| Paper | Title | Page |
|---|---|---|
| TUPLT001 | Beam Dynamics in 100 MeV S-Band Linac for CANDLE | 1129 |
|
||
| The report presents the results of the beam dynamics study in 100 MeV S-band linear accelerator foreseen as an injector for the CANDLE light source. An impact of the excited longitudinal and transverse wake fields on the particle energy spread and the beam transverse emittance are given. | ||
| TUPLT002 | The Small-gap Undulator Impedance Study | 1132 |
|
||
| The small gap undulator vacuum chamber resistive impedance model is developed. The vacuum chamber is considered as equal-radii tubes with the different wall materials (stainless steel "copper" stainless steel). The complete impedance was calculated as a sum of tubes and transitions impedances. The modal expansion method for transition impedance calculation is presented. | ||
| TUPLT003 | Transfer Matrices for the Coupled Space Charge Dominated Six-dimensional Particle Motion | 1135 |
|
||
| In this paper we present exact analytical solutions for the particle motion in the six-dimensional phase space taking into account the space charge forces of fully linear coupled beam. The transfer matrices for the typical elements of magnetic lattice, such as drifts, cavities, quadrupole and dipole magnets have been obtained. The symplectic transfer matrices are used to develop a tracking program for the coupled betatron and synchro-betatron motion that enables the simulation of the tilted beam effects in circular accelerators. | ||
| TUPLT006 | Simple Analytic Formulae for the Properties of Nonscaling FFAG Lattices | 1138 |
|
||
| A hallmark of the "non-scaling" FFAG lattices recently proposed for neutrino factories and muon colliders is that a wide range of momentum is compacted into a narrow radial band; dL/L is of order 10(-3) for dp/p of order unity. This property is associated with the use of F0D0 or FDF triplet lattices in which the F magnet provides a reverse bend. In this paper simple analytic formulae for key lattice properties, such as orbit displacement and path length as a function of momentum, are derived from thin-element models. These confirm the parabolic dependence of path-length on momentum observed with standard orbit codes, reveal the factors which should be adjusted to minimize its variation, and form a useful starting point for the thick-element design (for which analytic formulae are also presented). A key result is that optimized doublet, F0D0 and triplet cells of equal length and phase advance have equal path-length performance. Finally, in the context of a 10-20 GeV/c muon ring, the thin-element formulae are compared against lattice optical properties computed for thick-element systems; the discrepancies are small overall, and most discernible for the triplet lattices. | ||
| TUPLT007 | The CERN-SPL Chopper Concept and Final Layout | 1141 |
|
||
| The fast chopper for the CERN SPL (Superconducting Proton Linac) consists of a double meander structure with a beta (v/c) value of 8 % printed on an alumina substrate for the deflecting plates. Each chopper unit is 50 cm long and housed in a quadrupole magnet surrounding the vacuum chamber. The deflecting plates are operated simultaneously in a dual mode, namely traveling wave mode for frequencies above about 10 MHz and as quasi electro-static deflectors below. The deflecting structures are water-cooled to handle heating from beam losses as well as from the deflecting signal. A detailed mechanical layout is presented including the tri-axial feeding and termination technique as well as a discussion of the drive amplifier | ||
| TUPLT008 | A Retrofit Technique for Kicker Beam-coupling Impedance Reduction | 1144 |
|
||
| The reduction of the impedance of operational ferrite kicker structures may be desirable in order to avoid rebuilding such a device. Often resistively coated ceramic plates or tubes are installed for this purpose but at the expense of available aperture. Ceramic U-shaped profiles with a resistive coating fitting between the ellipse of the beam and the rectangular kicker aperture have been used to significantly reduce the impedance of the magnet, while having a limited effect on the available physical aperture Details of this method, constraints, measurements and simulation results as well as practical aspects are presented and discussed. | ||
| TUPLT009 | Trajectory Correction Studies for the CNGS Proton Beam Line | 1147 |
|
||
| The performance of the proposed trajectory correction scheme for the CNGS proton beam line was checked with an advanced simulation program. It was first investigated whether the scheme will be sufficient, and if some correctors or monitors could be suppressed in order to reduce the cost. The correction scheme was in particular tested for the case of faulty correctors or monitors. Possible critical scenarios were identified, which may not be visible in a purely statistical analysis. This part of the analysis was largely based on the experience with trajectory and orbit correction problems encountered in the SPS and LEP. The simulation of the trajectory correction procedure was done using recently developed software. | ||
| TUPLT010 | Aperture and Stability Studies for the CNGS Proton Beam Line | 1150 |
|
||
| The knowledge of the beam stability at the CNGS target is of great importance, both for the neutrino yield and for target rod resistance against non-symmetric beam impact. Therefore, simulating expected imperfections of the beam line elements and possible injection errors into the CNGS proton beam line, the beam spot stability at the target was investigated. Moreover, the mechanical aperture of the CNGS proton beam line was simulated and the results confirmed that the aperture is tight but sufficient. | ||
| TUPLT011 | The LHC Lead Ion Injector Chain | 1153 |
|
||
| A sizeable part of the LHC physics programme foresees heavy ion (lead-lead) collisions with a design luminosity of 1027 cm-2 s-1. This will be achieved after an upgrade of the ion injector chain comprising Linac3, LEIR, PS and SPS machines. Each LHC ring will be filled in ~10 minutes with ~600 bunches, each of 7 107 Pb ions. Central to the scheme is the Low Energy Ion Ring (LEIR), which transforms long pulses from Linac3 to high-brilliance bunches by means of 6D multi-turn injection and accumulation via electron cooling. Major limitations along the chain, including space charge, intra-beam scattering, vacuum issues, and emittance preservation are highlighted. The conversion from LEAR (Low Energy Antiproton Ring) to LEIR includes new magnets and power converters, high-current electron cooling, broad-band RF cavities, upgraded beam diagnostics, and UHV vacuum equipment relying on beam scrubbing to achieve a few 10-12 mbar. Major hardware changes in Linac3 (Electron Cyclotron Resonance source, repetition rate, energy ramping cavity), PS (new injection hardware, elaborate RF gymnastics, stripping insertion), and SPS (100 MHz system) are described. An early beam scenario, using fewer bunches but the same bunch intensity to deliver a lower luminosity, reduces the work required for LHC ion operation in spring 2008. | ||
| TUPLT012 | Adjusting the IP Beta-functions in RHIC. | 1156 |
|
||
| The beta- functions at the IP can be adjusted without perturbation of other optics functions via several approaches. In this paper we describe a scheme based on a vector knob, which assigns fixed values to the different tuning quadrupoles and scales them by a common multiplier. The values for the knob vector were calculated for a lattice without any errors using MADX. Previous studies for the LHC have shown that this approach can meet the design goals. A specific feature of the RHIC lattice is the nested power supply system. To cope with the resulting problems a detailed response matrix analysis has been carried out and different sets of knobs were calculated and compared. The knobs are tested at RHIC during the 2004 run and preliminary results maybe discussed. Simultaneously a new approach to measure the beam sizes of both colliding beams at the IP, based on the tune ability provided by the knobs, was developed and tested. | ||
| TUPLT013 | Calculating LHC Tuning Knobs using Various Methods | 1159 |
|
||
| By measuring and adjusting the beta-functions at the IP the luminosity is being optimized. In LEP this was done with the two closest doublet magnets. This approach is not applicable for the LHC due to the asymmetric lattice and common beam pipe through the triplet magnets. To control and change the beta-functions quadrupole groups situated on both sides further away from the IP have to be used where the two beams are already separated. The quadrupoles are excited in specific linear combinations, forming the so-called tuning knobs for the IP beta-functions. We compare the performance of such knobs calculated by different methods: (1) matching in MAD, (2) inversion of the re-sponse matrix and singular value decomposition inversion and conditioning and (3) conditioning the response matrix by multidimensional minimization using Hessian method. | ||
| TUPLT014 | Comparative Design Studies of a Super Buncher for the 72 MeV Injection Line of the PSI Main Cyclotron | 1162 |
|
||
| The envisaged current upgrade from 2 to 3 mA of the PSI 590-MeV main cyclotron requires an increase of the global accelerating voltage of the 50-MHz cavities which leads to a nearly unacceptable RF requirement for the 150-MHz flattop cavity. In order to preserve the longitudinal acceptance and transmission of the machine while relaxing the high demands on the flattop system, it is conceivable to install a buncher in the 72-MeV injection line. To this end, normal-conducting 150-MHz half-wave resonators and 500-MHz two-gap drift-tube cavities have been designed and optimised for minimum input power and peak surface fields. The dependence of the RF properties (Q0, shunt impedances and peak fields) with beam apertures and gap voltages compatible with beam-dynamics requirements are presented. | ||
| TUPLT015 | The Bunch Compressor System for SIS18 at GSI | 1165 |
|
||
| For bunch compression down to pulse durations of 50 ns, a dedicated rf system is under development for the SIS12/18 heavy ion synchrotron upgrade and will be described in this paper. Due to space restrictions in SIS12/18 the rf system consists of very short cavities which provide a very large voltage gradient (50 kV/m) at a very low frequency of approximately 800 kHz and rf final stages which provide a short rise time. The only possibilty to meet the requirements is the application of a cavity heavily inductively loaded by metallic alloy (MA) ring cores. This new rf system will be a prototype for the advanced acceleration and compression system needed in SIS100, which is the most important part for the proposed International Acceleration Facility at GSI. In order to gain experience with different MA ring core materials two of the four compressor cavities are loaded differently, which gives us an opportunity to learn the operational advantages of both materials. It is expected that the experimental results will support the final judgement for the future rf system in SIS100. | ||
| TUPLT016 | Improved Performance of the Heavy Ion Storage Ring ESR | 1168 |
|
||
| The heavy ion storage ring ESR at GSI allows experiments with stable and radioactive heavy ions over a large range of energies. The energy range available for operation with completely stripped ions has recently been extended to energies as low as 3 MeV/u. Even for bare uranium such low energies can be provided by deceleration of the ions which are stripped to high charge states in a foil at energies of 300-400 MeV/u. After injection the beam is cooled and decelerated in an inverse synchrotron mode interspersed with electron cooling at an intermediate energy. At the lowest energy of 3 MeV/u some hundreds of thousands ions could be electron cooled after deceleration. At energies of 10-20 MeV/u physics experiments with stored and slowly extracted beam have been performed with some million decelerated cooled ions. The cooling of radioactive ions by a combination of stochastic pre-cooling and final electron cooling has been demonstrated. The hot fragment beam, which was injected at an energy of 400 MeV/u, was cooled in about 6 s to a quality useful for precision experiments. | ||
| TUPLT017 | Achievements of the High Current Beam Performance of the GSI Unilac | 1171 |
|
||
| The present GSI-accelerator complex is foreseen to serve for the future synchrotron SIS100 as an injector for up to 1012 U28+ particles/sec. The High Current Injector of the Unilac was successfully commissioned five years ago. An increase of more than two orders of magnitude in particle number for the heaviest elements in the SIS had to be gained. Since that time many different ion species were accelerated in routine operation. In 2001 a physics experiment used 2×109 Uranium ions per spill. In order to meet this request the MEVVA ion source provided for the first time in routine operation a high intense Uranium beam. The main purpose for the machine development program during the last two years was the enhancement of the intensity for Uranium beams. Different hardware measures and a huge investigation program in all Unilac-sections resulted in an increase of the uranium intensity by a factor of 7. The paper will focus on the measurements of beam quality, as beam emittance and bunch structure for Megawatt-Uranium beams. Additionally the proposed medium- and long-term hardware measures will be described, which should gain in the required uranium intensity to fill the SIS up to the space charge limit. | ||
| TUPLT018 | Layout of the Storage Ring Complex of the International Accelerator Facility for Research with Ions and Antiprotons at GSI | 1174 |
|
||
| The storage ring complex of the new international accelerator facility consists of three different rings: the Collector Ring CR, the accumulator/decelerator ring RESR and the New Experimental Storage Ring NESR. The CR will serve for fast stochastic precooling of antiproton and rare isotope (RI) beams. Cooling time constants of about 100 ms for RI beams are envisaged. For experiments with RI beams the RESR serves as a decelerator ring. Precooled RI beams will be injected at 740 MeV/u and then decelerated to variable energies down to 100 MeV/u within about 1 s. The NESR will be the main instrument for nuclear and atomic physics. Besides experiments using an internal gas target, the NESR offers the possibility to collide circulating bunches of ions with electron bunches counter-propagating in a small 500 MeV electron storage ring. The physics program with antiprotons requires the accumulation of high intensity antiproton beams. The accumulation of 7×1010 antiprotons at 3 GeV per hour is foreseen. This will be accomplished by operating the RESR as an accumulator ring equipped with a stochastic cooling system. The NESR could then be used to decelerate antiprotons to 30 MeV. | ||
| TUPLT019 | Nonlinear Effects Studies for a Large Acceptance Collector Ring | 1177 |
|
||
| A large acceptance collector ring (CR) is designed for fast cooling of rare isotope and antiproton beams, which will be used for nuclear physics experiments in the frame of the new international accelerator facility recently proposed at GSI. This contribution describes the linear and non-linear optimisation used to derive a lattice solution with good dynamic behaviour simultaneously meeting the demands for very fast stochastic cooling for two optical modes (for rare isotope and antiproton beams). Effects due to non-linear field contributions of the magnet field in dipoles and quadrupoles are very critical in this ring. Using a single particle dynamics approach, the major magnetic non-linearities of the CR are studied. We discuss the particle dynamics of the dipole and quadrupole fringe fields and the their influence on the dynamic aperture and on the tune. Additionally, the CR will be operated at the transition energy (isochronous mode) for time of flight (TOF) mass spectrometery of short-lived radioactive ions. For this mode a specific correction scheme is required to reach a high degree of isochronism over a large acceptance. | ||
| TUPLT020 | High Intensity Uranium Operation in SIS18 | 1180 |
|
||
| For the present experiment program and the planned international accelerator facility at GSI, the space charge limit of SIS18 for highly(4x1010) and intermediate (2.7x1011) charged uranium ions shall be reached within the next four years. Furthermore, measures to increase the repetition- and ramp rate up to 4 Hz with 10 T/s have been progressed. The present state of intensities per cycle and the limitations will be described. In connection with the planned enhancement of heavy ion intensities, protection, interlock and diagnostic systems, especially for the injection- and extraction devices have been prepared. Special attention is drawn on the insights which were achieved with respect to the operation at dynamic vacuum conditions. Results of R&D work with the goal to increase the intensity threshold and to improve the beam life time will be summarized. Furthermore, the specific upgrade program and schedule for the SIS18 booster mode will be presented. | ||
| TUPLT021 | Heavy Ion Beam Transport in Plasma Channels | 1183 |
|
||
| The transport of heavy ion beams in high current discharge channels is a promising option for the final beam transport in a heavy ion fusion reactor. The channel provides space-charge neutralization and an azimuthal magnetic field of several tesla, thereby allowing for transporting high current ion beams. The possibility to heat the hohlraum target with only two ion beams simplifies the reactor design significantly. Therefore channel transport is studied as part of the US fusion reactor study as an alternative to neutralized ballistic focusing. We have created 1 m long discharge channels and studied the channel development and stability. In addition, we have carried out proof-of-principle transport experiments using the UNILAC facility at the Gesellschaft für Schwerionenforschung. The experiments demonstrate the feasibility of plasma channel transport. Our transport experiments with low current beams are supplemented by simulations for high current beams. These simulations show the possibility of transporting particle currents of up to 60 kA. | ||
| TUPLT022 | Beam Dynamics Simulations at the S-DALINAC for the Optimal Position of Beam Energy Monitors | 1186 |
|
||
| The S-DALINAC is a 130 MeV superconducting recirculating electron accelerator serving several nuclear and radiation physics experiments as well as driving an infrared free-electron laser. For the experiments an energy stability of 1·10-4 should be reached. Therefore noninvasive beam position monitors will be used to measure the beam energy. For the measurement the different flight time of the electrons to the ideal particle are compared, that means in the simulations the longitudinal dispersion of the beam transport system is used for the energy detection. The results of the simulations show that it is possible to detect an energy difference of 1·10-4 with this method. The results are also proven by measurements. | ||
| TUPLT023 | A New Ion Beam Beam Facility for Slow Highly Charged Ions | 1189 |
|
||
|
A new ion beam facility for slow highly charged ions is presented. It will provide slow highly charged ions from an Electron Cyclotron Resonance (ECR) ion source as well as very highly charged ions at lower ion currents from an Electron Beam Ion Trap (EBIT). As ECR ion source a SUPERNANOGAN source* is applied. The Dresden EBIT**, a room-temperature EBIT, is used to produce comparatively low currents of very highly charged ions. This very compact and long-term stable device is producing highly charged ions at ultimate low costs. The Dresden EBIT working with electron energies up to 15 keV at electron currents up to 50 mA is able to produce bare nuclei up to nickel as Fe26+ or Ni28+, helium-like ions for medium Z such as Ge30+ or Kr34+ and neon-like ions for elements of the high-Z region such as Xe44+ or Ir67+. The ion currents extracted from the Dresden EBIT are typically in the range of some nA per pulse. With the new ion beam facility outstanding possibilities for a wide range of investigations are opened up in areas such as surface analysis, materials science and nanotechnology as well as for basic research in different fields as for instance in atomic and solid state physics.
