debris blocker
3428
The Dual-Axis Radiographic Hydrodynamic Test Facility (DARHT) uses a spinning wheel debris blocker as a crucial machine protection system to prevent target debris from the electron to X-ray conversion process from traveling upstream and damaging the accelerator. The spinning wheel in use on DARHT Axis-I consists of two spinning disks normal to the beamline, each with an open slit that crosses the beamline at frequencies of 50 Hz and 40 Hz, creating an opening at a beat frequency of 8 Hz allowing the electron beam to pass through and shut behind it. In this poster, we present steps taken to improve the reliability and performance of the spinning wheel, which include replacing legacy and custom diagnostic components with off-the-shelf hardware. We also present the challenges and solutions in testing and deploying these upgrades without disrupting operation of the accelerator.
Paper: THPG67
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG67
About: Received: 15 May 2024 — Revised: 10 Jun 2024 — Accepted: 10 Jun 2024 — Issue date: 01 Jul 2024
THPG68
Coupling of codes for modeling high-energy-density conditions in fourth generation light sources
3431
We present a method for coupling particle dynamics, particle-matter interaction, and hydrodynamics codes to model the effects of high-intensity electron beams in Fourth Generation Storage Rings for the purpose of machine protection. The coupled codes determine if high-energy-density conditions (>100 J/mm^3) are present in beam-intercepting components. Elegant is used to simulate the dynamics of a whole-beam abort by muting the high-power cavity RF. Within the APS-U, the impacting beam begins interacting with a horizontal collimator, at which point elegant is interrupted and the beam impact process is modeled using MARS and FLASH. MARS simulates the interaction of the beam with the collimator, passes the energy density to FLASH, and returns the transmitted particle distribution to elegant. FLASH uses the energy deposition to determine the density of the collimator material. The surviving beam is propagated again through the APS-U lattice and the process is repeated until the beam is fully lost. The input MARS geometry is updated each step to reflect the changing material properties. The coupled codes also examine the effects of synchrotron radiation within the vacuum beam chambers.
Paper: THPG68
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG68
About: Received: 16 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
THPR23
Towards mitigation of challenges in development of high power ISOL targets
3542
Worldwide Isotope Separation On-Line (ISOL) facilities face growing demand for producing and extracting high-purity exotic radioactive ion beams to serve nuclear physics, astrophysics and medical applications. In this technique, a particle beam interacts with a suitable target material to produce the desired isotopes through a combination of mechanisms like spallation, fragmentation and fission. TRIUMF has the world's highest-power ISOL facility—ISAC, handling 50 kW of proton beam power. The formidable challenge is to suitably handle the power deposited within the target material and maintain it at 2000°C to optimize the diffusion and effusion of the radioactive products. The intricacy of this design requires precise knowledge of the thermal properties of the target material. Typically, a blend of metallic carbide and graphite, these targets exhibit varying porosity and morphology and have effective thermal properties differing from individual constituent elements. To investigate these properties, a combined numerical-experimental approach is employed. This contribution discusses the optimization of target material sample size using numerical tools and outlines the exploration of thermal properties using an experimental apparatus, the Chamber for Heating Investigations (CHI), developed at TRIUMF.
Paper: THPR23
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR23
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPR35
Optimizing non-linear kicker injection parameters using machine learning
3571
Synchrotron light source storage rings aim to maintain a continuous beam current without observable beam motion during injection. One element that paves the way to this target is the non-linear kicker (NLK). The field distribution it generates poses challenges for optimizing the topping-up operation. Within this study, a reinforcement learning agent was developed and trained to optimize the NLK operation parameters. We present the models employed, the optimization process, and the achieved results.
