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MOOTH1 Overview of High Energy e+e− Factories dynamic-aperture, sextupole, collider, radiation 1
 
  • K. Oide
    KEK, Ibaraki, Japan
  
  Designs of e+e− colliders from the Z-pole and above are introduced. Two projects, CEPC and FCC-ee, are discussed. If we compare their schemes, a partial double ring (CEPC) and a full double ring (FCC-ee), find several important differences that affect the performance. On the other hand, there are a number of similarities in both designs, such as the crab-waist scheme, crossing angle, optimization of the dynamic aperture, etc.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOOTH1  
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MOOTH2 Commissioning of SuperKEKB MMI, vacuum, emittance, detector 4
 
  • Y. Funakoshi
    KEK, Ibaraki, Japan
  
  After 5 years of upgrade work from KEKB, the Phase 1 beam commissioning of SuperKEKB started on Feb. 1st this year and finished at the end of June. In Phase 1, Belle-II detector and the final focus doublet (QCS) were not installed and no beam collision was performed. Missions of the commissioning in Phase 1 were startup of each hardware component, establishment of beam operation software tools, preparation of Belle-II detector, an optics study and tuning without QCS and the detector solenoid magnet and other machine studies. In this talk, achievements in the Phase 1 commissioning are summarized. Also a plan for the Phase 2 commissioning will be given.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOOTH2  
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MOOTH3 Overview on Low Energy Collider luminosity, collider, factory, operation 9
 
  • Q. Qin
    IHEP, Bejing, People's Republic of China
  
  Electron positron colliders cover from low energy machine like Phi factory to very high energy one, Higgs factory, which is still in the way on developing. In this talk, several low energy colliders, DAΦNE as a Phi factory, BEPCII and VEPP-4M as tau-charm factories, and the proposed super charm-tau factories, will be reviewed. The performance and future plans are discussed.
Work supported by the IHEP innovation funds, 2014 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOOTH3  
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MOOTH4 Performance and Perspective of Modern Synchrotron Light Sources emittance, synchrotron, lattice, SRF 17
 
  • D. Einfeld
    ESRF, Grenoble, France
  
  The first synchrotron radiation was used in a so called parasitic mode from high energy machines (1st generation). At the end of the 1970s and the beginning of 1980s accelerators dedicated to the production of synchrotron radiation were built (2nd generations). With the investigation and developments of insertion devices in the middle of 1980, the 3rd generation synchrotron radiation sources were built and emittances down to some nmrad could be reached. At present around 50 Synchrotron Radiation sources are existing around the world. All of these sources reached there the specification (energy, current, emittance, beam stability, etc.) very soon after the commissioning. With the 4th generation, emittances of down to around 100 pmrad should be reached. This is still a factor of 10 away from the requirement of a diffraction limited light source. According to the expertise in designing and operating of synchrotron radiation sources this should be reachable in the future, but only with circumferences of some kilometers like Petra III or PEP-X. Overall the performances and perspective of synchrotron light source are remarkable.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOOTH4  
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MOT3AH2 Higgs Factory Concepts collider, luminosity, emittance, operation 25
 
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  Funding: This work was supported in part by the European Commission under the FP7 Capacities project EuCARD-2, grant agreement 312453.
Designs for future high-energy circular electron-positron colliders are based on both established and novel concepts. An appropriate design will allow these facilities to serve not only as ‘‘Higgs factories'', but also as Z, W and top factories, and, in addition, to become a possible first step to a higher-energy hadron collider. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOT3AH2  
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MOT3AH3 Implementation of Round Colliding Beams Concept at VEPP-2000 collider, luminosity, positron, detector 32
 
  • D.B. Shwartz, D.E. Berkaev, I. Koop, E. Perevedentsev, Yu. A. Rogovsky, P.Yu. Shatunov, Y.M. Shatunov
    BINP SB RAS, Novosibirsk, Russia
  • E. Perevedentsev, Yu. A. Rogovsky, Y.M. Shatunov
    NSU, Novosibirsk, Russia
  
  VEPP-2000 e+e− collider at Budker Institute of Nuclear Physics was commissioned in 2009 and collected data during three runs in whole designed energy range of 160-1000 MeV per beam. The Round Colliding Beams concept was implemented at VEPP-2000 to get a significant enhancement in beam-beam limit. The beam-beam parameter value as high as 0.12 per IP was achieved at intermediate energy. To obtain more intensive beams and achieve target luminosity at top energies the injection chain upgrade was done during 2013-2016. Presently VEPP-2000 is recommissioned and ready to start data taking.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOT3AH3  
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MOT3BH3 Issues in CEPC Pretzel and Partial Double Ring Scheme Design sextupole, lattice, dynamic-aperture, dipole 39
 