*The Pantechnik Catalogue, August 2001 Edition, Caen 2001, France **V.P.Ovsyannikov, G.Zschornack; Review of Scientific Instruments, 70 (1999) 2646 |
||
| TUPLT024 | A Comparison of High Current Ion Beam Matching from an Ion Source to a RFQ by Electrostatic and by Magnetic Lenses | 1192 |
|
||
| In order to improve the ?direct? injection scheme of the Riken Nd-YAK-laser driven ion source into a RFQ rf-accelerator, several basic methods have been investigated and compared, in order to transform the initially divergent ion beam into a convergent one, needed for matching the high current (100 mA C6+) ion beam at an energy of 100 keV to a RFQ. From the point of power supplies and break down characteristics, the simplest solution is a decelerating electrostatic lens, with the decelerating electrode operated on ion source potential. Due to the strong divergence of the ions beam after acceleration, this lens will be filled to an aperture, which causes strong aberrations. Therefore, we also investigated to use an accelerating potential on the lens electrode. This reduces significantly the filling of the lens and the emittance growth is only a factor of 3, as compared to the decelerating lens with a factor of 30! Finally we have been looking also into a magnetic matching system, which can match the ion beam to the RFQ with virtually no emittance growth. | ||
| TUPLT025 | Matching of a C6+ Ion Beam from a Laser Ion Source to a RFQ | 1195 |
|
||
| A laser ion source, driven by a Nd-YAG laser can provide more than 100 mA of C6+ ions for a duration of about 1 μs, which is well matching the task of single-turn injection into synchrotrons for hadron tumor therapy with light ions. The ?direct? injection scheme has been improved by providing a design, which reduces the surface field strength to less than 30 kV/cm on all critical parts on relative negative potential. The new design keeps the advantage of divergent ion emission and acceleration, which seems to be the only way to keep the surface fields in limits, but includes a decelerating electrostatic lens on birth potential of the ions to refocus the emerging ion beam to the RFQ entrance. The whole design is very compact and allows for electrostatic steering between the ion source and the RFQ. | ||
| TUPLT026 | High Current Ion Beams at Frankfurt University | 1198 |
|
||
| A new building for the physics faculty at the Goethe-University in Frankfurt is under construction including an experimental hall. The Institute of Applied Physics IAP has started development of a high current ion beam facility consisting of a high voltage terminal(150 kV,I_beam < 300 mA,H-,p,Bi+), a 10 MV linear rf accelerator and a high current storage ring for 150 keV beams. The 150 kV terminal equipment is already ordered while the subsequent units are in the design stage. The storage ring will use a stellarator-like magnetic configuration to allow for a high degree of space charge compensation by electrons. The facility will allow high current beam investigations as well as experiments in fields of plasma, nuclear and atomic physics. | ||
| TUPLT027 | Status of the HITRAP Decelerator Linac at GSI | 1201 |
|
||
| Within the European Network HITRAP (heavy Ion trap) trapped and cooled higly charged ions up to U92+ will become avilable for a variety of attractive experiments in atomic physics. Heavy ions are produced, accelerated and stripped in the GSI accelerator complex and are stored in the ESR down to 4 MeV/u. To be captured in HITRAP, ions have to be decelerated to energies below 6 keV/u. The decelerator proposed to achieve these energies is a combination of an IH Drift tube cavity operating in the H11(0) mode and a RFQ. The operating frequency is 108.408MHz . The A/q range of the linac is up to 3. A very efficient deceleration by up to 11 MV along the 2.7 m long IH cavity with a rf power of 200kw is achieved by applying the KONUS beam dynamics. The deceleration from 500 A.keV down 6A.keV is provided by a 1.8 m long 4-rod RFQ.The beam dynamics as well as the cavity design of that linac will be described.The decelerator linac will be installed in the reinjection beam line and is being developed in collaboration between GSI and the Frankfurt University . | ||
| TUPLT028 | Development of Finger Drift Tube Linacs | 1204 |
|
||
| At higher particle energies the efficiency of RFQs decreases and DTL structures in combination with magnetic quadrupoles are used. One approach at IAP is the combination of RFQ and DTL. To compensate the defocusing effects of a DTL structure, the accelerating gaps of a spiral loaded cavity were equiped with small focusing fingers. These fingers arranged in a quadrupole symmetry provide an additional focusing field component. The beam dynamics of such a cavity has been studied with PARMTEQ. Simulations of the rf properties have been done using microwave studio. A prototype of a spiral loaded cavity with finger drift tubes has been built and low power measurement were made. Results of the calculations as well as low level and bead pertubation measurements are presented in this contribution. | ||
| TUPLT029 | Status of the Superconducting D+-CH-DTL Design for IFMIF | 1207 |
|
||
| Within the IFMIF project (International Fusion Materials Irradiation Facility) a high current D+-linac operated in cw mode has to be developed. The acceleration of a 125 mA D+-beam from 0.1 MeV up to 40 MeV must be performed at an extremely low loss rate (0.1-0.2 microA/m). One optional layout of the acceleration facility consists of a high current ion source, low energy beam transport (LEBT), Radio-Frequency-Quadrupol (RFQ) followed by a superconducting H-type DTL. The matching of the beam between subsequent linac sections has to be carefully optimized to avoid an activation of the structures. Actual beam dynamics simulations for such a linac design including parameter errors of components are reported. Consequences for the LEBT- and RFQ-section are discussed. | ||
| TUPLT030 | Numerical Simulations for the Frankfurt Funneling Experiment | 1210 |
|
||
| High beam currents are necessary for heavy ion driven fusion (HIF) or XADS. To achieve these high beam currents several ion beams are combined at low energies to one beam using the funneling technique. In each stage a r.f. funneling deflector bunches two accelerated beam lines to a common beam axis. The Frankfurt Funneling Experiment is a scaled model of the first stage of a HIF driver consisting of a Two-Beam RFQ accelerator and a funneling deflector. Our two different deflectors have to be enhanced to reduce particle losses during the funneling process. This is done with our new developed 3D simulation software DEFGEN and DEFTRA. DEFGEN generates the structure matrix and the potential distribution matrix with a Laplace 3D-solver. DEFTRA simulates ion beam bunches through the r.f. deflector. The results of the simulations of the two existing deflectors and proposals of new deflector structures will be presented. | ||
| TUPLT032 | The Frankfurt Funneling Experiment | 1213 |
|
||
| The Frankfurt Funneling Experiment is a scaled model of the first funneling stage of a HIF driver to gather experiences in the funneling technique. It is a procedure to multiply beam currents at low energies in several stages. In each stage two beam lines are combined to a common beam line. The funneling technique is required for new proposed high current accelerator facilities like HIDIF. The main goal is to prevent emittance growth during the funneling process. Our experiment consists of two ion sources, a Two-Beam RFQ accelerator, two different funneling deflectors and a beam diagnostic equipment system. We have demonstrated the principle of funneling with both deflector types. But the measurements have shown a bad matching of the RFQ to the funneling deflector. Now with our new RFQ electrode design we achieve a special three dimensional matching to the deflector. The new results of our measurements and simulations will be presented. | ||
| TUPLT033 | RF Design of the MAFF IH-RFQ Power Resonator | 1216 |
|
||
| The low energy part of the LINAC of the MAFF facility will be an IH-RFQ cavity with 101.28 MHz resonance frequency. The RF design of the cavity has been completed, including design calculations and model measurements. The RFQ is designed to deliver ions of A/q = 6.5 up to 300 keV/u to be injected into the following LINAC. The structure chosen was an IH type of resonator since it was demontrated to have a better shunt impedance. The required voltage between the electrodes is 70kV and the operation mode is pulsed with a duty cycle of 10%. The structure will be made out from bulk copper in order to improve the shunt impedance and hence to allow not direct cooling on the electrodes. The optimizazion of the several parameters of the structure, and the technique for tuning the voltage distribution are presented in this paper. Measurements with a short model will be shown as well. | ||
| TUPLT034 | Beam Dynamics Studies for the Low Energy Section at MAFF | 1219 |
|
||
| For the LINAC of the Munich accelerator for fission fragments (MAFF) a new scheme for the low energy section has been proposed in order to fulfill new experimental requirements, such as time spacing between bunches and low longitudinal emittance. The proposed solution consists in a combination of an external multi-harmonic buncher with a "traditional" RFQ with a shaper and an adiabatic bunching section included where the employment of the external buncher is upon request from the experiment. The matching section downstream the RFQ has been re-designed in order to allow room for the installation of a beam cleaning section and to a proper injection into the following DTL. Details about the optics and beam dynamics studies of the low energy section are presented in this paper. | ||
| TUPLT035 | Online Calculation of the Beam Trajectory in the HERA Interaction Regions | 1222 |
|
||
| During the HERA luminosity upgrade the new super conducting mini beta quadrupoles have been placed inside the experiments for final focussing and separation of the lepton and proton beams. The synchrotron radiation of up to 12 kW produced in these magnets passes through the detector and is absorbed behind the experiments. In order to avoid background events from synchrotron radiation it is a mandatory to adjust precisely the beam trajectory before and inside the detector. A procedure has been developed to calculate the trajectory in the interaction regions. With a beam-based alignment the offsets of the beam with respect to the quadrupoles is measured. From this measurement the offsets of the quadrupoles and of the beam position monitors are fitted. With the knowledge of these offsets the trajectory of the beam is calculated with high precision. The display of the trajectory is online available as an operational tool for beam steering and background optimization. | ||
| TUPLT036 | Optimization of Low Emittance Lattices for PETRA III | 1225 |
|
||
| The reconstruction of the existing 2.3 km long storage ring PETRA II into a 3rd generation synchrotron light source (PETRA III) calls for an horizontal emittance of 1 nm rad. In addition the on- and off-momentum dynamic acceptance should be large to ensure sufficient injection efficiency and beam lifetime. We present three different types of lattices for the arcs of PETRA: a so-called TME lattice and a FODO lattice which both are newly designed to reach the specified emittance and the present FODO lattice with damping wigglers. The different lattice types have been compared through tracking calculations, including wiggler nonlinearities. Only the relaxed FODO lattice with damping wigglers meets the acceptance goals. | ||
| TUPLT037 | Dispersion Correction in HERA | 1228 |
|
||
| The electron-proton collider HERA at the DESY laboratory in Hamburg has been in operation since 1991. After the luminosity upgrade of HERA in 2001 the control of the horizontal and vertical dispersion function of the positron beam became more important than before. Deviations from the design dispersion in the horizontal plane can change the emittance of the electron beam significantly thus leading to a reduction of the luminosity. For optimizing the polarization of the electron beam the reduction of vertical orbit and dispersion deviations is important. In this paper the combined dispersion and orbit correction in HERA is described and first results are reported. | ||
| TUPLT038 | Closed Orbit Correction and Orbit Stabilisation Scheme for the 6 GEV Synchrotron Light Source PETRA III | 1231 |
|
||
| PETRA III is a 6 GeV synchrotron light source being reconstructed out of the existing storage ring PETRA II. It will have a horizontal beam emittance of 1nm.rad and a 1% emittance ratio. Since the vertical beam sizes are ~5?10 micron in the low gap undulators sections the beam position stability requirement in the vertical plane is between 0.5 and 1 micron whereas the stability requirement in the horizontal plane is more relaxed. In this paper determination of golden orbit in the presence of magnetic field errors and magnet misalignments and correction of vertical spurious dispersion is discussed. A scheme of slow and fast orbit correction using the SVD algorithm has been developed. The distribution of monitors and the location of slow and fast correctors are reported. Estimations of the parameters of the fast orbit feedback have been derived from present measurements on PETRA II. | ||
| TUPLT039 | An Electrostatic Quadrupole Doublet with an Integrated Steerer | 1234 |
|
||
| Electrostatic storage rings have proven to be a valuable tool for atomic and molecular physics Due to the mass independence of the fields in the bending and focusing elements, different kinds of ions with the same charge/energy ratio from light protons to very heavy biomolecules, can be stored with the same field setup. The transverse dimensions of the circulating beam are controlled by electrostatic quadrupole doublets or triplets. It is essential that the fields in these lenses can be adjusted independently one from another to allow an exact control of the stored ions. In this paper, first an overview of the principle of electrostatic lenses is given. After a short discussion of fringe field effects, the results of field calculations are presented and the final layout of an electrostatic quadrupole doublet with an integrated steerer as it will be used in future electrostatic storage rings in Frankfurt and Heidelberg is discussed. | ||
| TUPLT040 | CSR - a Cryogenic Storage Ring at MPI-K | 1237 |
|
||
| A small cryogenic storage ring is planned to be developed at MPI-K, Heidelberg. The energy in the machine will be variable from 300 keV > down to 20 keV. Electron cooling will be applied to produce a high quality ion beam. The ring shall accommodate slow, vibrationally and rotationally cooled molecular ions and highly charged ions from the EBIT ion source. Moreover, it will serve as a test facility for the low-energy antiproton ring planned within the FLAIR collaboration to be installed at the future GSI facility. A number of technological challenges have to be handled: Especially highly charged ions require a vacuum in the order below 10-13 mbar to achieve reasonable lifetimes. Therefore - and for enabling experiments with rotationally cold molecules - the complete machine will be cooled down to below 10 K. Moreover, experiments with reaction microscopes to determine the full kinematics of ion- (antiproton-) atom or molecule collisions require a bunched operation with a bunch length below 2 ns. The optical elements of the machine and the lattice functions are given and first ideas about the vacuum chamber design are described in this paper. | ||
| TUPLT041 | Ultra-low Energy Antiprotons at FLAIR | 1240 |
|
||
| The Future Accelerator Facility for Beams of Ions and Antiprotons at Darmstadt will produce the highest flux of antiprotons in the world. So far it is foreseen to accelerate the antiprotons to high energies (3-15 GeV) for meson spectroscopy and other nuclear and particle physics experiments in the HESR (High Energy Storage Ring). Within the planned complex of storage rings, it is possible to decelerate the antiprotons to about 30 MeV kinetic energy, opening up the possibility to create low energy antiprotons. In the proposed FLAIR facility the antiprotons shall be slowed down in a last step from 300 keV to 20 keV in an electrostatic storage ring (USR) for various in-ring experiments as well as for their efficient injection into traps. In this energy range - especially if one thinks about realizing a real multi-purpose facility with not only antiprotons, but also various highly-charged radioactive ions to be stored and investigated - electrostatic storage rings have clear advantages compared to their magnetic counterparts. In case one envisions to even approach the eV range, electrostatic machines are the only possible choice. This contribution presents the layout and design parameters of the USR. | ||
| TUPLT042 | Ring of FIRE | 1243 |
|
||
| A small electrostatic storage ring is the central machine of the Frankfurt Ion stoRage Experiments which will be build up at the new Stern-Gerlach-Center of Frankfurt university. With ion energies up to 50 keV it will allow new methods to analyze complex many-particle systems from atoms to very large bio molecules. The high luminosity of the beam allows measurements with many orders of magnitude better resolution compared to traditional measurements. It will be combined with existing experiments, like the reaction microscope COLTRIMS and the ECR ion source. In comparison to earlier designs, the ring lattice was modified in many details: Problems in earlier designs were related with e.g. the detection of light particles and highly charged ions with different charge states. Therefore, the deflectors were redesigned completely, allowing a more flexible positioning of the diagnostics. In this contribution the final design of the storage ring is presented and the layout of all elements given. First results from vacuum measurements in the recently assembled quarter ring section are summarized. | ||
| TUPLT043 | Status of the Cooler Synchrotron COSY-Juelich | 1246 |
|
||