Paper: THPR35
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR35
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPR37
Towards unlocking insights from logbooks using AI
3579
Electronic logbooks contain valuable information about activities and events concerning their associated particle accelerator facilities. However, the highly technical nature of logbook entries can hinder their usability and automation. As natural language processing (NLP) continues advancing, it offers opportunities to address various challenges that logbooks present. This work explores jointly testing a tailored Retrieval Augmented Generation (RAG) model for enhancing the usability of particle accelerator logbooks at institutes like DESY, BESSY, Fermilab, BNL, SLAC, LBNL, and CERN. The RAG model uses a corpus built on logbook contributions and aims to unlock insights from these logbooks by leveraging retrieval over facility datasets, including discussion about potential multimodal sources. Our goals are to increase the FAIR-ness (findability, accessibility, interoperability, and reusability) of logbooks by exploiting their information content to streamline everyday use, enable macro-analysis for root cause analysis, and facilitate problem-solving automation.
Paper: THPR37
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR37
About: Received: 16 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
THPR45
Research on ultra-high energy electron beams for FLASH radiation therapy at ELSA
3610
Ultra-high energy electrons (UHEE) are used to investigate their effect on tumor cells and healthy tissue in short pulses of microseconds at the electron accelerator facility ELSA. This may enable highly efficient treatment of deep-seated tumors due to the FLASH effect. In a preliminary setting electrons with an energy of 1.2 GeV are used to irradiate cell samples which are located inside a water volume, representing the human body. Irradiation occurs with dose rates of up to 10 MGy/s due to the short pulse lengths of 250 ns. The relative biological effectiveness (RBE) can be determined by assessing the cell survival of tissues under FLASH and conventional conditions. For a precise dose determination, dose measurements via radiochromic films are utilized and compared to simulations with Geant4, that reproduce the electromagnetic shower process.
Paper: THPR45
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR45
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPR47
Investigating X-ray detector systems using Monte Carlo techniques
3617
Digital Tomosynthesis (DT) is a 3D mode of x-ray imaging. Adaptix Ltd have developed a novel mobile DT device enabled by implementing an array of R-ray emission points and a flat-panel detector. This device gives access to human and animal 3D imaging, as well as to non-destructive material evaluation. DT is not as clinically popular as Computed Tomography (CT) or radiography, and flat-panel source DT even less so, thus creating scope to investigate the optimal flat-panel detector technology for this modality. Geant4, a Monte Carlo Particle Transport code, has been used to simulate the Adaptix Ltd system to do this. Parameters such as the material composition of the detectors, the exact detection method and the inclusion vs exclusion of a scintillation layer are tested in this simulation environment. This work aims to find the optimal flat-panel detector design by comparing different scintillator compositions and structures for this DT method. Therefore, the ideal detector that preserves the advantages of this low-cost, low-dose scanning approach is determined.
Paper: THPR47
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR47
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPR48
FLASHlab@PITZ beamline upgrade towards full functionality – status and plans
3621
At the Photo Injector Test facility at DESY in Zeuthen (PITZ), an R&D platform for electron FLASH cancer radiation therapy and radiation biology is being prepared: FLASHlab@PITZ. The design of the full beamline with optimized beam properties was finished; the setup is currently being finalized and the mechanical design and manufacturing is underway. The beamline runs in parallel to the SASE THz beamline at PITZ and is connected to it with a dogleg. Beam dynamics simulations were conducted to assure excellent beam quality at the experimental area. A fast kicker system will be installed which is capable of distributing electron bunches from a single bunch train freely over an area of 25mm x 25mm within one microsecond. When the full FLASHlab@PITZ beamline is ready in 2024, the accelerator will deliver 22 MeV electrons to generate dose rates from 0.01 Gy/s up to 10e+14 Gy/s to an experimental area, which can accommodate a variety of setups for irradiation studies. The flexible arrangement of the experimental area will make it possible for external users to collaborate with PITZ and conduct experiments with existing or newly designed irradiation setups.