  • H. Geng, J. Gao, Q. Qin, D. Wang, Y. Wang, Y. Zhang
    IHEP, Beijing, People's Republic of China
  • F. Su
    Institute of High Energy Physics (IHEP), People's Republic of China
  
  IHEP has proposed a circular electron and positron collider (CEPC) to study the properties of the Higgs boson. In the baseline design, the circumference of CEPC will be taken as 50-70km. The single ring scheme and the partial double ring scheme are now both under study. In the single ring scheme, the electron and positron beam will share the beam pipes, thus a special orbit is needed to avoid the beam colliding at positions except the Interaction Points (IPs). While in the partial double ring scheme, the two beams will be separated into two beam pipes in the parasitic collision positions. This paper will show the latest design of the CEPC lattice, including both the pretzel and partial double ring scheme. Some critical issues that we encountered when designing the lattices will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOT3BH3  
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MOT4H6 Simulations of Polarization Levels and Spin Tune Biases in High Energy Leptons Storage Rings polarization, quadrupole, wiggler, alignment 43
 
  • E. Gianfelice-Wendt
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by Fermi Research Alliance LLC. Under DE-AC02-07CH11359 with the U.S. DOE
Simulations of polarization levels and spin tune biases in high energy leptons storage rings The use of resonant depolarization has been suggested for precise beam energy measurements in the 100 km long Future Circular Collider e+e−. The principle behind resonant depolarization is that a vertically polarized beam excited through an oscillating horizontal magnetic field gets depolarized when the excitation frequency is in a given relationship with the beam energy. In this paper the possibility of self-polarized leptons at 45 and 80 GeV is investigated. Preliminary results of simulations in presence of quadrupole misalignments and beam position monitors (BPMs) errors for a simplified ring are presented. Even in presence of errors a level of polarization useful for energy calibration seems not out of reach. However it is crucial to demonstrate that a energy measurement precision better than 100 KeV can be actually obtained. The last ring layout with 1 mm vertical beta at the IPs has been also considered. The large vertical beta in the IR quadrupoles makes the closed orbit very sensitive to their vertical misalignment and the orbit correction procedure challenging. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOT4H6  
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MOT4H7 Ideas for Siberian Snakes and Spin Rotators in Very High Energy e+e− Rings polarization, solenoid, dipole, synchrotron 47
 
  • S.R. Mane
    Convergent Computing, Shoreham, New York, USA
  
  The high value of the radiated power in synchrotron radiation in very high energy e+e− storage rings presents unique challenges for the design of Siberian Snakes and spin rotators in such machines. This paper presents some ideas which may lead to a feasible design of such devices. The idea is to employ solenoids interleaved with the arc dipoles, to yield a set of noncommuting spin rotations, which can rotate an initially vertical spin to any desired direction. The solenoids should be (approximately) optically transparent, and can be 'spin matched' to the ring using known procedures. Preliminary numerical studies indicate the design may be feasible.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOT4H7  
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TUT1AH1 Issues on IR Design at SuperKEKB sextupole, dynamic-aperture, lattice, beam-beam-effects 49
 
  • Y. Ohnishi
    KEK, Ibaraki, Japan
  
  The design of the interaction region is one of the most important issue in SuperKEKB. The lattice design with the final focus system and the local chromaticity correction as well as the dynamic aperture under the influence of beam-beam interactions are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT1AH1  
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TUT1AH2 Design of Interaction Region and MDI at CEPC detector, background, solenoid, radiation 53
 
  • Q.L. Xiu, J. Gao, X.C. Lou, B. Sha, D. Wang, Y. Wang, H. Zhu
    IHEP, Bejing, People's Republic of China
  
  The CEPC is a proposed circular electron positron collider to study the Higgs boson more accurately. To make sure the machine works well, the compatibility of the machine and the detector is very important. In order to make sure the detector is compatible with the machine, two kinds of problems must be resolved. Firstly, the mutual influence between the machine and the detector must be well studied. It includes the beam induced background, the influence on the beam status from the detector solenoid field and so on. Secondly, the interface between the machine and the detector must be well designed, including the mechanical supporting, the procedure to assemble the interaction region and so on. In this talk, we present the recent progress of the IR design and MDI study of CEPC. The dominant sources of beam induced background have been studied and some preliminary results are obtained. The compensating solenoid and anti-solenoid will be used to suppress the influence on the beam status from the detector solenoid. A global design of the interaction region is undergoing to balance the conflict of performance between the machine and the detector.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT1AH2  
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TUT1AH3 The FCC-ee Interaction Region Magnet Design solenoid, quadrupole, detector, emittance 57
 