| The cooler synchrotron COSY accelerates and stores unpolarized and polarized protons and deuterons in the momentum range between 300 MeV/c to 3.65 GeV/c. To provide high quality beams, an Electron Cooler at injection and a Stochastic Cooling System from 1.5 GeV/c up to maximum momentum are available. Vertically polarized proton beams with a polarization of more than 0.80 are delivered to internal and external experimental areas at different momenta. Externally, the maximum momentum is up to date restricted to approximately 3.4 GeV/c by the extraction elements installed in COSY. In 2003 deuteron beams with different combinations of vector and tensor polarization were made available for internal and external experiments. An rf dipole was installed, which is used to induce artificial depolarizing resonances. It can be used for an accurate determination of the momentum of the stored beams. The status of the cooler synchrotron COSY is presented and future plans are discussed. | ||
| TUPLT044 | Delta-T Procedure for Superconducting Linear Accelerator | 1249 |
|
||
| Development of the tune-up procedure for a linear accelerator is the next important stage after the design is complete. Conventional delta-T procedure developed for tuning of a normal-conducting linear accelerator by Crandall allows setting up of accelerating field amplitude and phase in cavity with known phase velocity. However, application of the delta-T procedure to a superconducting linac meets some difficulties. In particular, the synchronous phase velocity in superconducting linac is determined by RF phase shift between cavities, but not by geometrical size of accelerating cells as in normal conducting linac. Additionally, in superconducting linac the smaller phase advance leads to an insensibility of particles at the cavity exit to the variation of the electric field inside the cavity. In the paper we consider the modified delta-T procedure adjusted for superconducting linac. Numerical simulations prove that by proposed technique both tasks of preservation of necessary stable region motion and providing the beam with required final energy can be successfully solved. | ||
| TUPLT045 | Separatrix Formalism Applied to Linacs Accelerating Particles with Different Charge to Mass Ratio | 1252 |
|
||
| We have developed separatrix formalism for superconducting linear accelerators. This method allows optimizing the quasi-synchronous velocity behavior along a linac. It gives a great advantage in acceleration of particles with different charge to mass ratio. In the article design optimization of structure supposed to accelerate different particles is presented. As an example for numerical simulation superconducting injector COSY is taken. | ||
| TUPLT046 | Luminosity Considerations for Internal and External Experiments at COSY | 1255 |
|
||
| The future physics program at the Cooler-Synchrotron COSY in Jülich requires intense beams to provide high luminosities up to 1032cm-2s-1 for internal and external experiments. In 2003 the number of unpolarized protons could significantly be increased up to the theoretical space charge limit of COSY. This was achieved by careful study and adjustment of all subsystems in the accelerator chain of COSY. The intensities for polarized proton beams are at best an order of magnitude lower compared to one for unpolarized beams, depending on the beam current provided the injector cyclotron. Still there is some potential for further enhancement of polarized beam intensities. In this paper, luminosity considerations for polarized and unpolarized beams at COSY are presented taking into account different machine cycles and operation modes for internal and external experimental set-ups. | ||
| TUPLT047 | First Results of Pulsed Superconducting Half-wave Resonators | 1258 |
|
||
| A pulsed linac for the cooler synchrotron COSY was projected based on superconductive half-wave resonators (HWRs). The concept of single phased resonators is a great challenge related to the requirement of accelerating protons and deuterons up to a similar energy. A cryomodule, which houses four cavities was designed in Cooperation with FZJ-ZAT, taking into account the restricted space and the special requirements of a linear accelerator. Two prototypes of the 160MHz Half-Wave Resonators (HWRs) were built at different companies. The fabrication differs slightly concerning the top and bottom parts of the cavity as well as the welding of the inner and outer conductor. First results of warm and cold measurements will be presented. The behaviour of the adjustable 4kW main coupler as well as the mechanical tuner can be tested together with the HWR in a new vertical test-cryostat. | ||
| TUPLT049 | Triple-spoke Cavities in FZJ | 1261 |
|
||
| We report the situation with superconducting triple-spoke cavity activities at the research center FZJ in Juelich. The Nb prototype of the 700 MHz, beta=0.2 cavity is already in fabrication and should be tested this year. This work has been initiated for the European Spallation Source project. In the frames of the new European project of High Intensity Pulsed Proton Injector the 352 MHz, beta=0.48 cavity is under developments. This cavity should be designed, built and tested in the Lab within next few years. | ||
| TUPLT050 | Lattice for CELLS | 1264 |
|
||
| The CELLS is an approved project to build a national synchrotron light source in Spain. The main goals of the project are to provide a medium energy machine (3 GeV) with low emittance and top up operation, a circumference of ~280 m and at least 12 straight sections available for experiments. At present, two lattices are being considered. The first one is based in QBA optics and provides and emittance of 5 nm-rad, using existing technologies. The second one is a TBA one, with an emittance of 2 nm, where physical aperture are reduced by at least a factor 2 and gradients in the bending magnets are up to 10 T/m. We present the selected lattice, and review the main beam dynamics (energy acceptance, errors) issues. | ||
| TUPLT051 | Beam Optical Design of a Multi Charge Ion Recirculator for Charge Breeders | 1267 |
|
||
| Ions of high charge states as required for both stable and radioactive beams in order to optimally profit from the existing accelerating voltage can be produced by means of a charge breeder. However, the energy increase obtained is accompanied by an intensity decrease due to the low efficiency of the charge breeding process. With respect to the production of radioactive beams an enhancement of the breeding efficiency would be most desirable to avoid a high power primary beam as yet inevitable to counteract the loss in intensity. For this purpose the beam optics of an ion recirculation capable to separate the desired charge state and to reinject the remaining charge spectrum has been designed. The ions extracted from both sides of the charge breeder are focused by electrostatic quadrupole doublets and bent by two 180° dipole magnets. After one revolution the optics realises horizontally a (1:1) and vertically a (1:-1) point-to-point image independent from the charge state of the ions. The second order geometric aberrations as well as most of the chromatic aberrations vanish. | ||
| TUPLT052 | GANIL Status Report | 1270 |
|
||
| The GANIL facility (Caen, France) is dedicated to the acceleration of heavy ion beams for nuclear physics, atomic physics, radiobiology and material irradiation. The production of radioactive ion beams for nuclear physics studies represents the main part of the activity. The in-flight fragmentation method was already used, since 1994, with the SISSI device. Since September 2001, SPIRAL, the Radioactive Ion Beam Facility at GANIL, delivers radioactive species produced by the ISOL method. The heavy ion beams of GANIL are sent onto a target and source assembly, and the radioactive beams are accelerated up to a maximum energy of 25 MeV/u by the cyclotron CIME. The operation and the running statistics of GANIL-SPIRAL are presented, with particular attention to the first SPIRAL beams. Few results about the cyclotron CIME, as the mass selection and tuning principle are summarized. The recent developments for increasing stable beams intensities, up to a factor 13 for argon, for use with SPIRAL, SISSI, or the LISE spectrometer, are presented. Considering the future of GANIL, SPIRAL II projects aims to produce high intensity secondary beams, by fission induced with a 5 mA deuteron beam in an uranium target. | ||
| TUPLT053 | Recent Evolutions in the Design of the French High Intensity Proton Injector (IPHI) | 1273 |
|
||
| In 1997, the two French National Research Agencies (CEA and CNRS) decided to collaborate in order to study and construct a prototype of the low energy part of a High Power Proton Accelerator (HPPA). The main objective of this project (the IPHI project), is to allow the French team to master the complex technologies used and the control concepts of the HPPAs. Recently, a collaboration agreement was signed with the CERN and led to some evolutions in the design and in the schedule. The IPHI design current was maintained at 100 mA in Continuous Wave mode. This choice should allow to produce a high reliability beam at reduced intensity (typically 30 mA) tending to fulfill the Accelerator Driven System requirements. The output energy of the Radio Frequency Quadrupole (RFQ), originally set to 5 MeV, was reduced to 3 MeV, allowing then the adjunction and the test in pulsed mode of a chopper line developed by the CERN for the Superconducting Proton Linac (SPL). In a final step, the IPHI RFQ and the chopper line should become parts of the SPL injector. In this paper, the IPHI project evolutions are reported as well as the construction and operation schedule. | ||
| TUPLT054 | Design of the Low-beta, Quarter-wave Resonator and its Cryomodule for the SPIRAL 2 Project | 1276 |
|
||
| The SPIRAL 2 project, to be built in GANIL, consists of a 40 MeV linear accelerator for 5 mA of deuterons and a target-source complex for the production of exotic isotopes. The accelerator is also optimised to accelerate q/A = 1/3 ion up to 14.4 MeV/u. The three stages of the linac are a RFQ (up to 0.75 MeV/A), a low beta (0.007) and a high beta (0.12) sections consisting of quarter-wave, 88 MHz superconducting resonators. This paper focuses on the low beta cavity and its cryomodule. The cavity nominal accelerating gradient is at least 6.5 MV/m in operation conditions. RF properties of the cavities are dealt with, as well as the mechanical ones: helium pressure effects, tunability, vibrations. The cryomodule is designed so as to save longitudinal space and therefore is partly assembled in clean room. | ||
| TUPLT056 | ECRIS Development for the SPIRAL II Project | 1279 |
|
||
| The SSI/LPSC laboratory is involved in the development of high intensity sources for the driver accelerator and on the improvements of a charge breeding system for its operation inside an highly radioactive environment. We will present the results obtained for the qualification of a 5 mAe/40 KV beam of Deuteron ions dedicated to the feeding of the driver. Concerning the heavy ions, the source PHOENIX 18/28 GHz has been chosen as injector of the driver. The optimization of the source is done in order to produce reliable beams of 1mAe / O6+ and 0.3 mAe of Ar12+ at 60 KV. Theses developments are presently done with the room temperature version of PHOENIX (including a new version of the hexapole of the source). In parallel, an upgrade version of PHOENIX, using HTS coils, is under construction and is dedicated to production of very high intensity of the Argon ions (up to 1 mAe of Ar12+). A charge breeding system is also under qualification. The PHOENIX Booster source confirms that efficiency for mass around hundred can reach up to 6%. Now the efforts consist in precisely defining the 1+ beam matching for charge breeding tuning of the source (emittance measurements). | ||
| TUPLT057 | Beam Dynamics Studies for the Fault Tolerance Assessment of the PDS-XADS Linac Design | 1282 |
|
||
| In order to meet the high availability/reliability required by the PDS-XADS design the accelerator needs to implement, to the maximum possible extent, a fault tolerance strategy that would allow beam operation in the presence of most of the envisaged faults that could occur in its beamline components. In this work we report the results of beam dynamics simulations performed to characterize the effects of the faults of the main linac components (cavities, deflecting and focusing magnets, …) on the beam parameters. The outcome of this activity is the definition of the possible corrective and preventive actions that could be conceived (and implemented in the system) in order to guarantee the fault tolerance characteristics of the accelerator. | ||
| TUPLT058 | High Intensity Linac Driver for the SPIRAL-2 Project : Design of Superconducting 88 MHz Quarter Wave Resonators (beta 0.12), Power Couplers and Cryomodules | 1285 |
|
||
| A Superconducting Linac Driver, delivering deuterons with energy up to 40 MeV (5 mA) and heavy ions with energy of 14.5 MeV/u (1 mA ), is proposed for the Spiral-2 radioactive beams facility. For the high energy section of the linac, a superconducting 88 MHz Quarter Wave Resonator (beta 0.12) has been designed and the optimisation of RF and mechanical performances will be presented. Based on the present state-of-art of the Superconducting RF technology, maximum electric surface field of 40 MV/m and magnetic surface field of 80 mT, have been adopted which should allow to reach an accelerating field of 7 MV/m (energy gain 3 MeV per resonator). A first complete prototype is under construction. The high intensity deuteron beam specifications have imposed the design of an original power coupler (maximum power 20 KW). The RF, mechanical, and thermal characteristics will be presented. The design of the cryomodule for this high energy section, integrating two QWR with its associated equipments (couplers, tuners, helium tanks), will be presented. | ||
| TUPLT059 | Evolution of Optical Asymmetries in the Elettra Storage Ring | 1288 |
|
||
| Optical asymmetries have been measured and analyzed, before and after the magnet realignments. One way is to compare theoretical to measured orbit response matrices. Another way is to analyze the measured response matrix itself, by comparing the measured effects at identical optical positions. To evaluate the effects of the sextupoles on the optical asymmetries, the measurements have been performed with the sextupoles ON and OFF. The impact of a partial realignment is also analyzed both by varying the quadrupole excitations as well as by performing dispersion and coupling measurements. The results are presented in this paper. | ||
| TUPLT060 | Production of Radioactive Ion Beams for the EXCYT Facility | 1291 |
|
||
| The EXCYT facility (EXotics with CYclotron and Tandem) at the INFN-LNS is based on a K-800 Superconducting Cyclotron injecting stable heavy-ion beams (up to 80 MeV/amu, 1 emA) into a target-ion source assembly to produce the required nuclear species, and on a 15 MV Tandem for post-accelerating the radioactive beams. After thermal ANSYS simulations, during May 2003 the Target-Ion Source assembly (TIS) was successfully tested at GANIL under the same operational conditions that will be initially used at EXCYT. Yields and production efficiencies for 8,9Li were compatible with the ones obtained at SPIRAL. Following suggestions by the Referees and the LNS Research Division, we decided to deliver 8Li as the first EXCYT radioactive beam (primary beam 13C). This choice also takes in account the availability of MAGNEX in 2004 as well as the requests and the first results obtained by the Big Bang collaboration. The commissioning of the EXCYT facility is foreseen by the end of 2004 together with the start of nuclear experiments program. In this poster we also report prospective ion beams currently in development. | ||
| TUPLT061 | Production and Transport of Radioactive Francium for Magneto-optical Trapping | 1294 |
|
||
| An innovative facility for the production and trapping of francium isotopes is operating at the INFN laboratories in Legnaro, Italy. The goal is to obtain a dense cloud of cold and possibly polarized radioactive atoms for a wide range of fundamental studies. Among them are high-resolution laser spectroscopy, alpha-decay asymmetries from deformed nuclei, and tests of the standard model at low transferred momenta. The production of francium is achieved by sending a 100-MeV oxygen-18 beam from the Tandem-XTU accelerator on a thick gold target. The extraction of Fr+ is enhanced by heating the target to 1200 K and by biasing it at +3 kV. The ions are transported to the magneto-optical trap (MOT) through a 7-m electrostatic beam line. The diagnostic systems for monitoring the beam intensity (105 ions/s) are based on silicon detectors sensitive to the alpha particles from Fr decays. Beams of stable Rb+ can also be used for optimizing the transport and trapping processes. Prior to injection into the MOT the beam is neutralized and released in atomic form by a heated yttrium or zirconium foil. Details on the production, transport and neutralization processes are presented. | ||
| TUPLT062 | Design of the Proton Beam Line for the Trade Experiment | 1297 |
|
||
| The TRADE (Triga Accelerator Driven Experiment)experiment, to be performed in the TRIGA reactor of the ENEA-Casaccia centre consists in the coupling of a 140-300 MeV, 0.5 mA proton beam produced by a cyclotron to a target hosted in the central thimble of the reactor scrammed to sub-criticality. A 30 m long beamline has been designed to transfer the beam injecting it from the top of the pool with special care of having low losses in TRIGA building where a limited shielding of the line is possible. A particular attention was paid to reduce the number and size of elements in the last part of the beamline that are immersed in the pool's water. The paper presents a description of the beam line, the design criteria and the results of beam dynamics calculations. | ||
| TUPLT063 | Laser Temporal Pulse Shaping Experiment For SPARC Photoinjector | 1300 |
|
||