Paper: THPR48
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR48
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
THPR49
Electronic brachytherapy replacement of iridium-192
3625
The replacement of radionuclides used for cancer therapy with accelerators offers several advantages for both patients and medical staff. These include the elimination of: unwanted dose, specialized storage and transportation, and isotope production/replacement. Several electronic brachytherapy devices exist, and typically utilize an x-ray tube around 50 keV. These have primarily been used for skin cancer, though intraoperative applications are becoming possible. For several types of cancer, Iridium-192 has been the only brachytherapy treatment option, due to its high dose rate and 380 keV average energy. An accelerator-based alternative to Ir-192 has been developed, comprised of a 9.4 GHz, 1 MeV compact brazeless accelerator, narrow drift tube, and target. The accelerator is supported and positioned through the use of a robotic arm, allowing for remote delivery of radiation for internal cancer treatment. Preliminary results including dose rate and profile and plans for complete system demonstration will be presented.
Paper: THPR49
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR49
About: Received: 21 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPR52
Medical irradiation studies at KIT accelerators
3635
Radiation therapy is an important oncological treatment method in which the tumor is irradiated with ionizing radiation. In recent years, the study of the beneficial effects of short intense radiation pulses (FLASH effect) or spatially fractionated radiation (MicroBeam/MiniBeam) have become an important research field. Systematic studies of this type often require research accelerators that are capable of generating the desired short intense pulses and, in general, possess a large and flexible parameter space for investigating a wide variety of irradiation methods. The KIT accelerators give access to complementary high-energy and time-resolved radiation sources. While the linac-based electron accelerator FLUTE (Ferninfrarot Linac- und Testexperiment) can generate ultrashort electron bunches, the electron storage ring KARA (Karlsruhe Research Accelerator) provides a source of pulsed X-rays. In this contribution, first dose measurements at FLUTE and KARA, as well as simulations using the Monte Carlo simulation program FLUKA are presented.
Paper: THPR52
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR52
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPR55
SAFEST project, a compact C-band RF linac for VHEE FLASH radiotherapy
3643
FLASH Therapy, an innovative cancer treatment, minimizes radiation damage to healthy tissue while maintaining the same efficacy in tumor cure as conventional radiotherapy. Successful integration of FLASH therapy into clinical practice, specifically for treating deep-seated tumors with electrons, relies on achieving Very High Electron Energy (VHEE) within the 50-150 MeV range. In collaboration with INFN, Sapienza University actively develops a compact C-band high-gradient VHEE FLASH linac called SAFEST. This paper presents the general layout and the main characteristics of the machine and the first prototype set for deployment at Sapienza University of Rome. This endeavor is a significant step towards the clinical implementation of FLASH Therapy.
Paper: THPR55
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR55
About: Received: 06 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPR61
Focusing of high-energy electron beam using silicon crystals for application in radiotherapy
3659
By using a high-energy electron beam (beam energy of several hundred MeV) strongly focused on the tumor lesion area, radiotherapy can be performed with a relatively simple beam generation and handling system while resulting in a suitable shape of the deposition energy curve in a tissue-like material. Quadrupole magnets are typically used for beam focusing, which makes the beam delivery system complex and challenging from an engineering point of view. In the Geant4 simulation toolkit, we performed a feasibility study of an alternative solution, in which focusing is achieved by using a bent silicon crystal with an appropriately shaped exit surface. However, the focusing strength is still not high enough. Research to find the optimal crystal shape to achieve the ideal focusing strength is ongoing. Such a crystal lens can be a very light object (mass in the order of grams), allowing for a much simpler beam delivery system for radiotherapy facilities.
Paper: THPR61
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR61
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPR64
Design of cyclotron-based in-vacuum material irradiation beamline at TINT
3671
A new cyclotron facility has been constructed at Thailand Institute of Nuclear Technology to provide proton beams with energy of 15-30 MeV for radioisotope production and material analysis. Due to requirements of particle induced X-ray emission (PIXE) and particle induced gamma-ray emission (PIGE) techniques that need a low-energy and low-intensity proton beam in range of 2-15 MeV and picoamperes as well as high detection sensitivity, the additional setup including an energy degrader, a collimator, a 30-degree separator magnet, and a slit, is employed for an in-vacuum irradiation beamline. In this work, we study the proton beam trajectory and beamline elements. The energy degrader made of aluminum has shown promising results in decreasing the beam energy while the energy spread of a secondary beam is significantly reduced by the following 30-degree separator magnet. Furthermore, the combination of the collimator and the slit lessens the beam current to proper values. To measure the proton beam current downstream, a copper Faraday cup will be used.