  • M. Koratzinos
    DPNC, Genève, Switzerland
  
  The design of the region close to the interaction point of the FCC-ee experiments is especially challenging. The beams collide at an angle (±15 mrad) in the high-field region of the detector solenoid. Moreover, the very low vertical beta' of the machine necessitates that the final focusing quadrupoles have a distance from the IP (L') of around 2 m and therefore are inside the main detector solenoid. The beams should be screened from the effect of the detector magnetic field, and the emittance blow-up due to vertical dispersion in the interaction region should be minimized, while leaving enough space for detector components. Crosstalk between the two final focus quadrupoles, only about 6 cm apart at the tip, should also be eliminated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT1AH3  
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TUT1BH2 Study of Coherent Head-tail Instablility Due to Beam-beam Interaction in Cirular Colliders Based on Crab Waist Scheme simulation, luminosity, damping, emittance 61
 
  • K. Ohmi
    KEK, Ibaraki, Japan
  
  FCC-ee is being studied various collision schemes, head-on and large Piwinski angle/ crab waist schemes. We discuss beam-beam limit in the collision schemes using weak-strong and strong-strong models.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT1BH2  
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TUT2H1 Top-up Injection for a Future Electro-positron Collider injection, luminosity, background, detector 66
 
  • J.T. Seeman
    SLAC, Menlo Park, California, USA
  
  Funding: Work Supported under US DOE/SU Contract DE-AC02-76SF00515.
The schemes for full-energy top-up injection into an e+e− collider will be discussed emphasizing technical issues to be accommodated. The issues include energy stability, energy spread control, transverse emittance reduction, transverse position and angle stability, collimation, background control in the detector, detector blanking of event triggers, and bunch filling strategies. Strategies and observations from PEP-II and KEKB will be included. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT2H1  
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TUT2H2 Injector Linac Upgrade and New RF Gun Development for SuperKEKB gun, cavity, emittance, laser 74
 
  • T. Natsui, D. Satoh, M. Yoshida, R. Zhang, X. Zhou
    KEK, Ibaraki, Japan
  
  The SuperKEKB commissioning has finally started. The final goal of luminosity is 40 times higher than KEKB. The injector upgrade is required to obtain the low emittance and high charge beam corresponding to the short beam life and small injection acceptance of the SuperKEKB ring. In the injector linac, several new instruments have been installed. Flux Concentrator (FC) was developed for high charge positron beam production. The target bunch charge of positron beam is 4 nC. The new damping ring will be used for positron beam to reduce beam emittance to 10 mm-mrad. However, electron beam must be reached to 20 mm-mrad normalized emittance at 5 nC beam charge without damping ring. Thermionic gun was used for KEKB injector and it was able to generate enough beam charge. However, its emittance is too large. Therefor we developed photo cathode S-band RF gun. This new RF gun has unique accelerating cavity which called quasi-travelling wave side coupled cavity. Laser system for this photo cathode has been also developed. The laser system is constructed with Yb:YAG thin disk for high power and pulse shaping. I will illustrate the RF gun, laser system and several new injector linac systems.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT2H2  
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TUT2H3 Design study of CEPC Booster dynamic-aperture, dipole, sextupole, wiggler 79
 
  • T.J. Bian, X. Cui, J. Gao, B. Sha, D. Wang, Y. Wang, M. Xiao, C. Zhang
    IHEP, Beijing, People's Republic of China
  • Y. Cai
    SLAC, Menlo Park, California, USA
  • M. Koratzinos
    DPNC, Genève, Switzerland
  • F. Su
    Institute of High Energy Physics (IHEP), People's Republic of China
  
  Funding: Work supported by National Natural Science Foundation of China, Grant No. NSFC 11575218 and No. 11505198
CEPC is next generation circular collider proposed by China. The design of the full energy booster ring of the CEPC is especially challenging. The ejected beam energy is 120GeV, but the injected beam only 6GeV. In a conventional approach, the low magnetic field of the main dipole magnets creates problems. we have two ways to solve this problem, Firstly, we propose to operate the booster ring as a large wiggler at low beam energy and as a normal ring at high energies to avoid the problem of very low dipole magnet fields. Secondly, we implement the orbit correction and correct the earth field to make booster work. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT2H3  
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TUT2H4 Top-up Injection Schemes for HEPS injection, cavity, kicker, operation 85
 
  • Z. Duan, J. Chen, Y. Jiao, Y.M. Peng, Q.Y. Wang, G. Xu, P. Zhang
    IHEP, Beijing, People's Republic of China
  
  Funding: Natural Science Foundation of China (No.11605212)
Top-up injection has become standard mode of operation for most third generation light sources, and has also been suc- cesfully applied in electron-positron circular colliders like KEKB and PEP-II. For next generation ultra-low emittance storage rings approaching the diffraction limit of X-rays, take the High Energy Photon Source (HEPS) for example, top-up injection is a basic requirement but non-trivial to im- plement. The very small dynamic aperture is insufficient for traditional off-axis injection scheme, instead, a novel on-axis injection scheme was recently proposed for HEPS, based on RF gymnastics of a double-frequency RF system. This paper will describe the physical mechanism of this scheme, related RF issues, and the implications for top-up injection. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT2H4  
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TUT2H5 Towards a Preliminary FCC-ee Injector Design emittance, linac, positron, damping 90
 