| Laser for driving high brightness photoinjector have to produce UV square pulse which is predicted to be the optimum profile for emittance compensation in advanced photoinjectors. The longitudinal laser pulse distribution, according to numerical simulations for the SPARC photoinjector, must be square with rise and fall time shorter than 1 ps and flat top variable up to 10 ps FWHM. In this paper we report the results of pulse shaping obtained using an acousto-optic (AO) programmable dispersive filter (DAZZLER). The DAZZLER was used to perform spectral amplitude and phase modulation of the incoming 100 fs Ti:Sapphire pulses. Because of the finite length of the crystal the maximum duration of the shaped pulse is 6 ps. To overcome this limitation we used a configuration in which the laser pulses passed twice through the AO filter. A dispersive glass section was also used to lengthen the pulse with a single pass in the DAZZLER. In this paper we report the experimental setup, hardware description and time and frequency domain measurements. | ||
| TUPLT065 | Beams from RF Ovens and ECR Ion Sources | 1303 |
|
||
| Beam of silver, copper and recently platinum were produced with the radiofrequency oven technique. The ECRIS (Electron Cyclotron Resonance Ion Source) can be conveniently considered as a charge breeder for any injection device; this approach allows to compare the injection of metals from ovens with other techniques discussed in the literature, like the injection from mevva (Metal Vapor Vacuum Arc) sources or the injection of single charged RIB (radioactive ion beams) or the simple injection of heavy gas. Extensive experiments extracting beams of copper (charge up 13+) or silver (charge up to 19+) or xenon (charge up 20+) with the same ECRIS condition are described, and advantage of rf oven over gas injection are discussed; in particular the oven crucible can be easily voltage biased up to -400 V, to modify ECRIS plasma shape. Heating the tantalum crucibles over 2300 K (average temperature) requires careful axial alignment to avoid the formation of hot spots; preliminary evidence of this effect and its numerical modeling are also described. | ||
| TUPLT066 | Study of a High-current 176 MHz RFQ as a Deuteron Injector for the SPES Project | 1306 |
|
||
| The SPES project, aimed at the construction of a RIB facility at LNL, is initially based on the use of a primary proton beam, but it foresees a future development based on the usage of deuterons and light ions. In this article we report about the preliminary study of a 176 MHz RFQ to be used as an injector for such kind of beams. The structure explored foresees a ?four ladder? symmetric resonator, built in brazed copper. In particular beam dynamics, electrodynamics design and preliminary thermo-structural analysis of the cavity is presented. | ||
| TUPLT069 | Approaching to a Mono-modal Accelerating Cavity based on Photonic Band-gap Concepts | 1309 |
|
||
| One of the main problem of high intensity accelerators is the presence of high order modes (HOMs) which might degrade the beam quality. Accelerating cavities require HOMs suppression while keeping high quality factor (Q) fundamental mode. Both these requirements can be hardly met in closed metallic cavities. In low frequency cases and for particular geometries it is possible to partially suppress HOMs, but at high frequencies and for superconducting cavities configuration becomes cumbersome and technically unviable. We propose here a high Q cavity based on Photonic Band Gap (PBG) concepts, operating in the microwave region. The cavity consists of a two-dimensional lattice, where posts (dielectric, metallic or superconducting) are sandwiched by two conducting plates. This sandwich exhibits two kinds of frequency bands: 'pass-bands' and 'stop-bands'. It is possible to localize modes in an equivalent cavity obtained by removing posts. These modes are localized in the 'cavity'. In this way, one can obtain a quasi-mono-modal cavity: high Q fundamental mode and HOMs falling into the pass bands. We will present the study, the optimisation and the measurements of our metallic (Copper) PBG structure working in the 2-20 GHz range. The development of a different cryogenic set-up, necessary to characterise an all superconducting or an hybrid (dielectric/metallic) structure, is under way. | ||
| TUPLT070 | Study of a Linac Booster for Proton Therapy in the 30-62 MeV Energy Range | 1312 |
|
||
| Recent results in accelerator physics have shown the feasibility of a coupling scheme between a cyclotron and a linac for proton acceleration. Cyclotrons with energies up to 30 MeV, mainly devoted to radioisotopes production, are available in a large number of medical centres. These two evidences have suggested the idea to study and design a linac booster able to increase the initial proton energy up to the values required for the treatment of tumors, like the ocular ones. The main challenge in such a project is related to meet the requirements arising from the beam dynamics with the constrains due both to the mechanical structures and tolerances and to the heat dissipation mechanism chosen in the design. In this paper we will review the rationale of the project and we will discuss the basic design of a compact 3 Ghz linac with a new approach to the cavities used in a SCL (Side Coupled Linac) structure | ||
| TUPLT071 | A 5 MeV Electron Linac for Radiation Processing | 1315 |
|
||
| In recent years, radiation processing is rapidly growing in various field of industrial treatments and scientific research as a safe, reliable and economic technique. To match the requirements of several applications, a 5 MeV, 1 kW electron linac has been developed at the Dipartimento di Fisica (Università di Messina), in collaboration with the ENEA Accelerators Group (Frascati- Rome). This self- containing standing wave accelerator, driven by a 3 GHz, 2.5 MW Magnetron, has been designed, by means of the SUPERFISH and PARMELA codes, in such a way as to obtain an autofocusing structure, that will be used to develop a transportable system for 'in-situ' industrial radiography and X-ray digital tomography. For this accelerator, compact pulse forming circuits have been properly developed for the magnetron and the cathode, and pulse frequency can be varied ranging from 1 to 300 Hz, thus allowing the study of several applications of radiation processing. Main features of the accelerating structure, as well as beam spot dimensions, surface dose distribution and electron beam energy range will be described. | ||
| TUPLT072 | Dual Harmonic Acceleration with Broadband MA Cavities in J-PARC RCS | 1318 |
|
||
| In the J-PARC RCS rf system, since the fundamental rf acceleration voltage and the 2nd higher harmonic one are applied to each cavity, the impedance of hte cavity has a broadband characteristic. The Q-value of the cavity is chosen to make the higher harmonic beam loading effect as small as possible. The analysis of the amplifier and the beam loading effect on the dual harmonic rf system is described. | ||
| TUPLT073 | Observation of Coupling Resonance in HIMAC Synchrotron | 1321 |
|
||
| Coupling resonance was observed at operating points near to Qx-Qy=1. Two-dimensional profile of a beam at its equilibrium was measured, and it was found that the beam was inclined in transverse when the operating point is near to the resonance condition. We will present the detail of the measurement and the results. | ||
| TUPLT074 | Dark Current Reduction System for SPring-8 Linac | 1324 |
|
||
| The SPring-8 linac accelerates dark currents generated by its injector part up to 1 GeV. These dark currents are injected with main beam into the SPring-8 storage ring and then spoil the purity of the stored beam. The dark currents are mainly composed of a grid emission current from a thermionic gun and field emission currents from rf accelerating structures. A beam deflector for kicking only the grid emission by a pulsed electric field was developed and installed in the SPring-8 linac. We observed that the beam deflector greatly reduced the grid emission current accelerated up to 1 GeV. The measured purity of the stored single-bunched beam was about 5x10-6 when the deflector operated, which was almost 1/100 of the purity without filtering by the deflector. However, the deflector, which is installed before the prebucher, cannot reduced the field emission currents from the buncher cavities and the first acccelerating structure. These dark currents take considerable proportion of the total dark currents observed at the end of the linac. We are trying to spin off the field emission currents by weak magnetic fields across the accelerating structure generated by several coils. | ||
| TUPLT075 | Improvements of SPring-8 Linac towards Top-up Operation | 1327 |
|
||
| The top-up operation of the SPring-8 storage ring will start in May, 2004. In order to realize alternative injection into the booster synchrotron in the top-up operation and the NewSUBARU, an AC bending magnet replaced the DC bending magnet in the beam transport line to the booster synchrotron. This magnet operates at 1 Hz with a trapezoid current pattern. The 1-GeV electron beam goes at the bottom of the current pattern to the NewSUBARU or at the top of the pattern to the booster synchrotron. In order to obtain the higher reliability of the linac for the top-up operation, reinforcement of the beam monitor systems, further improvement of RF phase stability and upgrade of the control system were required. BPM?s has been newly installed in energy dispersion sections, and beam transport feedback control is in development. The phase variation in the RF system was reduced by the regulation of the gas pressure in the waveguide of the klystrons drive system. We re-engineered the VME systems to maximize availability of the linac operation considering its reliability, usability, expandability and flexibility. | ||
| TUPLT076 | Optimization of Sextupole Strengths in a Storage Ring for Top-up Operation | 1330 |
|
||
| In top-up operation of a light source, electron or positron beams are frequently injected to keep the stored current constant. Closing an injection bump orbit is thus critically important not to disturb precise experiments. However, there are sextupole magnets inside the injection bump in the SPring-8 storage ring and the bump never closes all over the bump amplitude due to the sextupole nonlinearity. To solve the problem, we proposed a scheme based on minimum condition for the injection bump leakage. The scheme only restricts the sextupole strengths within the bump. Introduction of other sextupole families outside the bump can enlarge the dynamic aperture (DA) of the ring with keeping the minimum leakage. To find the best solution, we optimized the sextupole strengths changing the number of sextupole family as a parameter. The simulation shows that addition of two sextupole families sufficiently enlarges DA. Cabling of the sextupole magnets was partly changed in the summer 2003 and the effects of the strength optimization on the bump leakage, injection efficiency and beam lifetime has been investigated experimentally. We present the obtained results compared with the simulations. | ||
| TUPLT077 | R&D Status of the Fast Extraction Kicker Magnets for the KEK/JAERI 50 GeV Synchrotron | 1333 |
|
||
| The 50 GeV proton synchrotron composes the final stage of the high intensity proton accelerator complex now on construction at JAERI/Tokai site as a joint project by KEK and JAERI. In this ring, the proton beam is accelerated from 3 GeV to 50 GeV, and delivered to the experimental facilities through the fast and slow extraction lines. The distinctive feature of the fast extraction line is that the bipolar extraction function will be provided. In normal operations, the beam is extracted toward the inner side of the ring and transported to the facility for the long baseline neutrino oscillation experiment using the Super-Kamiokande detector. In case of emergency, for example, quenches of the superconducting magnets of the neutrino line or malfunctioning of the ring RF systems, the beam is extracted toward the outer side of the ring and sent directly to the abort line with a beam dump at the end. In the current kicker design, the bipolar function will be achieved by the Symmetric Blumlein PFN (SBPFN) system with two switches on both ends. The designed parameters of the fast extraction kicker magnets and the recent hardware R&D status will be described in this paper. | ||
| TUPLT078 | Study of Impedances and Instabilities in J-PARC | 1336 |
|
||
| J-PARC consists of two high intensity proton rings with energies of 3 GeV and 50 GeV. Longitudinal impedances and instabilities, which are caused by beam chamber, cavities, kicker magnets and others, are mainly discussed in this paper. | ||
| TUPLT079 | Opposite Field Septum Magnet System for the J-PARC 50GeV Ring Injection | 1339 |
|
||
| For the injection/extraction system of the high energy high intensity proton synchrotrons, high field wide aperture thin septum magnets are required. To solve these tight problems, new design concept of opposite-field septum magnet system has been invented. The same grade of opposite magnetic field is produced both inside and outside of the septum. The electromagnetic force and leakage flux around the septum conductor are cancelled out each other. The magnetic field of the circulating beam side is compensated by two sub-bending magnets set on the up-stream and down-stream of the opposite fields septum magnet. The beam-separation angle per magnet length is twice as large as normal septum magnet and the two sub-bending magnets also have a role to extend the injection/extraction angle. The newly developed method of the opposite field septum magnets system.is applied to the injection septum magnets for the J-PARC 50-GeV proton synchrotron to get the sufficient injection angle and clearance for low loss injection. The thin septum thickness and larger kick angle at the septum magnet can be obtained by the new system, which is applicable to many accelerators. | ||
| TUPLT080 | Design of the Beam Transportation Line from the Linac to the 3-GeV RCS for J-PARC | 1342 |
|
||
| L3BT is beam transportation line from the linac to the 3-GeV RCS which is the part of the accelerators for the High-Intensity Proton Accelerator Facility Project, J-PARC. For the requirement of the beam loss minimization, the L3BT does not only connect the linac to the 3GeV RCS, but also modifies the linac beam to the acceptable shape for the 3-GeV RCS. The required beam parameters at the injection point of the RCS are momentum spread < ±0.1% (100%)and transverse emittance < 4pmm.mrad (99%). To achieve these beam qualities, the L3BT should have following functions: momentum compaction, halo scraping and beam diagnostics. In this paper, results of the design and beam simulation of the L3BT are presented. | ||
| TUPLT081 | Lattice Design of Large Acceptance FFAGs for the PRISM Project | 1345 |
|
||
| In order to realize a super muon beam that combines high-intensity, low-energy, narrow energy-spread and high purity, the PRISM project has been proposed. In this project, a FFAG ring is used as a phase rotator. In this paper, a method of designing the PRISM-FFAG lattice will be described. The PRISM-FFAG has to have both of large transverse acceptance and large momentum acceptance to achieve high intensity. Furthermore, long straight sections to install RF cavities are required to obtain a high surviving ratio of the muon. Therefore, the PRISM-FFAG requires its magnets to have large aperture and small opening angle. In such magnets, not only nonlinear effects but also magnetic fringing field are important to study the beam dynamics of FFAGs. Although using realistic 3D magnetic field maps made with programs such as TOSCA is the best solution to study the FFAG dynamics, it takes long time to make such field maps. On a design process of the PRISM-FFAG, quasi-realistic 3D magnetic field maps, which are calculated applying spline interpolation to POISSON 2D field, were used to study the beam dynamics. A program based on GEANT3.21 was used for particle tracking. | ||
| TUPLT082 | Generation of a Femtosecond Electron Beam for Nanoscience and Nanotechnology | 1348 |
|
||
| A new S-band femtosecond electron linear accelerator was developed in Osaka University for the study of radiation-induced ultrafast physical and chemical reactions in femtosecond time regions. The femtosecond electron accelerator was constructed with a laser driven photocathode RF gun, a linear accelerator (linac) and a magnetic pulse compressor. The RF gun was driven by a mode-locked Nd:YLF picosecond laser. The electron beam produced by the RF gun was accelerated in the linac with energy modulattion by adjusted the RF phase. The magnetic pulse compression, which was constructed with two 45o-bending magnets and four quadrupole magnets, is a technique to longitudinally focus a charged beam by rotating the phase space distribution in a magnetic field. The picosecond electron pulse, which was generated in the RF gun and accelerated in the linac with energy modulation, was compressed into femtosecond by adjusted the quadrupole magnetic fields. The femtosecond electron pulse is expected for the studies of ultrafast reactions in nano-space. | ||
| TUPLT085 | J-PARC Construction and its Linac Commissioning | 1351 |
|
||
| The J-PARC(Japan Proton Accelerator Research Complex) accelerator is under construction in JAERI Tokai site. The beam commissioning will be started there by the end of 2006. Prior to this, the front end of the linac was beam-commissioned in 2003 at KEK. The negative hydrogen beam with a peak current of 30 mA was accelerated up to 20 MeV by the first tank of three DTL's following the 3-MeV RFQ linac. The 324-MHz DTL contains the electro quadrupole magnets with water-cooling channels specially fabricated by means of electroforming and wire-cutting technologies. The construction status of the J-PARC accelerator is also presented. | ||
| TUPLT086 | A 40MeV Electron Source with a Photocathode for X-ray Generation through Laser-compton Scattering | 1354 |
|
||
| .3 keV femtosecond X-ray generation through laser-Compton scattering with 14MeV electron source and a TW Ti:sapphire laser was achieved. In order to increase the X-ray energy up to 15 keV for some applications, e.g. protein crystallography, we modified the system to increase electron energy. Electron beams emitted from a S-band RF photocathode are accelerated up to 40MeV with two 1.5m standing-wave linacs. The beams are bended at 90 degree using an achromatic bending system, then focused with a triplet quadrupole-magnet to be interacted with laser pulses. The characteristics of electron beams, emittance, energy and energy dispersion, will be described. | ||