Paper: THPR64
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR64
About: Received: 12 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
THPR70
Development of a compact electron cyclotron resonance accelerator for industrial and security applications
3678
We describe the development of a novel accelerator, an electron Cyclotron Resonance Accelerator (eCRA) [1], to produce high power electron beams and X-ray beams for medical, research, sterilization, and national security applications. The several attractive features of eCRA include: a compact robust room-temperature single-cell RF cavity as the accelerating structure; continuous ampere-level high current output; and production of a self-rastering electron beam, thus eliminating the need for a separate beam scanner. Progress on the eCRA development, including numerical simulation, engineering design, and on-going experimental efforts will be reported here.
Paper: THPR70
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR70
About: Received: 24 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
THPR73
Status of ABC production line at Varex Imaging Corporation
3687
During past 7 years at Varex Imaging Corporation, we have created a pilot production line for Accelerator Beam Centerlines (ABC), replacing supply of Beam Centerlines (BCL) by Varian after the Component Division separated from Varian in 2017, becoming an independent public company. Our ABC production growth rate seems to double every year, and in last quarter of 2023 Fiscal Year, we delivered 35 ABCs, satisfying Industrial group full demand in such ABCs. In this 2024 Fiscal Year started on 1 October 2023, our goal is to deliver 12 units per month, but the stretch goal is to produce anywhere between 160 and 200 ABCs, which will include ABCs for 3, 6, and 9 MeV Linacs mostly for security screening, for Non-Destructive Testing (NDT), also a few units for our customers in radiation therapy business. We drive to complete the transition away from Varian to 100% in-house ABC production in 2025,
Paper: THPR73
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR73
About: Received: 07 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPR77
Progress on pulsed electron beams for radiation effects characterization of electronics
3694
Ultrafast high-energy pulsed electron beams can provide deep penetration and variable linear energy transfers for testing microelectronics for radiation-induced single-event effects. Early experiments at the UCLA PEGASUS beamline (3 MeV) with 1 ps electron bunches and a 50 $\mu$m spot size yielded charge collection transients that are compared with reference heavy ion data. Sub-micron focusing of the beam would allow for the electron bunch to better mimic ion tracks by saturating the charge collection in a small cross-sectional area while simultaneously providing high spatial resolution to allow for the targeted testing of microelectronic components. Using micron-scale collimators and strong lenses, current experiments are planned at UCLA to achieve smaller spot sizes in pursuit of stronger correlations with heavy-ion data.
Paper: THPR77
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR77
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
THPR79
Alternative gamma-ray source based on 2.2 MeV linear accelerator with field emission cathode
3698
High energy gamma-ray generators have the potential to be used in place of radioisotope sources, thus eliminating the security risk posed by radioisotopic sources. Euclid Techlabs design of nonradioisotopic gamma-ray source is based on ultra-compact linear accelerator with affordable magnetron RF power feeding. Wide aperture 15 cell X-band linac with embedded field emission cathode operates without expensive high voltage electron gun and bulky magnetic focusing system. 2.2 MeV output electron energy and 1 μA average accelerated beam current on composite target can provide gamma-ray spectrum similar to 2nd category Cs-137 radioisotope source.
Paper: THPR79
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR79
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
THPR83
Electrical fire safety assessment of the synchrotron accelerator experimental station in NSRRC
3704
The synchrotron facility and experimental station in the National Synchrotron Radiation Research Center (NSRRC) uses many electrical appliances, the improper use of which can cause fires, resulting in property damage and personal injury. Therefore, the usage of these electri-cal appliances must be assessed. This study conducted a comprehensive inspection and evaluation of the electrical appliances used in NSRRC, including extension cords and electrical connections; this was done to not only reduce the risk of fire but also emphasize the importance of electrical safety habits. We connected an extension cord reel in the NSRRC to a pump or a dehumidifier and used a thermal imaging cam-era to measure the temperature of the cord and these two appliances. We tested the extension cord reel when it was coiled up in the reel and straightened to determine which electrical appliances or extension cord states were prone to high temperatures and fires. The results showed that the extension cord was 18–20°C hotter when it was coiled than when it was straight. Therefore, we recommend that at least two-thirds of the length of the extension cord should be extended out of the reel when it is used.