  • S. Ogur, Y. Papaphilippou, F. Zimmermann
    CERN, Geneva, Switzerland
  • A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov
    BINP SB RAS, Novosibirsk, Russia
  • K. Furukawa, N. Iida, F. Miyahara, K. Oide
    KEK, Ibaraki, Japan
  
  The Future Circular Collider-ee aims to get high luminosity which mainly relies upon high charge and low geometric emittance in the collider. The FCC-ee is a future project of CERN to operate as Z, W, H and tt factories with varying energies between 45.6 to 175 GeV. Among those, the total charge requirement is peaked for Z-operation (i.e. 91500 bunches of electron and positron with 3.3·1010 particles per bunch) meanwhile this mode targets the smallest geometric emittance in the Collider. To reach the goal, the normal conducting S-band Linac has been designed to accelerate 4·1010 particles in a bunch to 6 GeV and send two bunches per RF pulse within a repetition of 100 Hz. The FCC-ee positrons will also be created inside the linac at 4.46 GeV and accelerated to 1.54 GeV. These positrons are damped at the designed Damping Ring at that energy, and then transferred back to the Linac to meet the same characteristics of electrons. Therefore, in this paper, we'd like to discuss the transmission and robustness of the Linac and the dynamic aperture of the Damping Ring which has to be large enough to accept the incoming beam and cover the probable shrink due to the misalignments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT2H5  
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TUT2H6 Electron Sources and Polarization gun, cathode, electron, SRF 94
 
  • R. Xiang, J. Teichert
    HZDR, Dresden, Germany
  
  Funding: Supported by the European Community under the FP7 programme (EuCARD-2 and LA3NET) and by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
In this presentation the present electron sources and the relevant issues will be discussed. For the electron positron colliders and accelerator based light sources, the electron gun and injector design, are arguably the most critical part. There are a variety of electron source designs: DC guns, normal-conducting RF guns, superconducting RF gun and hybrid guns. All variants have their own ad-vantages and difficulties. We will overview the typical sources around the world, and compare their advantages and main challenges. The polarization production will also be discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT2H6  
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TUT3AH1 Collective Effects Issues for FCC-ee impedance, wakefield, radiation, synchrotron 100
 
  • M. Migliorati
    University of Rome La Sapienza, Rome, Italy
  • E. Belli
    CERN, Geneva, Switzerland
  • G. Castorina, B. Spataro, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • S. Persichelli
    LBNL, Berkeley, California, USA
  
  The Future Circular Collider study, hosted by CERN to design post-LHC particle accelerator options in a worldwide context, represents a great challenge under several aspects, which require R&D on beam dynamics and new technologies. One very critical point is represented by collective effects, generated by the interaction of the beam with self-induced electromagnetic fields, called wake fields, which could produce beam instabilities, thus reducing the machines performance and limiting the maximum stored current. It is therefore very important to be able to predict these effects and to study in detail potential solutions to counteract them. In this paper the resistive wall and some other important geometrical sources of impedance for the FCC electron-positron accelerator are identified and evaluated, and their impact on the beam dynamics, which could lead to unwanted instabilities, is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3AH1  
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TUT3AH2 Instability Issues in CEPC impedance, cavity, damping, coupling 108
 
  • N. Wang, W. Chou, J. Gao, D.J. Gong, J. He, Q. Qin, Y.S. Sun, D. Wang, Y. Wang, G. Xu, Y. Zhang, H.J. Zheng
    IHEP, Beijing, People's Republic of China
  • K. Ohmi, D. Zhou
    KEK, Ibaraki, Japan
  
  The CEPC is a high energy circular electron-positron collider under design. Large bunch population is required to achieve the design luminosity. Instabilities driven by the coupling impedance are possible limitations for reaching high machine performance. An updated impedance model, including the resistive wall and the main vacuum components, has been obtained for the main ring. Based on the impedance model, the collective instability issues of the beam with the partial-double ring design are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3AH2  
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TUT3AH3 Beam-based Impedance Measurement Techniques impedance, vacuum, simulation, damping 112
 
  • V.V. Smaluk
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by DOE under contract No.DE-AC02- 98CH10886
Characterization of a vacuum chamber impedance is necessary to estimate stability conditions of a particle beam motion, to find a limit of the beam intensity and characteristic times of single-bunch and multi-bunch instabilities. For new accelerator projects, minimization of the vacuum chamber impedance is now the mandatory requirement. For an accelerator in operation, the impedance can be measured experimentally using various beam-based techniques. The beam-impedance interaction manifests itself in measurable beam parameters, such as betatron tunes, closed orbit, growth rates of instabilities, bunch length and synchronous phase. The beam-based techniques developed for measurement of the longitudinal and transverse impedance are discussed, including theoretical basics and experimental results. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3AH3  
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TUT3AH5 Electron Cloud and Ion Effects and Their Mitigation in FCC-ee electron, feedback, simulation, damping 120
 