| TUPLT087 | Deflection Element for S-LSR | 1357 |
|
||
| Main lattice of the ion storage and cooler ring, S-LSR is composed of 6 dipole and 12 quadrupole magnets. The maximum magnetic field, the radius of curvature and gap height are 0.95 T, 1050 mm and 70 mm, respectively. The field measurement of the dipole magnets has been completed with use of Hall-probe position controlled by driving mechanism composed of stepping motors and ball-screws. In order to cancel out the momentum dispersion, the radial electric field is superposed with the magnetic field. The radial electric field is applied by the electrodes installed into the vacuum vessel set inside the rather limited gap of the dipole magnet. Good field quality is to be realized with use of intermediate electrodes. In the present paper, the results of the magnetic field measurements are presented together with the design of the superposed electric field. | ||
| TUPLT088 | Beam Cooling at S-LSR | 1360 |
|
||
| S-LSR is an ion accumulation and cooler ring with the circumference and maximum magnetic rigidity of 22.589 m and 1.0T.m, respectively. Electron beam cooling will be applied for laser-produced hot ion beam after phase rotation. Electron cooler for S-LSR is now under construction and the beam simulation is also going on. Laser cooling of Mg ion with low energy (35 keV) is also planned in 3-dimensional way with use of Synchro-Betatron coupling.so as to realize ultra cold beam. Cancellation of shear force due to orbit-length difference in the dipole section is to be studied with use of overlapping of the radial electric field inversely proportional to the curvature radius with the uniform vertical magnetic field. Possible experiments to approach to ultra-cold beam is also to be studied by computer simulation | ||
| TUPLT089 | Status of PEFP 3MeV RFQ Development | 1363 |
|
||
| In the PEFP (Proton Engineering Frontier Project), a 350MHz, 3MeV RFQ (Radio Frequency Quadrupole) has been developed and tested. The tuning results showed that the resonant frequency is somewhat higher than 350MHz and other methods in addition to slug tuners should be used to tune the cavity correctly. To check the cavity characteristics, high power RF test has been done. The required peak RF power is 600kW and pulse width, repetition rate for initial test are 100 micro-s, 10Hz respectively. To solve the problems in PEFP RFQ, the upgrade design of 3MeV RFQ has been decided. The main concept of this upgrade design is constant vane voltage profile with the same length of RFQ. The other parameters (350MHz, 3MeV, 20mA) are the same with the previous RFQ. With constant vane voltage profile, fabrication of RFQ can be easier, and with the same mechanical dimension, other parts such as vacuum pumping station can be re-used. In this paper, the test results of the PEFP RFQ, and the details of beam dynamics design/engineering design of upgrade RFQ will be presented. | ||
| TUPLT090 | Combined Beam Dynamics Study of the RFQ and DTL for PEFP | 1366 |
|
||
| One of the goals of the Proton Engineering Frontier Project (PEFP) is to get 20 MeV proton beams of 20 mA through a 3 MeV RFQ and a 20 MeV DTL. This work is related to the combined beam dynamics study of the low energy proton accelerators in order to test the validity of the connection of the independently designed structures as well as to study the MEBT for beam transportation. | ||
| TUPLT091 | Fabrication Status of the PEFP 20 MeV DTL | 1369 |
|
||
| The PEFP (Proton Engineering Frontier Project) 20 MeV DTL have been constructed in KAERI site. The fabrication of the first tank is finished and the DT installation is in the process. We choose the pool-type electromagnets as the focusing magnet and 50 DTs will be installed on first tank. We tested the winding schemes of copper coils on the iron core and measured the magnetic field saturation.In this paper, the results of the tank fabrication and quadrupole magnet test are presented. | ||
| TUPLT092 | Optics and Magnet Design for Proton Beam Transport Line at PEFP | 1372 |
|
||
| The PEFP proton linac is designed to have two proton beam extraction lines at the 20-MeV and 100-MeV end, respectively. Each extraction line has 5 to 6 beamlines for proton beam users. The proton beam transport system for users? experiments will be prepared for this purpose. At the beginning, the beam optics for the proton beam transport system is designed with the TRACE code. The optics should be designed so as to meet the users? various requirements which might be to control the beam size and intensity at the beam target, and the timing of the proton beam. The magnet to distribute the proton beam to many beamlines is an AC magnet which has an AC frequency of 15 Hz, and is powered with a programmable AC power supply. In this paper, the result of the optics design will be presented and the magnet design will be described. | ||
| TUPLT093 | Tune Survey of Dynamic Apertures for High-brilliance Optics of the Pohang Light Source | 1375 |
|
||
| The PLS storage ring is a 2.5 GeV light source and the dynamic apertures in a lattice for the low emittance in the ring have been investigated by a simulation method. The dynamic apertures that include effects of machine errors and insertion devices were obtained by a tune survey in the simulation. It was also shown that how large are the dynamic aperture compensated after corrections of a CODs. The betatron tune for the operation of the high-brilliance lattice are investigated based on the view point of dynamic apertures obtained from a tune survey. | ||
| TUPLT095 | Precision Field Mapping System for Cyclotron Magnet | 1378 |
|
||
| A 13 MeV cyclotron has been developed by KIRAMS for radio-isotopes production such as F-18 and O-15 for positron emission tomography(PET). To characterize the cyclotron magnet precisely, a Hall probe mapping system with very high precise positioning mechanism in the Cartesian coordinate has been developed. Hall probe assembly was translated in two dimensions by two stepping motors at both sides of the Hall-probe-carrier to keep synchronously rotation sharing one step-pulse source for x-axis and one motor for y-axis. The data acquisition time had reduced to 60 minutes in full mapping by 'flying' mode. The accuracy of the measurement system is better than during the entire mapping process. In this paper the magnetic field measurement system for the cyclotron magnet is described, and measurement results are presented. | ||
| TUPLT096 | RFQ Low Level RF System for the PEFP 100MeV Proton Linac | 1381 |
|
||
| The 100MeV Proton linear accelerator (Linac) for the PEFP (Proton Engineering Frontier Project) will include a 3MeV, 350MHz RFQ(Radio-Frequency Quadrupole) Linac. The RFQ accelerates a 20mA proton beam from 50keV to 3MeV. The low level RF system for RFQ provides field control. In addition to field control, it provides cavity resonance control. An accelerator electric field stability of ± 1% in amplitude and ± 1° in phase is required for the RF system. The low level RF system has been designed and is now being fabricated. | ||
| TUPLT098 | Vertical Beam Motion in the AGOR Cyclotron | 1384 |
|
||
| Large-scale vertical excursions have been observed in the AGOR cyclotron for light ionbeams at energies close to the focussing limit (E/A =200 Q/A MeV per nucleon). With increasing radius the beam gradually moves down out of the geometrical median plane by several mm, leading to internal beamlosses. It was concluded that this effect is caused by a vertical alignment error of the coils combined with the weak vertical focussing for the beams concerned. Moving the main coils by a total of 0.37 mm has significantly improved the situation at large radii, but results in internal beamlosses for certain beams at small radii due to a large upward excursion. A systematic study of the vertical beam dynamics as a function of beam particle and energy will be presented. Possible causes and solutions will be discussed. | ||
| TUPLT099 | A Kicker Pulse Power Supply with Low Jitter | 1387 |
|
||
| The performance of kicker pulse power supplies is the main parameter to increase injection efficiency of storage ring that is an important issue for laboratory of synchrotron radiation research. The output current waveform of a kicker pulse power supply with low timing jitter is our goal for years that must satisfy the Top-Up mode injection requirement of NSRRC. In the past years kicker pulse power supplies of storage ring of NSRRC are immersed in isolation oil to sustain high voltage operational environment that led difficult to maintain, electronic component degrading and uneasy to tune parameters. Air-cooling and air-isolation is adopted in the new design structure for kicker pulse power supply system and an pre-trigger unit MA2709A is installed to trigger thyratron tube CX1536A, a kicker pulse power supply with low timing jitter 1~2ns(p-p) is obtained and could satisfy for Top-Up mode injection and maintenance is more easier than before. | ||
| TUPLT102 | Field Study of the 4T Superconducting Magnet for Rapid Cycling Heavy Ion Synchrotrons | 1390 |
|
||
| The problem of the magnetic field optimization of a 4T dipole magnet with circular aperture of 100-110 mm for rapid cycling synchrotron is considered. A single layer low inductance coil made of hollow superconducting high current cable operating at 30 kA is used. The magnetic field ramp rate up to 4 T/s should be achievable. Mathematical method to minimize sextupole and higher order non-linearities to the tolerable values by variation of angular coil turn position is developed. The results of numerical simulation for 2D part magnetic field are presented. The further possibilities to improve the field quality for similar lattice magnets and their application for heavy ion synchrotrons and boosters are discussed. | ||
| TUPLT103 | Possibilities for Experiments with Rare Radioactive Ions in a Storage Ring Using Individual Injection | 1393 |
|
||
| A radioactive ion beam produced at a target bombarded with a primary beam has after a fragment separator a relatively large emittance and small production rate. For instance, typical flux of 132Sn isotope at the exit of fragment-separator is about 5×105 ions/s. Conventionally used scheme of the ion storage in a ring based on multitutrn injection and (or) RF stacking and stochastic cooling application can not provide a high storage rate at so pure intensity especially for short lived isotopes. In this report we discuss an alternative storage scheme which is oriented to the continuous ion beam from fragment separator at production rate of 104 ions/s or even less. It is based on the fact, that at low production rate the parameters of each particle can be measured individually with rather high accuracy. The particle trajectory can be individually corrected in a transfer channel from fragment separator to the storage ring using system of fast kickers. A fast kicker in the ring synchronized with a circulating bunch provides continuous injection of the ions. The scheme permits to store the ion number required for precise mass measurements and internal target experiment. A hope to obtain large luminosity of ion-electron collisions is related with a possibility of the ion beam crystallization at small particle number. | ||
| TUPLT104 | Particle Dynamics in the Low Energy Positron Toroidal Accumulator: First Experiments and Results | 1396 |
|
||
| The project of Low Energy Particle Toroidal Accumulator (LEPTA) is dedicated to construction of a positron storage ring with electron cooling of positrons circulating in the ring. Such a peculiarity of the LEPTA enables it automatically to be a generator of positronium (Ps) atoms, which appear in recombination of positrons with cooling electrons inside the cooling section of the ring. The project has a few goals: to study electron and positron dynamics in the ring (particle motion in the horizontal and vertical planes are coupled contrary to of classic cycle accelerators), to set up first experiments with Ps in flight; Magnetic measurements of main LEPTA elements are performed. Several elements : kicker, injection system of electron beam, helical quadrupole, septum magnet are tested and expected design parameters were achieved for those elements. The investigations of electron beam dynamics are started. First results of experiments with circulating electron beam are presented and discussed in this article. Several beam diagnostic methods for studying of strong coupled motion of charged particles are proposed and tested. | ||
| TUPLT105 | Measurement of Activation Induced by an Argon Beam in a Copper Target at the SIS18 | 1399 |
|
||
| Results of the measurement of activation induced by Argon beam with energies of E=100,200,800 MeV/u in the copper target are presented. The densities of various radioactive isotopes are derived from the measurements. Long-time prediction of radioactivity and accumulated doses in the accelerator equipment is calculated. | ||
| TUPLT106 | New Developments of a Laser Ion Source for Ion Synchrotrons | 1402 |
|
||
| Laser Ion Sources (LIS) are well suited to filling synchrotron rings with highly charged ions of almost any element in a single turn injection mode. We report the first measurements of the LIS output parameters for Pb27+ ions generated by the new 100 J/1 Hz Master Oscillator - Power Amplifier CO2-laser system. A new LIS has been designed, built and tested at CERN, as an ion source for ITEP-TWAC accelerator/accumulator facility, and as a possible future source for an upgrade of the Large Hadron Collider (LHC) injector chain. The use of the LIS based on 100 J/1 Hz CO2-laser together with the new ion LINAC, as injector for ITEP-TWAC project is discussed. | ||
| TUPLT111 | RF Focusing of Low-Charge-to-Mass-Ratio Heavy-Ions in a Superconducting Linac | 1405 |
|
||
| A post-accelerator of radioactive ions (RIB linac) must produce high-quality beams over the full mass range, including uranium, with high transmission and efficiency (P.N. Ostroumov and et al., Proc. of the PAC2001, p. 4080.). The initial section of the RIB linac is a low-charge-to-mass-ratio superconducting RF linac which will accelerate any ion with q/A>=1/66 to ~900 keV/u or higher. This section of the linac consists of many interdigital cavities operating at –20 degree synchronous phase and focusing can be provided by SC solenoids following each cavity. For the charge-to-mass ratio q/A=1/66 a proper focusing can be reached with the help of strong SC solenoid lenses with magnetic fields up to 15 T. These state-of-the-art solenoids are expensive. A possible lower cost alternative focusing method based on the combination of low-field SC solenoids and RF focusing is proposed and discussed in this paper. | ||
| TUPLT112 | Radiation Damage to the Elements of the Nuclotron-type Dipole of SIS100 | 1408 |
|
||
| Radiation damage to various elements of the Nuclotron-type dipole of SIS100 sensitive to irradiation was calculated. Among the elements of consideration were the superconducting cables, insulating materials, ceramic insertions and high-current by-pass diodes. The Monte-Carlo particle transport code SHIELD was used to simulate propagation of the lost ions and protons together with the products of nuclear interactions in the material of the elements. The results for the proton projectiles were cross-checked using the particle transport code MARS, and a good agreement between the codes were found. It was found that the lifetime of the organic materials under irradiation are much more restrictive limit for the tolerable level of beam particle losses than the danger of the quench events. | ||
| TUPLT113 | Technicalities for a Novel Medium Energy Ion Accelerator | 1411 |
|
||
| Transmutation of radioactive waste,high-intensity pulsed sources of fast neutrons,problem of inertially-confined fusion and a lot of different problems of science and technology put increased demands on the linear high power medium energy proton and heavy ion accelerators.But these accelerators are presently massive,huge and very expansive,which restrict now and in a near future their wide use and motivates the study of altenetive methods to achieve the design current,power and economic characteristics.This report decribes the present reseach on attaining high power medium energy ion beams,using novel idea for accelerator design.Theoretical proposal and preliminary conceptual design for the accelerator,based on a principle of free flying ion emitter("ballistic anode"),were discussed first a few years ago.The principle involves a high potencial difference generated only for a short time in the special vacuum chamber,but not steady-state conditions.Now,we would like to discuss next problems:1.technicalities of the ballistic anode design,both for proton and heavy ion beams generation.2 pulse power multiplication.3.high current sources for charge pumping of the ballistic anode.4 experimental modelling. | ||
| TUPLT117 | Test of Materials for the High Temperature Intense Neutron Target Converter | 1413 |
|
||
| Nowadays in LNL INFN (Italy) the project for gain and study of short-lived radioactive isotopes is in progress [1]. The intense neutron target is required for these goals. In BINP, Russia, the design of high temperature target cooled by radiation is proposed. Presented paper describes the results of preliminary test of materials for the target converter: MPG6-brand graphite, graphite material on the basis of 13C, boron carbide, glassy carbon. Test included the distributed heating over volume of samples with the electron beam up to conditions, simulating the converter working regime (heating power density up to 1300 W/cm2, temperature up to 20000C, temperature gradient up to 1000C/mm). Graphite materials show its adaptability under conditions specified. | ||
| TUPLT118 | Test of Construction for High Temperature Intense Neutron Target Prototype | 1416 |
|
||