Paper: THPR83
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR83
About: Received: 05 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
THPR85
Solid-state driven X-band linac for electron microscopy
3710
Current transmission electron microscopes (TEM) accelerate electrons to 200-300 keV using DC electron guns with a nanoamp of current and very low emittance. However at higher voltages these DC sources rapidly grow in size, oftentimes several meters tall for 1 MeV microscopes. Replacing these electron guns with a compact linac powered by solid-state sources could dramatically lower cost while maintaining beam quality, thereby increasing accessibility. Utilizing compact high shunt impedance X-band structures ensures that each RF cycle contains at most a few electrons, preserving beam coherence. CW operation of the RF linac is possible with distributed solid-state architectures* which power each cavity directly with solid-state amplifiers which can now provide up to 100W of power at X-band frequencies. We present a demonstrator design for a prototype low-cost CW RF linac for high-throughput electron diffraction producing 200 keV electrons with a standing-wave architecture where each cell is individually powered by a solid-state transistor. This design also provides an upgrade path for future compact MeV-scale sources on the order of 1 meter in size.
Paper: THPR85
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR85
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
THPS02
Upgrade of the SPARC_LAB low level radiofrequency system
3722
SPARC_LAB facility was born in 2004 as an R&D activity to develop a high brightness electron photo-injector dedicated to FEL experiments and exploration of advanced acceleration techniques. The electron source consists in a brazefree 1.6-cell S-band RF gun with a peak electric field of 120 MV/m and a metallic copper photocathode. The gun injects particles into two S-band sections, the initial section acting as an RF compressor using the velocity bunching technique, with built-in solenoid coils that enhance magnetic focusing and control emittance. A subsequent C-band acceleration section acts as a booster to achieve the desired kinetic energy. The Lazio Regional government recently funded the SABINA project for the consolidation of SPARC_LAB facility. The reference and the distribution systems and the Low Level radiofrequency (LLRF) system will also undergo a significant upgrade, involving the replacement of the original analogue S-band and digital C-band radiofrequency systems with commercial, temperature-stabilized, FPGA-controlled LLRF digital systems provided by Instrumentation Technologies in order to improve performance in terms of amplitude, phase resolution, and stability.
Paper: THPS02
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS02
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPS12
LCLS II DC magnet power supplies – an overview
3751
The Linac Coherent Light Source II (LCLS-II) at the SLAC National Accelerator Laboratory represents a groundbreaking advancement in the realm of Free Electron X-Ray Laser (XFEL) science. This 1.3 GHz continuous-wave superconducting RF LINAC is designed to generate 4 GeV electron bunches up to one MHz, propelling the capabilities of XFEL sources. Achieving a significant milestone, the LCLS-II successfully reached its 2K operating temperature with the first electrons in October 2022, culminating in the generation of the first x-rays in September 2023. This paper offers an overview of the diverse array of DC magnet power supplies (PSs) employed in LCLS-II, which can be categorized into two sections: warm and superconducting. The warm section comprises of two crucial types of PSs-intermediate and trim. Notably, these PSs are subjected to tight stability requirements as low as 20 ppm. The warm section has close to 600 PSs. In the superconducting section, an extra level of complexity is added by including a quench protection circuit to protect the magnets in case of a sudden loss of superconductivity. PSs in this section also have a stability requirement of 0.02 %. The superconducting section has 105 PSs. This paper also discusses the system design and performance of these PSs.