  • K. Ohmi, H. Fukuma, M. Tobiyama
    KEK, Ibaraki, Japan
  
  Electron cloud and fast-ion instabilities are serious issues for colliders operated with high current and many bunches. We discuss the instabilities in FCC-ee/hh based on simulations and experiences of KEKB/SuperKEKB.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3AH5  
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TUT3AH6 Electron Cloud at SuperKEKB electron, permanent-magnet, solenoid, operation 125
 
  • H. Fukuma, K. Ohmi, Y. Suetsugu, M. Tobiyama
    KEK, Ibaraki, Japan
  
  Several countermeasures such as ante-chambers, TiN coating, clearing electrodes, grooved structure and so on, have been taken to mitigate the electron cloud effects in the SuperKEKB positron ring. During phase 1 operation of SuperKEKB, which continued from this February to June, the electron cloud effects such as beam size blow-up, non-linear pressure increase, betatron tune shift along a bunch train and transverse coupled bunch instability were observed. Permanent magnets attached at bellows that generate longitudinal magnetic field in vacuum chambers were effective to reduce the electron cloud. This talk will cover following subjects about the electron cloud at SuperKEKB, 1) mitigation methods against the electron cloud, 2) observation of the electron cloud effects in phase 1 operation and 3) plan of further reduction of the electron cloud toward phase 2 operation which will start in the late FY2017.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3AH6  
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TUT3AH7 Electron Cloud and Collective Effects in the Interaction Region of FCC-ee electron, impedance, simulation, quadrupole 130
 
  • E. Belli, G. Rumolo
    CERN, Geneva, Switzerland
  • E. Belli
    University of Rome "La Sapienza", Rome, Italy
  • E. Belli
    INFN-Roma, Roma, Italy
  • M. Migliorati
    University of Rome La Sapienza, Rome, Italy
  • M. Migliorati
    INFN-Roma1, Rome, Italy
  
  The FCC-ee is an e+e− circular collider designed to accommodate four different experiments in a beam energy range from 91 to 350 GeV and is a part of the Future Circular Collider (FCC) project at CERN. One of the most critical aspects of this new very challenging machine regards the collective effects which can produce instabilities, thus limiting the accelerator operation and reducing its performance. The following studies are focused on the Interaction Region of the machine. This talk will present preliminary simulation results of the power loss due to the wake fields generated by the electromagnetic interaction of the beam with the vacuum chamber. A preliminary estimation of the electron cloud build-up is also reported, whose effects have been recognized as one of the main limitations for the Large Hadron Collider at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3AH7  
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TUT3AH9 Feedback Systems for FCC-ee feedback, kicker, damping, pick-up 136
 
  • A. Drago
    INFN/LNF, Frascati (Roma), Italy
  
  In this paper, some preliminary considerations on the feedback systems for FCC-ee are developed. Bunch-by-bunch feedback systems have been de-signed in the last years for other e+/e− colliders like PEP-II, KEKB, DAΦNE, SuperB and SuperKEKB. In all these cases, similar approaches have been implement-ed, even if some design variations have been suitable or necessary for different reasons. Bunch-by-bunch feedback systems are based on the concept that the barycenter of each bunch moves with harmonic motion around the equilibrium point in three planes (L, H, V). The feedback copes with the forcing excitation by producing damping correction for each individual bunch. This is possible managing every single bunch by a dedicated processing channel in real time. For FCC-ee the very high number of stored bunches re-quires much more power in terms of processing capa-bility for the feedback systems. Ring length (100 Km) and very low fractional tunes must be also considered requiring for a more effective strategy in the feedback system design.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3AH9  
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TUT3BH2 Optics Correction and Low Emittance Tuning at the Phase 1 commissioning of SuperKEKB sextupole, emittance, optics, coupling 143
 
  • Y. Ohnishi, Y. Funakoshi, H. Koiso, A. Morita, K. Oide, H. Sugimoto
    KEK, Ibaraki, Japan
  
  The SuperKEKB collider has finally come to the first commissioning, Phase 1 without the final focus system and before Belle II detector roll-in. In order to accomplish a extremely high luminosity of 8x1035 cm-2s-1, the nano-beam scheme is adopted. Since the vertical emittance is one of keys in this scheme, optics corrections for low emittance tuning are applied. The non-interleaved sextupole scheme is utilized in the arc section. Skew quadrupole-like corrector is equipped for each sextupole. These skew quadrupole-like correctors can correct both X-Y coupling and physical vertical dispersions which induce the vertical emittance. Beta function and physical horizontal dispersion are corrected by fudge factors of quadrupoles and/or horizontal orbit bumps at the sextupoles. Overall optics performance as well as the strategy of low emittance tuning is also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3BH2  
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TUT3BH3 Luminosity Tuning at KEKB luminosity, injection, operation, coupling 147
 