| Within the framework of the creation of the high temperature intense neutron target prototype, the thermal tests of the preliminary design were done in BINP. Tests were aimed at experimental definition of temperature and heat flux distribution over the construction, heat transfer via the contact areas between materials selected, specifying the properties of these materials. This paper presents the experimental test results as well as the comparison of experimental data with the results of numerical simulation of the working regimes of the construction. | ||
| TUPLT120 | Commissioning of Electron Cooler EC-300 | 1419 |
|
||
| The article deals with the commissioning of electron cooler EC-300. It was designed and manufactured for CSR experiment (IMP, Lanzhou, China) by BINP, Russia. The energy of electron beam is up to 300 keV, the electron current is up to 3 A, the magnetic field in the cooling section is up to 1.5 kG. The major innovation of the cooler is the variable profile of electron beam, the electrostatic bends of the electron beam and the system of the magnetic field correction. During commissioning the linearity of the magnetic field 10-6 was obtained, the recuperation efficiency was observed up 10-6 , the pressure of residual gas in the vacuum chamber was 5· 10-11 torr during operation with the electron beam. The CSRe cooler for IMP is a new step at cooling technique and the first results achieved during commissioning are very interesting for accelerator physics. | ||
| TUPLT121 | Compact Tandem Accelerator Based Neutron Source for the Medicine | 1422 |
|
||
| Status of original heavy hydrogen ion electrostatic accelerator-tandem is described. Potential electrodes with vacuum insulation organize tract for accelerating ion beam before and after gas stripper, located inside the high voltage electrode. There are no accelerating tubes in the tandem proposed. 20 kHz, 10 kW, 500 kV compact sectioned rectifier is a high voltage source. Both the geometry of neutron source and results of the rectifier testing are presented. Estimation of yield and space-energy distribution of neutron, as a result of nuclear reactions produced by heavy hydrogen ion in beryllium or carbon targets are given. Result of Monte-Carlo simulation of neutron and photon transferring for these sources of neutron is the distribution of the absorbed dose incide phantom. Result of the simulation are compared with result of the experiment. The possibility of use of this neutron source for the neutron or neutron capture therapy is discussed too. | ||
| TUPLT124 | DESIREE - A Double Electrostatic Storage Ring | 1425 |
|
||
| The advantages of storage rings with only electrostatic elements were first demonstrated by ELISA in Aarhus and later in other places. At MSL and Fysikum at Stockholm University the ideas have been developed further in the Double Electrostatic Storage Ion Ring ExpEriment, DESIREE. Beams of negative and positive ions will be merged in a common straight section of the rings so that low energy collisions can be studied. Furthermore the rings will be cooled to 10 - 20 K in order to relax internal excitations in circulating molecules. A design report can be found at www.msl.se. The project is now (January 2004) almost fully financed and the final design work has recently been started. The paper will shortly review the physics programme and describe the status of the design work. | ||
| TUPLT128 | The Operation Modes of Kharkov X-ray Generator based on Compton Scattering NESTOR | 1428 |
|
||
| The results of theoretical and numerical considerations of linear Compton scattering are used to evaluate characteristics of X-rays produced by collision between a low emittance electron beam and intensive laser light in an X-rays generator NESTOR of NSC KIPT. Two main generation modes have been under consideration at preliminary NESTOR design. There are the operation mode for medicine 33.4 keV X-rays production using 43 Mev electron beam and Nd:YAG laser beam and higher energy X-rays production mode providing X-rays with energy up to 900 keV with 225 MeV electron beam and Nd:YAG laser beam. It is supposed to use an optical cavity for laser beam accumulation of about 2.6 m long and an interaction angle of about 30 in both operation modes. A few more operation modes provide possibility to expand operation range of NESTOR. Using interaction angle 100 and 1500 along with optical resonator 42 or 21 cm long and the second mode of laser light it is possible to produce X-rays in energy range from a few keV till 1.5 MeV. The intensity and spectral brightness of the X-rays is expected to be ~ 1013 phot/s and ~ 1013 phot/s/mm2/mrad2/0.01%BW respectively. | ||
| TUPLT129 | NESTOR Reference Orbit Correction | 1431 |
|
||
| It is known that intensity of scattered radiation in X-rays generators based on Compton scattering strongly depends on relative position of electron and laser beams. For this reason it is very important to have effective system of reference orbit correction and beam position control as well along whole ring as at the interaction point. In the paper the results of design and development of reference orbit correction system for compact storage ring NESTOR are presented. The total reference orbit correction will be carried out in vertical plane only. Correctors will be disposed on quadrupole lenses and will be provide reference orbit correction angle up to 0.10. The local correction at the interaction point will be provided with four correctors located at the interaction straight section. In the article results of calculations, layout of whole system, quadrupole lenses and pick-up station parameters and schemes are presented. | ||
| TUPLT132 | Investigation of Injection through Bending Magnet Fringe Fields in X-rays Source NESTOR | 1434 |
|
||
| In paper injection in the X-rays source NESTOR through fringe fields of a bending magnet is considered. The simulation of a motion of a beam of charged particles through 3-d fields of magnetic devices of the injection channel, which ones is located on a ring, are performed. The focusing properties of the injection channel are determined. | ||
| TUPLT133 | Test Results of Injector Based on Resonance System with Evanescent Oscillations | 1437 |
|
||
| Report presents results of tune-up and tests of the compact electron S ? band injector consisting of the low-voltage diode electron gun and the bunching system based on the resonant system with the evanescent oscillation. In the considered bunching system electrical field increased from beam entrance to an exit of the buncher. The injector designed for bunching of electron beam with initial energy of 25 keV and pulse current of 300 mA and accelerating it to the energy of 1 MeV. | ||
| TUPLT134 | Lattice of NSC KIPT Compact Intense X-ray Generator NESTOR | 1440 |
|
||
| The new generation of the intense X-rays sources based on low energy electron storage ring and Compton scattering of laser beam allows to produce X-rays with intensity up to 1014 phot/s. One of the main traits of a storage ring lattice for such generator type is using of magnetic elements with combined focusing functions such as bending magnets with quadrupole and sextupole field components. In combination with very low bending radius and dense magnetic elements setting along ring circumference it leads to increasing of 3D magnetic field effects on electron beam dynamics and can decrease generated radiation intensity drastically. For the reasons of very low electron beam size at the interaction point and strong focusing in a compact storage ring the questions of determination of accuracy of bending magnet is very important too. The paper is devoted to the description of lattice of NSC KIPT Compact X-ray generator NESTOR. The results of investigations of the effects of 3D magnetic field and harmonic compound due to manufacture errors of bending magnets, bending magnet and lenses edges on electron beam dynamics are presented. | ||
| TUPLT136 | Proton Beam Line for the ISIS Second Target Station | 1443 |
|
||
| The ISIS facility, based at the Rutherford Appleton Laboratory in the UK, is an intense pulsed source of Muons and Neutrons used for condensed matter research. The accelerator facility delivers an 800 MeV proton beam of 2.5x1013 protons per pulse at 50 Hz. As part of the facility upgrade, which includes increasing the source intensity to 3.7x1013 protons per pulse using a dual harmonic RF system, it is planned to share the source with a second, 10 Hz, target station. A beam line supplying this target will extract from the existing target station beam line. Measurements and models characterising the optical functions around the extraction point of the existing line are discussed. The optical design, diagnostics and beam correction systems for second target station beam line are presented. | ||
| TUPLT137 | Comparative Simulation Studies of Electron Cloud Build-up for ISIS and Future Upgrades | 1446 |
|
||
| Electron cloud effects currently limit the performance of several proton accelerators operating with high beam current. Although ISIS, the 160 kW 70-800 MeV proton synchrotron at the Rutherford Appleton Laboratory (UK), has never appeared to be affected by the problem in its 15 years of operations, e-p instabilities could potentially be a cause of concern for future machine upgrades to higher beam powers. In this paper we review the present status of simulations for ISIS and compare it to preliminary results for two upgrade options: a 0.5MW 180-800 MeV scheme and a 1MW 0.8-3 GeV scheme with an additional synchrotron using ISIS as a booster (see C. Prior et al., ISIS megawatt upgrade plans, in Proceedings of the 2003 Particle Accelerator Conference PAC 2003, Portland, Or, USA). | ||
| TUPLT138 | A Fast Beam Chopper for Next Generation High Power Proton Drivers | 1449 |
|
||
| The identification and development of a successful beam chopper design is regarded as key for the European Spallation Source (ESS), and for all next generation high intensity proton driver schemes that adopt the linac-accumulator ring configuration. A description is given of refinements to the beam line design of a 'Tandem' chopper system, developed to address the requirements of the ESS. Particle tracking using the 'General Particle Tracer' (GPT) code has enabled efficient optimisation of beam apertures, and the analysis of beam power density distributions on chopper beam dumps. Preliminary results of 'proof of principle' testing on prototype fast, and slower transition high voltage pulse generators, are presented. | ||
| TUPLT139 | Extending the Duty Cycle of the ISIS H Minus Ion Source, Thermal Considerations | 1452 |
|
||
| The ISIS H minus ion source is currently being developed on the Ion Source Development Rig (ISDR) at Rutherford Appleton Laboratory (RAL) in order to meet the requirements for the next generation of high power proton drivers. One key development goal is to increase the pulse width and duty cycle, but this has a significant effect on ion source temperatures if no other changes are made. A Finite Element Analysis (FEA) model has been produced to understand the steady state and dynamic thermal behavior of the source, and to investigate the design changes necessary to offset the extra heating. | ||
| TUPLT140 | Redesign of the ISIS Main Magnet Power Supply Storage Choke | 1455 |
|
||
| The ISIS facility, based at the Rutherford Appleton Laboratory in the UK, provides intense pulsed neutron and muon beams for condensed matter studies. As part of the facilities upgrade and refurbishment program, the 1MJ storage choke which forms part of the main magnet power supply system, will be replaced with a number of smaller units. The present storage choke, which consists of a split secondary winding transformer, is incorporated into a series-parallel resonant circuit known as the 'white circuit'. This circuit ensures that each magnet receives identical currents, but is not subjected to excessive voltages. Although the storage choke is essentially a transformer, its secondary magnetising inductance is relatively low and a precisely defined value. This paper discusses the design and development of ten smaller units which will eventually replace the present equipment, and the testing of a one fifth scale model, which will be used to prove the technology. | ||
| TUPLT141 | The Effect of Extraction Geometry on the Measured ISIS H Minus Ion Source Beam | 1458 |
|
||
| Recent Finite Element Analysis (FEA) electromagnetic modelling of the extraction region of the ISIS H minus source has suggested that the present set up of extraction electrode and 90 degree sector magnet is sub-optimal, with the result that the beam profile is asymmetric, the beam is strongly divergent in the horizontal plane and there is severe aberration in the focusing in the vertical plane. The FEA model of the beam optics has demonstrated that relatively simple changes to the system should produce a dramatic improvement in performance. These changes have been incorporated on the Ion Source Development Rig (ISDR) at Rutherford Appleton Laboratory (RAL), and their effects on the H minus beam are presented here. | ||
| TUPLT142 | Status of Design of Muon Beamline for the Muon Ionisation Cooling Experiment | 1461 |
|
||
| The MICE collaboration proposes to install a Muon Ionisation Cooling Experiment at the ISIS facility, at Rutherford Appleton Laboratory. This experiment will be the first demonstration of ionisation cooling as a means to reduce the large transverse emittance of the muon beam, produced during the early stages of a neutrino factory. In order to permit a realistic demonstration of cooling, a source of muons must be produced, possessing particular qualities, notably in emittance and momenta. This paper describes the present design for the muon beamline source, and the plans for its implementation at RAL. | ||
| TUPLT143 | Studies of Beam Loss Control on the ISIS Synchrotron | 1464 |
|
||
| The ISIS Facility at the Rutherford Appleton Laboratory in the UK produces intense neutron and muon beams for condensed matter research. The ISIS 800 MeV Proton Synchrotron presently provides up to 2.5·1013 protons per pulse at 50 Hz, corresponding to a mean power of 160 kW. A dual harmonic RF system upgrade is expected to increase the intensity and power by about 50%. The tighter constraints expected for higher intensity running are motivating a detailed study of beam loss distributions and the main factors affecting their control. Main aims are maximising the localisation of activation in the collector straight, and minimising risk of damage to machine components. The combination of experimental work, developments of the loss measurement systems, and simulation studies are summarised. Key factors considered include: the effects of primary collector geometry and material; the nature of the beam loss; and methods for experimentally determining spatial loss distributions. | ||
| TUPLT144 | Upgrade of the ISIS Main Magnet Power Supply | 1467 |
|
||
| ISIS, situated at the Rutherford Appleton Laboratory (RAL) is the world?s most powerful pulsed neutron source. At the heart of the ISIS accelerator is a proton synchrotron which uses a ring of magnets connected in series and configured as a ?White Circuit?. The magnets are connected in series with capacitor banks so that they form a resonant circuit with a fundamental frequency of 50 Hz. The circuit allows the magnets to be fed with an AC current superimposed on a DC current. The AC is currently provided by a 1MVA Motor-Alternator set and it is now proposed to replace this by a solid state UPS (Uninterruptible Power Supply) system. Tests on a smaller 80kVA unit have shown that it is possible to control the magnet current with a modified UPS system in such a way that both the frequency, phase and output voltage are under the direct influence of the control system. This paper discusses the issues surrounding the upgrading of AC supply to the main magnets with a view to improving the system reliability, improving magnet current stability and reducing the risk of mains failure. | ||
| TUPLT145 | Transverse Coupling Measurement using SVD Modes from Beam Histories | 1470 |
|
||
| In this report we investigate the measurement of local transverse coupling from turn-by-turn data measured at a large number of beam position monitors. We focus on a direct measurement of coupled lattice functions using the Singular Value Decomposition (SVD) modes and explore the accuracy of this method. The advantages and shortcomings of this model-independent method for coupling measurement will be also discussed. | ||
| TUPLT146 | Techniques to Extract Physical Modes in Model-independent Analysis of Rings | 1473 |
|
||
| SVD mode analysis is a basic techinique in Model-Independent Analysis of beam dynamics. It decomposes the spatial-temporal variation of a beam centroid into a small set of orthogonal modes based on statistical analysis. Although such modes have been proven to be rather informative, each orthogonal mode may not correspond to an individual physical source but a mix of several in order to be orthogonal. Such mixing makes it difficult to quantitatively understand the SVD modes and thus limits their usefulness. Here we report a new techinique to untangle the mixed modes in storage ring analysis based on the fact that most of the physical modes in a ring have identifiable characteristics in frequency domain. | ||
| TUPLT147 | Multiple-charge-state Beam Steering in High-intensity Heavy-ion Linacs | 1476 |
|
||
|
An algorithm suitable for correction to steering of multiple-charge-state beams in heavy-ion linacs operating at high currents has been developed [*]. It follows a four-dimensional minimization procedure that includes coupling of the transverse beam motions. A major requirement is that it obeys the restricted lattice design imposed by the acceleration of multiple-charge-state heavy-ion beams [**]. We study the algorithm efficiency in controlling the beam effective emittance growth in the presence of random misalignments of cavities and focusing elements. Limits on misalignments are determined by quantifying beam losses and effective steering requirements are selected by examining several correcting schemes within the real-state constraints. The algorithm is used to perform statistically significant simulations to study beam losses under realistic steering.