Paper: THPS12
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS12
About: Received: 30 Apr 2024 — Revised: 16 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
THPS21
Strain measurements of the Apple-X SABINA undulator with fiber Bragg grating
3777
The SABINA project will add a user facility to SPARC_LAB at INFN in Frascati (Rome). For the THz line, an electron beam is transported to the APPLE-X undulators to produce photon pulses in the ps range, with energy of tens of µJ, with linear or elliptical polarization. Each undulator has four magnetic arrays that can be moved radially simultaneously to set the operating gap. Two arrays can also move longitudinally for phase displacement. A structural analysis of this unique mechanical structure has been performed by the production company (KYMA S.p.a) to ensure good field quality and beam trajectory. To support those, a set of tests has been performed with FBG acting as strain sensors in Frascati. An FBG is a phase grating inscribed in the core of a single-mode fiber, whose Bragg-diffracted light propagates back along the fiber. Any deformation of the grating affects its pitch, which changes the diffracted Bragg wavelength thus giving information about the occurred deformation. Application of the technique at the state-of-the-art level allows to perform strain measurements with 1 µStrain resolution. Such analysis and results will be presented in this contribution.
Paper: THPS21
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS21
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPS32
Ultrafast high-voltage kicker system hardware for ion clearing gaps
3809
Ionization scattering of electron beams with residual gas molecules causes ion trapping in electron rings, both in a collider and electron cooling system. These trapped ions may cause emittance growth, tune shift, halo formation, and coherent coupled bunch instabilities. In order to clear the ions and prevent them from accumulating turn after turn, the gaps in a temporal structure of the beam are typically used. Typically, the gap in the bunch train has a length of a few percent of the ring circumference. In those regions, the extraction electrodes with high pulsed voltages are introduced. In this paper, we present the design consideration and initial test results of the high-voltage pulsed kicker hardware that includes vacuum device and pulsed voltage driver, capable of achieving over 3 kV of deflecting voltage amplitude, rise and fall times of less than 10 ns, 100 ns flat-top duration at 1.4 MHz repetition rate.
Paper: THPS32
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS32
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPS36
Research on key technologies for resonance injection of a compact X-ray light source
3816
To enhance the intensity of X-ray emission through bremsstrahlung radiation, a light source was designed based on an electron cyclotron and a compact electron storage ring. The compact structure and limited space posed challenges to the injection system. In this paper, we introduce the key component, the "perturbator," along with its matching pulse power supply. These were de-signed based on the half-integer resonance injection method. The injection of the electron beam via multiple perturbations enables multiple bombardments of the metal target, effectively increasing the brightness of the light source.
Paper: THPS36
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS36
About: Received: 15 May 2024 — Revised: 16 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
THPS56
Field characterization of axially and radially magnetized neodymium rings
3868
Permanent magnets are attractive options for nano focusing and $q$-magnification in MeV ultrafast electron diffraction (MeV-UED) due to their high field strengths and compact footprints. In this work, we present field characterization of axially and radially magnetized neodymium rings. Such rings can produce strong axisymmetric focusing and naturally fulfill the requirement of stigmatic imaging for post-sample optical systems. Field qualities of the rings and their application in MeV-UED are studied and presented.
Paper: THPS56
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS56
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPS57
Radiation dose simulations for Jefferson Lab’s permanent magnet resiliency LDRD study
3872
In late 2023, Thomas Jefferson National Accelerator Facility (Jefferson Lab) funded a Laboratory Directed Research and Development (LDRD) grant dedicated to investigating the impact of radiation on permanent magnet materials. This research initiative is specifically geared towards assessing materials slated for use in the CEBAF energy upgrade. The experimental approach involves strategically placing permanent magnet samples throughout the accelerator, exposing them to varying radiation doses. The simulation code BDSIM is used to first validate the data and then to simulate the effects on future higher energy passes to study the degradation effects on the permanent magnets. In this paper we present the progress of that work.