  • Y. Funakoshi
    KEK, Ibaraki, Japan
  
  KEKB achieved the world's highest luminosity. One of the key issues for the high luminosity at KEKB was a luminosity tuning which was done almost every time even during the physics run to suppress the beam-beam blowup. In this talk, those experiences are summarized. Some experiences of the luminosity tuning at TRISTAN will also mentioned.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3BH3  
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TUT3BH4 Coupling and Dispersion Correction for the Tolerance Study in FCC-ee coupling, emittance, quadrupole, lattice 151
 
  • S. Aumon, A. Doblhammer, B. Härer, B.J. Holzer
    CERN, Geneva, Switzerland
  • B. Härer
    KIT, Karlsruhe, Germany
  • K. Oide
    KEK, Ibaraki, Japan
  
  The FCC-ee study is investigating the design of a 100 km e+/e− circular collider for precision measurements and rare decay observations in the range of 90 to 350 GeV center of mass energy with luminosities in the order of 1035 cm-2s-1. In order to reach such performances, an extreme focusing of the beam is required in the interaction regions with a low vertical beta function of 2 mm at the IP. Moreover, the FCC-ee physics program requires very low emittances never achieved in a collider with 1.3 nm for εx and 2 pm for εy at 175~GeV, reducing the coupling ratio to around 2/1000. With such requirements, any field errors and sources of coupling will introduce spurious vertical dispersion which degrades emittances, limiting the luminosity of the machine. This study describes the status of the tolerance study and the impact of errors that will affect the vertical emittance. In order to preserve the FCC-ee performances, in particular εy, a challenging correction scheme based on dispersion free steering and linear coupling correction is proposed to keep the coupling and the vertical emittance as low as possible.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT3BH4  
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WET1H1 Beam Instrumentation Needs for a Future Electron-Positron Collider Based on PEP-II Observations luminosity, vacuum, feedback, instrumentation 157
 
  • J.T. Seeman
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by US DOE/SU Contract DE-AC02-76SF00515.
Future e+e− colliders will operate with many bunches, short bunch lengths, small emittances, high currents, and small interaction point betas. The stability of the colliding beams with these characteristics will depend on detailed, high precision, and continuous measurements. The various beam measurement requirements and techniques will be discussed using PEP-II observations as a starting point. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET1H1  
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WET1H3 Beam Instrumentation in SuperKEKB feedback, detector, kicker, operation 164
 
  • H. Fukuma
    KEK, Ibaraki, Japan
  
  SuperKEKB is an upgraded collider of the KEK B-factory (KEKB). Its phase 1 operation has just finished in this June. A BPM system consists of super heterodyne detectors, turn by turn log-ratio detectors with fast gates and detectors for the orbit feedback to maintain stable collision. New X-ray beam profile monitors with multi-slit masks are installed. The bunch-by-bunch feedback system is upgraded using low noise frontend electronics and new 12 bits iGp digital filters. A status of instrumentations of SuperKEKB will be given in this talk.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET1H3  
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WET1H4 Measurement of Beam Polarization and Beam Energy in One Device electron, polarization, photon, laser 168
 
  • N.Yu. Muchnoi
    BINP SB RAS, Novosibirsk, Russia
  
  Funding: Russian Science Foundation N 14-50-00080
Electron beam interaction with the monochromatic laser radiation produces scattered photons and electrons due to the Compton effect. Both types of scattered particles carry the information about the polarisation (if any) and the energy of initial electrons in the beam. This report is focused on the properties of the scattered electrons. After a bending magnet these electrons leave the beam and their X-Y space distribution is supposed to be measured by the 2D pixel detector. We show that if the electron beam vertical emittance is sufficiently small, the shape of this distribution is an ellipse. Measurement of the length of the X-axis of this ellipse allow to calibrate accurately the bending field integral seen by the beam. The distribution of the electrons within the ellipse depends on the initial beam polarisation, allowing to measure its degree and direction. So we propose a universal Compton polarimeter with a unique feature of precise calibration of the LEP-style beam energy spectrometer. The approach is thought to be useful for the future high-energy e+/e− colliders, while the feasibility tests need to be performed on existing accelerators. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET1H4  
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WET2H4 New Cavity Techniques and Future Prospects cavity, niobium, superconducting-cavity, SRF 173
 
  • P. Sha
    Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
  • J.Y. Zhai
    IHEP, Beijing, People's Republic of China
  