* E. S. Lessner and P. N. Ostroumov, Proc. Part. Accel. Conf. (2003)** P. N. Ostroumov, Phys. Rev. STAB Vol. 5, 0030101 (2002) |
||
| TUPLT149 | Beam Manipulation and Compression Using Broadband RF Systems in the Fermilab Main Injector and Recycler | 1479 |
|
||
| Successful tests of new method for beam manipulation, compression, and stacking using the broadband RF systems in the Fermilab Recycler and Main Injector are described. Under usual conditions an unbunched beam can be confined to a fraction of the azimuth of the ring by a set of "Barrier Pulses" which repel particles trying to escape from the ends of the segment of beam. One way to compress or expand the azimuthal extent of the segment of beam is to slowly change the distance between barrier pulses. However when it is desired to rapidly compress or expand the length of the segment, a linear ramp can be superimposed on the waveform between barrier pulses. This causes particles at the front and back of the beam segment to be accelerated or decelerated by differing amounts, and the velocity correlation along the length of the beam segment causes it to expand or contract. When the expansion or contraction is halfway completed, the ramp voltage is reversed so the all particles will come relatively to rest at the end of the process. With the Barrier pulses following appropriately, no particles leak out the ends of the beam segment and the emittance is preserved. | ||
| TUPLT150 | Vector Sum Control of an 8 GeV Superconducting Proton Linac | 1482 |
|
||
| Fermilab is investigating the feasibility of an economical 8 GeV superconducting linac for H-. In order to reduce the construction costs it is considered to fan out the rf power to a string of accelerating structures per klystron. Below 1 GeV the individual fluctuations of the cavities will be compensated by high power phase shifters, above 1 GeV the longitudinal dynamics are sufficiently damped to consider omitting the phaseshifters. The impact of this setup on the field stability of individual cavities and ultimately the beam energy has been studied. | ||
| TUPLT151 | Status of the Fermilab Electron Cooling Project | 1485 |
|
||
| Fermilab has constructed and commissioned a full-scale prototype of a multi-MV electron cooling system to be installed in the 8.9 GeV/c Fermilab Recycler ring. This prototype was used to test all of the electron beam properties needed for cooling. However, because the prototype is not located within proximity of the Recycler ring, the actual electron cooling of antiprotons can not be demonstrated until it is relocated. The Fermilab electron cooling R&D project is scheduled to be completed in May, 2004 at which time it will be disassembled and relocated to a newly constructed facility where it will be installed in the Recycler. This paper describes the experimental results obtained with the prototype cooler system, gives an overview of the new electron cooling facility, and discusses the overall status of the project. | ||
| TUPLT153 | Orbit Response Matrix Analysis Applied at PEP-II | 1488 |
|
||
| Beam-based techniques to study lattice properties have proven to be a very powerful tool to optimize the performance of storage rings. The analysis of orbit response matrices has been used very successfully to measure and correct the gradient and skew gradient distribution in many accelerators. The first applications were mostly in synchrotron light sources, but the technique is also used increasingly at colliders. It allows determination of an accurately calibrated model of the coupled machine lattice, which then can be used to calculate the corrections necessary to improve coupling, dynamic aperture and ultimately luminosity. At PEP-II, the Matlab version of LOCO has been used to analyze coupled response matrices for both the LER and the HER. The large number of elements in PEP-II and the very complicated interaction region present unique challenges to the data analysis. The orbit response matrix analysis will be presented in detail, as well as results of lattice corrections based on the calibrated machine model. | ||
| TUPLT154 | Aperture Studies for the Fermilab AP2 Anti-proton Line | 1491 |
|
||
| The AP2 beamline transports anti-protons from the production target to the Debuncher ring. In the past the observed aperture has been smaller than that estimated from linear, on-energy optics. We have investigated possible reasons for the aperture limitation and have identified possible sources, including residual vertical dispersion from alignment errors and chromatic effects due to very large chromatic lattice functions. Some experiments have already been performed to study these effects. We present results of the experimental and theoretical studies and possible remedies. | ||
| TUPLT156 | Progress in Ideal High-intensity Unbunched Beams in Alternating Gradient Focusing Systems | 1494 |
|
||
|
A persistent challenge in high-intensity accelerator design is the optimization of matching conditions between a beam injector and a focusing system in order to minimize non-laminar flows, envelope oscillations, emittance growth, and halo production. It has been shown [*] that the fluid motion of a thin space-charge dominated beam propagating through a linear magnetic focusing channel consisting of any combination of uniform or periodic solenoidal fields and alternating gradient quadrupole fields can be solved by a general class of corkscrewing elliptic beam equilibria. The present work extends this discussion to asymmetric PPM focusing and derives conditions under which a uniform density elliptical beam can be matched to such a focusing channel by considering the fluid equilibrium in the paraxial limit. Methods of constructing such a beam are also discussed, with particular attention devoted to analytic electrode design for Pierce-type gun diodes of elliptical cross-section. Several applications are discussed, including heavy-ion fusion and a high-efficiency ribbon beam microwave amplifier for accelerator applications.
* C. Chen, R. Pakter, R. Davidson, "Ideal Matching of Heavy Ion Beams," Nucl. Inst. And Methods, A 464 (2001) p. 518-523 |
||
| TUPLT159 | First Commissioning Experiments at DARHT-II | 1497 |
|
||
| The second axis of the Dual Axis Radiographic Hydro-Test (DARHT) facility will provide up to four short(< 150 ns) radiation pulses for flash radiography of high-explosive driven implosion experiments[1]. The DARHT-II linear induction accelerator (LIA) will produce a 2-kA,18-MeV,2-micro-s electron beam. A fast kicker will cleave four short pulses out of the beam, which will focused onto a tantalum target for conversion to bremsstrahlung pulses for radiography. The first tests of the second axis accelerator were designed to demonstrate the technology, and to meet the modest performance requirements for closing out the DARHT-II construction project. These experiments demonstrated that we could indeed produce a 1.2 kA beam with pulse length 0.5-1.2 s and accelerate it to 12.5 MeV. These de-rated parameters were chosen to minimize risk of damage in these first experiments with this novel accelerator. The beam was stable to the BBU instability for these parameters. In fact, we had to reduce the magnetic guide field by a factor of 5 before any evidence of BBU was observed. We will discuss the results of these experiments and their implications, as well as our plans for continuing with DARHT-II commissioning. | ||
| TUPLT160 | Development of a 25-mA, 12% Duty Factor (df) H- Source for LANSCE | 1500 |
|
||
| Present operations at the Los Alamos Neutron Science Center (LANSCE) accelerator use a surface conversion source to provide 80-keV, 16 to 18-mA H- beams with typical rms normalized emittance of 0.13 (pmm-mrad). Operational flexibility of the 800-MeV linac and proton storage ring will be increased by a higher current H- source. The present goal is to achieve a 25-mA H- surface converter source with modest (10-20%) emittance increase without sacrificing the present LANSCE production source 12% df and 28 day lifetime. The LANSCE 80-kV ion source test stand (ISTS) has been brought into reliable 24-hour per day operation with computer control and modern electronics. A fourth production source has been fabricated, and is now operating on the ISTS. H- currents up to 25mA have been observed with 0.15 to 0.18(pmm-mrad) rms normalized emittances. An experimental study of surface converter geometries and electron filters at the emitter electrode are planned to optimize source current and emittance. | ||
| TUPLT161 | Normal Form Analysis of Linear Beam Dynamics in a Coupled Storage Ring | 1503 |
|
||
| The techniques of normal form analysis, well known in the literature, can be used to provide a straightforward characterization of linear betatron dynamics in a coupled lattice. Here, we consider both the beam distribution and the betatron oscillations in a storage ring. We find that the beta functions for uncoupled motion generalize in a simple way to the coupled case. Defined in the way that we propose, the beta functions remain well behaved (positive and finite) under all circumstances, and have essentially the same physical significance for the beam size and betatron oscillations as in the uncoupled case. Application of this analysis to the online modeling of the PEP-II rings is also discussed. | ||
| TUPLT162 | Computation of the Longitudinal Space Charge Effect in Photoinjectors | 1506 |
|
||
| The LCLS Photoinjector produces a 100A, 10 ps long electron bunch which is later compressed down to 100 fs to produce the peak current required for producing SASE radiation. SASE saturation will be reached in the LCLS only if the emittance and uncorrelated energy spread remain respectively below 1.2 mm.mrad and 5. 10-4. This high beam quality will not be met if the Longitudinal Space Charge (LSC) instability develops in the injector and gets amplified in the compressors. The Longitudinal Space Charge instability originates in the injector beamline, from an initial modulation of the current density. Numerical computations, performed with Multiparticle Space Charge tracking codes, showing the evolution of the longitudinal phase space along the LCLS Photoinjector beamline, are presented. Those results are compared with an analytical model for various regimes of energy and acceleration. This study justifies the necessity to insert a "laser heater" in the LCLS Photoinjector beamline to warm up the beam and thus prevent the amplification of the LSC instability in the compressors. Numerical calculations of the 'laser heater' performances are presented. | ||
| TUPLT163 | Achieving Beam Quality Requirements for Parity Experiments at Jefferson Lab | 1509 |
|
||
| Measurement of asymmetry between alternating opposite electron polarization in electron-nucleon scattering experiments can answer important questions about nucleon structures. Such experiments impose stringent condition on the electron beam quality, and thus the accelerator used for beam creation and delivery. Of particular concern to such ?parity? experiments is the level of correlation between beam characteristics (orbit, intensity) and electron polarization that can obscure the real asymmetry. This can be introduced at the beam forming stage, created due to scraping, or not damped to desired level due to defective transport. Suppression of such correlation thus demands tight control of the beam line from cathode to target, and requires multi-disciplined approach with collaboration among nuclear physicists and accelerator physicists/engineers. The approach adopted at Jefferson Lab includes reduction of correlation source, improving low energy beam handling, and monitoring and correcting global transport. This paper will discuss methods adopted to meet the performance criteria imposed by parity experiments, and ongoing research aimed at going beyond current performance. | ||
| TUPLT164 | CEBAF Injector Achieved World's Best Beam Quality for Three Simultaneous Beams with a Wide Range of Bunch Charges | 1512 |
|
||
| The CEBAF accelerator simultaneously provides three 499 MHz interleaved continuous electron beams spanning 5 decades in beam intensity (a few nA to 200 uA) to three experimental halls. The typical three-user physics program became more challenging when a new experiment, G0, was approved for more than six times higher bunch charge than is routine. The G0 experiment requires up to 8 million electrons per bunch (at a reduced repetition rate of 31 MHz) while the lowest current hall operates at 100 electrons per bunch simultaneously. This means a bunch destined to one hall may experience significant space charge forces while the next bunch, for another hall, is well below the space charge limit. This disparity in beam intensity is to be attained while maintaining best ever values in the beam quality, including final relative energy spread (<2.5x 10-5 rms) and transverse emittance (<1 mm-mrad norm. rms). The difficulties related to space charge emerge in the 10m long, 100 keV section of the CEBAF injector during initial beam production and acceleration. A series of changes were introduced in the CEBAF injector to meet the new requirements, including changes in the injector setup, adding new magnets, replacing lasers used for the photocathode and modifying typical laser parameters, stabilizing RF systems, and changes to standard operating procedures. In this paper, we will discuss all these modifications in some detail including the excellent agreement between the experimental results and detailed simulations. We will also present some of our operational results. | ||
| TUPLT165 | A PARMELA Model of the CEBAF Injector valid over a Wide Range of Parameters | 1515 |
|
||
| A pre-existing PARMELA model of the CEBAF injector has been recently verified using machine survey data and also extended to 60 MeV region. The initial distribution and temperature of an electron bunch are determined by the photocathode laser spot size and emittance measurements. The improved injector model has been used for extensive computer simulations of the simultaneous delivery of the Hall A beam required for a hypernuclear experiment, and the Hall C beam, required for a parity experiment. The Hall C beam requires a factor of 6 higher bunch charge than the Hall A beam, with significantly increased space charge effects, while the Hall A beam has an exceedingly stringent energy spread requirement of 2.5x 10-5 rms. Measurements of the beam properties of both beams at several energies (100 keV, 500 keV, 5 MeV, 60 MeV) and several values of the bunch charge were performed using the standard quad-wire scanner technique. Comparisons of simulated particle transmission rate, longitudinal beam size, transverse emittance and twiss parameters, and energy spread against experimental data yield reasonably good agreement. The model is being used for searching for optimal setting of the CEBAF injector. | ||
| TUPLT166 | Beam Invariants for Diagnostics | 1518 |
|
||
| This paper deals with some measurable quantities of beams preserved under symplectic transformations. General beam distributions have no determined area, and rms quantities of the beam do not provide invariants in general nonlinear case. It is shown, though, that in the 1D case there exist some integral and local invariants, directly linked to Liouville's theorem. Beam invariants, related to general properties of symplectic transformations, are also found and presented for 2D and 3D cases. If measured at different locations, they can tell whether the transformation is symplectic or there exist diffusion, friction, or other non-Hamiltonian dynamic processes in the beam. | ||
| TUPLT167 | Installation of the Spallation Neutron Source (SNS) Warm Linac | 1521 |
|
||
| The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built at Oak Ridge National Laboratory. The SNS project design and construction is a partnership involving six DOE national laboratories including Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Oak Ridge, and Los Alamos. When completed in 2006, the SNS will provide the most intense, pulsed neutron beams in the world for scientific research and industrial development. At the present time we are installing and commissioning the warm linac system, designed by Los Alamos, and have to date had good success. The warm linac is comprised of six Drift Tube Linac (DTL) tanks and four Coupled Cavity Linac (CCL) modules. These accept an incoming negative hydrogen ion beam from the Front End injector at 2.5 MeV, and accelerate to a final energy of 185 MeV. At this time we have installed and commissioned DTL tanks 1-3 and installed CCL module 1 . Experience and information gained during installation will be presented. The performance in terms of alignment, vacuum and field tuning will be described. | ||