Paper: THPS57
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS57
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPS59
Design and instrumentation for permanent magnet samples exposed to a radiation environment
3879
This work is part of a larger program to study the effects of radiation on permanent magnets in an accelerator environment. In order to be sure that the permanent magnet samples are accurately placed, measured, and catalogued we have developed a system of sample racks, holders and measuring apparatuses. We have combined these holders and measurement racks with electronics to allow a single computer to catalogue the position and intensity of the magnet measurements. We outline the design of the apparatus, the collection software, and the methodology we will use to collect the data.
Paper: THPS59
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS59
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
THPS63
Relationship between anisotropy and cross rolling process for high purity niobium sheets
3893
The standard fabrication method for superconducting cavities is to press high RRR niobium sheets to form half cells, which are then joined by EBW (electron beam welding) to form cavities. If the anisotropy of the niobium sheet is too large, gaps will form when the half-cells are joined, so a sheet with low anisotropy is required. To reduce the anisotropy of the sheet, it is essential to apply cross-rolling during fabrication. In this experiment, three types of sheets were produced with different reduction rates during TSCR (Two Sep Cross Rolling). Then, the average anisotropy coefficient r ̅ and planar anisotropy Δr, the evaluation criteria of anisotropy, were compared to find a relationship between anisotropy and cross rolling condition. As a result, it was found that the Δr value was the smallest and the in-plane anisotropy was the smallest when the reduction ratio before and after cross rolling was the same. In addition, half cells of superconducting cavities were press formed using three types of niobium sheets, and the roundness of the equatorial part was measured. There was no difference among the three types.
Paper: THPS63
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS63
About: Received: 14 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPS66
Experimental design for validating the feasibility of in-situ plasma cleaning of normal conducting copper cavities
3901
To reduce the dark current and secondary electron multiplication in conventional conducting accelerator cavities, and to improve the quantum efficiency of copper photocathodes, thereby achieving higher beam quality and enhancing the acceleration gradient and operational stability of accelerators, Tsinghua University designed a 13.56 MHz internal coil-type capacitive discharge plasma experimental platform to validate the feasibility of in-situ plasma cleaning of conventional superconducting copper cavities. This paper mainly introduces the architecture of this experimental platform, including the structure of the experimental cavity and its accompanying gas system, microwave system, and monitoring system. This experiment also validates the oxidation and reduction capabilities of the active components in the plasma, particularly comparing the oxidation ability of excited oxygen atoms and oxygen ions and the reduction ability of excited hydrogen atoms and hydrogen ions. This experimental platform can be used for cleaning and reduction of small and simple copper structures and verifies the feasibility of In-situ plasma cleaning of conventional conducting copper cavities.
Paper: THPS66
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS66
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
FRXN1
Beam instrumentation for advancing accelerators
3916
Beam instrumentation is of critical importance for the operation and optimization of modern particle accelerators. With advancing accelerator technology and the increasing requirements for higher quality beams, it is an ever-present challenge that beam diagnostics must similarly progress. In this talk the instrumentation considered most impactful for the progress of 4th generation storage ring light sources is presented with reference to possible lessons learned, applicability to other accelerators and potential future directions.
Paper: FRXN1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-FRXN1
About: Received: 17 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
FRYD1
High-efficiency klystrons from a dream to a reality
3933
During last year a comprehensive R&D program on high-efficiency klystrons has been carried out in collaboration with industry. The first prototypes are being tested and experimental results are promising. The talk will describe the main results of this R&D focusing in the experimental ones.
Paper: FRYD1
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-FRYD1
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
FRYD2
Recent development and future direction of ring-type synchrotron light sources in Japan
3939
The 4th generation synchrotron light sources and energy recovery linacs progress greatly in Japan. The first 4th generation synchrotron light source in Asia, NanoTerasu, has been constructed through a public-private regional partnership, whereas soon SPring-8 is to be upgraded. The energy recovery linac, which features not only high brightness but also sustainability as the cERL, and its related technology such as DC gun injectors have been developed, also. The talk will present an overview and future direction of synchrotron radiation light sources in Japan, with a particular focus on recent advances in NanoTerasu.
Paper: FRYD2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-FRYD2
About: Received: 12 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024