  Funding: This study was supported by National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400) and National Natural Science Foundation of China (Grant NO.: 11505197)
In the recent decades, Superconducting cavities have been widely used to accelerate electron, positron, and ions. Most SRF cavities are made from bulk niobi-um till now, which has developed fast in the past years and is hard to advance more. Take 1.3 GHz 9-cell cavi-ty for example, the quality factor (Q) can keep above 1010 when the accelerating field (Eacc) reach 40 MV/m, which nearly touch the theoretical limitation of Q and Eacc for bulk niobium. For large superconducting accelerators in future (FCC, CEPC, etc), Q and Eacc should be increased significantly compared to now, which can reduce the cryogenic power and use fewer cavities. So new cavity material and techniques are being studied at accelerator laboratories, while Nitro-gen doping (N-doping) and Nb3Sn have developed quickly and been paid attention to mostly [1]. N-doping can increase Q by one time for 1.3 GHz 9-cell cavity, which have been adopted by Linac Coherent Light Source II (LCLS-II) at SLAC [2].
[1],Alexander Romanenko, Bulk Nb Based SRF Technology, FCC Week 2016.
[2],Camille M Ginsburg, LCLS-II Cryomodules at FNAL & JLAB, TTC 2016. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET2H4  
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WET2H7 LLRF Controls Including Gap Transients at KEKB and Plans for SuperKEKB cavity, controls, LLRF, simulation 177
 
  • T. Kobayashi, K. Akai
    KEK, Ibaraki, Japan
  
  Features of LLRF control systems in KEKB and SuperKEKB will be reviewed, and the evaluation of the bunch gap transient effect on beam phase will be presented for SuperKEKB. The RF systems of KEKB are being reinforced to handle triple as large beam power for upgrade to SuperKEKB. Furthermore, a new LLRF control system, which is based on a recent digital control technique, has been developed. For nine RF stations, among a total of thirty, the LLRF control system has been replaced with new ones. They were worked successfully in the Phase-1 commissioning. Bunch phase shift along the bunch train due to a bunch gap transient is a concern. In KEKB operation, a rapid phase change was observed at the leading part of the train, which was not predicted. Our new simulation study clarified that the rapid phase change is caused by a transient loading in the three-cavity system of ARES. And the new simulation shows that the phase change will be much large in SuperKEKB. The main issue is the difference in beam phase change between the two rings for the asymmetry colliding. The measures by means of mitigation of the relative beam phase difference between the two rings will be also suggested.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET2H7  
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WET3AH2 High Efficiency Klystron Development for Particle Accelerators klystron, electron, cavity, bunching 185
 
  • D.A. Constable
    Lancaster University, Lancaster, United Kingdom
  • A.Yu. Baikov
    MFUA, Moscow, Russia
  • G. Burt, V.C.R. Hill, C. Lingwood
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • I.A. Guzilov
    JSC Vacuum Devices Basic Technologies, Moscow, Russia
  • A. Jensen
    SLAC, Menlo Park, California, USA
  • R.D. Kowalczyk
    L-3, Williamsport, Pennsylvania, USA
  • R. Marchesin
    TED, Velizy, France
  • C. Marrelli
    ESS, Lund, Sweden
  • I. Syratchev
    CERN, Geneva, Switzerland
  
  Upcoming large scale particle accelerators, such as the Future Circular Collider (FCC), the Compact Linear Collider (CLIC) and the International Linear Collider (ILC) are expected to require RF drive on the order of 100 MW. Therefore, efforts to improve the efficiency of the specific RF source is of significant interest to the particle accelerator community. Klystrons are an attractive choice as the RF source, with the current state of the art tubes offering efficiencies up to 70%. The High Efficiency International Klystron Activity (HEIKA) collaboration seeks to improve upon this by considering novel methods of electron bunching. Such methods include the core oscillation method (COM), the bunching-alignment-collection (BAC) method, as well as the use of harmonic cavities. The theory behind these bunching methods will be discussed, along with their suitability for specific particle accelerators. In addition, results from numerical simulations predicting klystrons with efficiencies larger than 80% will be presented. Early experimental testing of tubes employing the BAC method will also be presented, demonstrating the efficiency improvements that the scheme offers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET3AH2  
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WET3AH3 Extraction Line and Beam Dump for the Future Electron Positron Circular Collider kicker, extraction, collider, electron 188
 
  • A. Apyan
    ANSL, Yerevan, Armenia
  • K. Oide
    KEK, Ibaraki, Japan
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  The conceptual design of an extraction line and beam dump for the future electron positron circular collider is presented. The proposed extraction line, consisting of abort kicker system, spoilers and beam diagnostics apparatus transports the electron and positron beams to the main beam dumps. The beam must be spread over a large surface in order not to damage the beam dump and the window, which separates the ring from the dump. The extraction line redistributes bunches at different locations on the face of beam dump. Monte Carlo simulations using FLUKA have been performed to estimate the distribution of energy deposition on the window and beam dump to find the optimal absorber and its dimensions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET3AH3  
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WET3BH1 Improvement of Efficiency of Klystron to Apply the CPD Method klystron, electron, cavity, radiation 192
 