| TUPLT168 | SNS Beam Commisioning Status | 1524 |
|
||
| The Spallation Neutron Source accelerator systems will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. The accelerator complex consists of an H- injector capable of producing 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The linear accelerator consists of a Drift Tube Linac, a Coupled-Cavity Linac and a Superconducting Linac which provide 1.5 mA average current to the accumulator ring. The staged beam commissioning of the accelerator complex is proceeding as component installation progresses. In three separate beam commissioning runs, the H- injector and Drift Tube Linac tanks 1-3 have been commissioned at ORNL. Several important performance goals have been achieved, namely 38 mA peak beam current, 1 msec beam pulse length and 1 mA average beam current. Results and status of the beam commissioning program will be presented. | ||
| TUPLT170 | The SNS Beam Power Upgrade | 1527 |
|
||
| The Spallation Neutron Source (SNS) accelerator systems, which consist of an H- injector, a 1 GeV linear accelerator, an accumulator ring and associated transport lines, will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. The SNS is presently under construction at Oak Ridge National Laboratory and will begin operations in 2006. Even in the baseline design, many of the accelerator subsystems are capable of supporting higher beam intensities and higher beam energy. We report on upgrade scenarios for the SNS accelerator systems which increase the 1.44 MW baseline beam power to at least 3 MW, and perhaps as high as 5 MW. The increased SNS beam power can be achieved primarily by increasing the H- ion source current, installing additional superconducting cryomodules to increase the final linac beam energy to 1.3-1.4 GeV, and modifying injection and extraction hardware in the ring to handle the increased beam energy. The upgrade beam parameters will be presented, the required hardware modifications will be described, and the beam dynamics implications will be discussed. | ||
| TUPLT171 | ORBIT Simulations of the SNS Accumulator Ring | 1530 |
|
||
| As SNS undergoes construction, many detailed questions arise concerning strategies for commissioning and operating the accumulator ring. The ORBIT Code is proving to be an indispensible tool for addressing these questions and for providing guidance to the physicists and decision makers as operation draws near. This paper shows the application of ORBIT to a number of ring issues including exclusion of the HEBT RF cavities during commissioning, the detailed effect of the injection chicane magnets on the beam, the effects and correction of magnet alignment and multipole errors, debunching of the linac 402.5 MHz beam structure, the injection of self consistent uniform beam configurations, and initial electron cloud simulations. | ||
| TUPLT172 | Measurement of Halo Mitigation Schemes for the Spallation Neutron Source Linac | 1533 |
|
||
| A series of emittance measurements were performed at the end of Drift Tube Linac tank 1 of the Spallation Neutron Source to verify experimentally the previously proposed halo generation mechanism and its mitigation schemes [1]. The emittance measurements clearly showed a visible reduction in the halo as well as a significant reduction in the rms emittance when the proposed round beam optics is employed. This confirms experimentally the halo generation mechanism we identified. | ||
| TUPLT173 | Experimental Test of Transverse Matching Routine for the SNS Linac | 1536 |
|
||
| Transverse matching for a high intensity linac was proposed based on minimizing rms emittances. A MATLAB routine was developed and applied during the SNS linac commissioning. The result was also compared with the simulations. | ||
| TUPLT175 | Operation of the SNS Ion Source at High Duty-Factor | 1538 |
|
||
| The ion source for the Spallation Neutron Source* (SNS) is a radio frequency, multi-cusp, source designed to deliver ~ 45 mA of H- with a normalized rms emittance of less than 0.2 pi mm mrad to the SNS accelerator. Once the SNS is fully operational a beam current duty factor of 6% (1 ms pulse length, repetition rate of 60 Hz) will be required from the ion source. To date, the source has been utilized in the early commissioning of the SNS accelerator and has already demonstrated stable, satisfactory operation at beam currents of ~30 mA with duty factors of ~0.1% for operational periods of several weeks. This work summarizes the results of a series of lifetime tests performed at a dedicated ion source test facility where the source was pushed closer to the operational goal of 6% duty factor. | ||
| TUPLT177 | RHIC Optics Measurements at Different Working Point | 1541 |
|
||
| Working point scans at RHIC were performed during 2004 to determine the effect on lifetime and luminosity. Linear optics were measured for different working point tunes by exciting coherent oscillations with the aid of RHIC AC dipoles. Two methods to measure the beta functions and phases are presented and compared: a conventional technique, and a new method based on singular value decomposition (SVD). The performance of a 3-bump beta wave algorithm to identify quadrupole error sources is also presented. | ||
| TUPLT179 | Mini-bunched and Micro-bunched Slow Extracted Beams from the AGS | 1544 |
|
||
| BNL's AGS has a long history of providing slow extracted proton beams to fixed target experiments. This program of providing high quality high intensity beams continues with two new experiments currently being designed for operation at the AGS; both of these new experiments require slow extracted beam, but with an added requirement of those beams experiments require slow extracted beam, but with an added requirement of those beams experiments and initial tests have been performed. In this report we will describe the beam requirements for the two experiments, and present results of detailed simulations and initial beam tests. | ||
| TUPLT180 | Results of the NASA Space Radiation Laboratory Beam Studies Program at BNL | 1547 |
|
||
| The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The NSRL makes use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. The purpose of the NSRL beam studies program is to develop a clear understanding of the beams delivered to the facility, to fully characterize those beams, and to develop new capabilities in the interest of understanding the radiation environment in space. In this report we will describe the first results from this program. | ||
| TUPLT181 | Results of the First Run of the NASA Space Radiation Laboratory at BNL | 1550 |
|
||
|
The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The results of commissioning of this new facility were reported in [*]. In this report we will describe the results of the first run. The NSRL makes use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. Many modes of operation were explored during the first run, demonstrating all the capabilities designed into the system. Heavy ion intensities from 100 particles per pulse up to $2×109$ particles per pulse were delivered to a large variety of experiments, providing a dose range up to 70 G/min over a 5x5 $cm2$ area. Results presented will include those related to the production of beams that are highly uniform in both the transverse and longitudinal planes of motion [**].
* K.A.Brown, et al, ‘‘Commissioning Results of Slow Extraction of Heavy Ions from the AGS Booster‘‘, Proceedings of the 2003 Particle Accelerator Conference, Portland, OR, 2003** N.Tsoupas, et al, ‘‘Commissioning of the Beam Transfer Line of the Booster Application Facility (BAF) at BNL'', These Proceedings |
||
| TUPLT182 | Measuring Local Gradient and Skew Quadrupole Errors in RHIC IRs | 1553 |
|
||
|
The measurement of local linear errors at RHIC interaction regions using an "action and phase" analysis of difference orbits has already been presented [*]. This paper evaluates the accuracy of this technique using difference orbits that were taken when known gradient errors and skew quadrupole errors were intentionally introduced. It also presents action and phase analysis of simulated orbits when controlled errors are intentionally placed in a RHIC simulation model.
* J. Cardona, S. Peggs, T. Satogata, F. Pilat and V. Ptitsyn,"Determination of Linear and Non Linear Components in RHIC Interaction Regions from difference Orbit Measurements", EPAC 2002, Paris, 2002, p.311-313. |
||
| TUPLT183 | Magnetized Beam Transport in Electron Coolers with Opposing Solenoid Fields | 1556 |
|
||
| To improve cooling capability of electron coolers magnetized beams in strong solenoid fields are used. Too avoid betatron coupling in the ion coupling compensation is required. For the RHIC electron cooler we propose a scheme consisting of two identical solenoids with opposing fields, connected by a quadrupole matching section that preserves the electron beam magnetization. Since the fringe fields of the individual magnets overlap, the matching section can not be designed with standard optics codes. We developed an optimization code based on particle tracking instead. Input for the program are the simulated/measured field maps of the magnets. We demonstrate that the transverse temperature of the electron beam does not increase. | ||
| TUPLT184 | Operational Measurement of Coupling by Skew Quadrupole Modulation | 1559 |
|
||
| The measurements of betatron coupling via skew quadrupole modulation is a new diagnostics technique that has been recently developed and tested at RHIC. By modulating the current of different skew quadrupole families with different frequencies and measuring the resulting eigentunes response with a high resolution phase lock loop (PLL) system, it is possible to determine the projections of the residual coupling coefficients. We report the results of extensive beam studies carried on at RHIC injection, store energy and on the ramp. The capability of measuring coupling on the ramp opens the possibility of continuous coupling corrections during acceleration. | ||
| TUPLT185 | Principle of Skew Quadrupole Modulation to Measure Betatron Coupling | 1562 |
|
||
| The idea of modulating Skew Qudrupoles to measure the ring betatron coupling was put forth by T. Roser. In this paper, analytical solutions for this technique is given. Simulation are also carried out based on RHIC. And other relevent issues concerning this technique's application are also discussed. All of them show this idea of modulating skew qudrupoles to measure the betatron coupling are applicable. | ||
| TUPLT186 | Managing System Parameters for SNS Magnets and Power Supplies | 1565 |
|
||
| The Spallation Neutron Source (SNS), currently under construction at Oak Ridge, Tennessee, is a collaborative effort of six U.S. Department of Energy partner laboratories. With over 312 magnets and 251 power supplies that comprise the beam transport lines and the accumulator ring, it is a challenge to maintain a closed loop on the variable parameters that are integral to these two major systems. This paper addresses the input variables, responsibilities and design parameters used to define the SNS magnet and power supply systems. | ||
| TUPLT187 | SNS Extraction Kicker Power Supply Control | 1568 |
|
||
| There are fourteen PFN power supplies, which will be installed in the SNS Extraction Kicker System. This paper will introduce these fourteen-power supplies arrangement and control schematic. These control instruments and boards are installed into four standard racks. Some of the control boards functions will be list in this paper. Control racks and some control boards pictures will be shown in this paper. | ||
| TUPLT188 | SNS Extraction Kicker Power Supply Manufacture Status | 1571 |
|
||
| There are fourteen PFN power supplies, which will be installed in the SNS Extraction Kicker System. The Pulse Forming Network (PFN) power supplies for the SNS Extraction kicker were designed by Brookhaven. The basic configuration of the PFN is a lumped element Blumlein pulse forming network (BPFN). The PFN and power supply are fabricated by an industrial company. The first article of. PFN and power supply has been manufactured and tested with a dummy load at the company and onsite with the prototype magnet. The PFN has been tested beyond its specification and has met all requirements including rise time, pulse flatness, amplitude and pulse repetition rate. Additional heat runs are scheduled. The transverse coupling impedance of the kicker system with attached PFN has been measured. This paper will report on the SNS Extraction Kicker Power Supply engineering status, and will include output waveforms, impedance measurements, and production projections. | ||
| TUPLT189 | Dipole and Quaqdrupole Sorting for the SNS Ring | 1574 |
|
||
| The Spallation Neutron Source (SNS) accumulator ring is a high intensity ring and must have low uncontrolled losses for hands on maintenance. To achieve these low losses one needs very tight tolerance. These tight tolerances have been achieved through shimming the magnets and sorting. Dipoles are solid core magnets and had very good field quality but magnet to magnet variation were sorted out according to ITF, since all the dipole are powered with one power supply. Typically, sorting is done to minimize linear effects in beam dynamics. Here, sorting of quadrupoles was done according to a scheme which allows to reduce unwanted strength of nonlinear resonances. As a result, the strength of sextupole resonances for our base line tune-box was strongly reduced which was confirmed by a subsequent beam dynamics simulation. | ||
| TUPLT190 | Acceleration of Polarized Beams using Multiple Strong Partial Siberian Snakes | 1577 |
|
||
| Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult since depolarizing spin resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions. Using a 20 - 30 % partial Siberian snake both imperfection and intrinsic resonances can be overcome. Such a strong partial Siberian snake was designed for the Brookhaven AGS using a dual pitch helical superconducting dipole. Multiple strong partial snakes are also discussed for spin matching at beam injection and extraction. | ||
| TUPLT191 | Transverse Optics Improvements for RHIC Run 4 | 1580 |
|
||
| The magnetic settings in RHIC are driven by an online model, and the quality of the resulting lattice functions depend on the correctness of the settings, including knowledge of the magnet transfer-functions. Here we first present the different inputs into the online model, including dipole sextupole compenents, used to set tunes and chromaticities along the ramp. Next, based on an analysis of measured tunes and chromaticities along the fy03 polarized proton ramp, we present predictions for quadrupole transfer-function changes. The changes are implemented for the fy04 Au ramp, and we show the improved model agreement for tunes, and chromaticities along the ramp, and measured transverse phase-advance at store. We also describe model improvements for derived observables like the quality of transverse bump closure and observed luminosity ratios between individual interaction points. | ||
| TUPLT192 | Transition Crossing for the BNL Super Neutrino Beam | 1583 |
|
||
| The super neutrino beam facility proposed at the Brookhaven National Laboratory requires proton beams to cross the transition energy in the AGS to reach 1 MW beam power at top energy. High intensity beams are accelerated at a fast repetition rate. Upon transition crossing, such high intensity bunches of large momentum spreads suffer from strong nonlinear chromatic effects and self-field effects. Using theoretical and experimental methods, we determine the impact of these effects and the effectiveness of transition-jump compensation schemes, and determine the optimum crossing scenario for the super neutrino beam facility. |