  • K. Watanabe
    KEK, Ibaraki, Japan
  
  A high power RF system for the particle accelerators needs large electrical power in the operation. An improvement of efficiency is also always required as a technology component for the energy saving. To improve efficiency of a high-power source, the CPD (Collector Potential Depression) method already was applied a Gyrotron to recovery the electrical energy form the collector loss. The CPD is an energy-saving scheme that recovers the kinetic energy of the spent electrons after generating rf power. A CPD klystron (E37703 CPD) was fabricated at 2013, to recycle an existing klystron of Toshiba E3786. The purpose of our study is to demonstrate the proof-of-principle of the CPD method to apply a klystron. A plane of R&D of CPD klystron at KEK will be reported in this meeting.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-WET3BH1  
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THS1H1 Summary of Design Concepts collider, luminosity, factory, hadron 195
 
  • F. Zimmermann, R.W. Aßmann
    CERN, Geneva, Switzerland
  • A.P. Blondel
    DPNC, Genève, Switzerland
  
  This paper summarizes the session on design concepts at the ICFA workshop on future circular electron-positron factories "eeFACT2016".  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS1H1  
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THS1H2 Summary of Optics Issues dynamic-aperture, optics, sextupole, lattice 199
 
  • K. Oide
    KEK, Ibaraki, Japan
  
  Summary of Optics Issues  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS1H2  
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THS1H4 Summary of IR and MDI Session quadrupole, detector, solenoid, background 200
 
  • Y. Funakoshi
    KEK, Ibaraki, Japan
  
  A brief summary of talks in IR and MDI session is given. Also features and issues on the IR design in the future colliders are summarized.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS1H4  
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THS1H5 Summary Beam-beam Session, eeFACT2016 Workshop simulation, beam-beam-effects, resonance, collider 203
 
  • A. Chao
    SLAC, Menlo Park, California, USA
  
  There are two talks in the beam-beam session. But beam-beam is an issue that permeates in several other sessions. So in this summary I have taken the liberty to include some materials extracted also from other sessions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS1H5  
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THS1H6 Summary of Injector and Beam Injection injection, gun, collider, booster 206
 
  • J.T. Seeman
    SLAC, Menlo Park, California, USA
  
  Summary of Injector and Beam Injection: This summary covers the Injection and Sources Session of the e+e- Factories Workshop 2016, which had six presentations. Here we discuss the goals for top-up injection for a collider and their sources and then covers the highlights, discussion topics, and future plans for each presentation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS1H6  
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THS2H1 Summary of Impedance Issues and Beam Instabilities electron, impedance, feedback, wakefield 210
 
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  Funding: This work was supported in part by the European Commission under the FP7 Capacities project EuCARD-2, grant agreement 312453.
This paper summarizes the session on impedance issues and beam instabilities at the ICFA workshop on future circular electron-positron factories "eeFACT2016" held at the Cockcroft Institute, Daresbury, from 24 to 27 October 2016. This session also covered active beam stabilization by feedback systems. Beam-beam effects and coherent beam-beam instabilities were addressed separately and, therefore, are not included here. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS2H1  
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THS2H2 Summary of Machine Tuning Session luminosity, optics, emittance, coupling 216
 
  • M.E. Biagini
    INFN/LNF, Frascati (Roma), Italy
  
  This paper summarizes the work presented at the Machine Tuning session on the low emittance tuning for low emittance lattices and luminosity tuning at colliders.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS2H2  
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THS2H3 Summary of Beam Instrumentation and Beam Diagnostics Session instrumentation, electron, polarization, feedback 220
 
  • H. Fukuma
    KEK, Ibaraki, Japan
  
  This report is a summary of the beam instrumentation and beam diagnostics session of the eeFACT2016 workshop.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS2H3  
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THS2H4 SRF Working Group Summary cavity, HOM, SRF, damping 223
 
  • R.A. Rimmer
    JLab, Newport News, Virginia, USA
  
  Summary of Superconducting RF: This working group focused on the status and challenges of superconducting Radio Frequency (SRF) cavities and systems for present and future high luminosity lepton colliders, the so-called 'factories'. Submissions covered the state of the art of SRF cavity designs, HOM damping, high power couplers, operational experiences and the needs of future colliders. Active work on similar SRF systems for the electron complex of a future electron ion collider (EIC) was presented. Much of this technology is also useful for next generation high brightness light sources and other applications.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS2H4  
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THS2H6 Summary: Joint Session of Other Technologies and Energy Efficiency klystron, collider, plasma, SRF 231
 
  • W. Chou
    Fermilab, Batavia, Illinois, USA
  
  This paper summarizes the presentations and discussions at the joint session of 'Other Technologies' and 'Energy Efficiency.' It also highlights several key issues for R&D in these fields.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-THS2H6  
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