IPAC2019 - List of Keywords (collider)

Paper	Title	Other Keywords	Page
MOYPLM3	Progress with the High Luminosity LHC Project at CERN	luminosity, cavity, operation, quadrupole	17
	L. Rossi, O.S. Brüning CERN, Geneva, Switzerland
	The High Luminosity LHC (HL-LHC) project aims at upgrading the LHC by increasing the peak luminosity by a factor five, to allow to collect 3000 fb-1 for ATLAS and CMS experiments, each, which is ten times more than what is foreseen in the LHC. The upgrade is based on multiple factors. One factor is doubling the beam current, also thanks to the injector upgrade (LIU) project, and another one is operation in levelling mode. The most critical upgrade is the deploying of a stronger inner quadrupole triplet in the low-beta insertions with more than twice-larger aperture w.r.t. present LHC triplet, thanks to the use of Nb₃Sn superconductor, a world first for accelerators, with almost 12 T peak field in the coils. The novel concept of ATS optics allows to utilise the increased aperture efficiently by generating β^* values 3 to 4 times below the nominal values of the LHC. We will make use of compact crab cavities for hadrons (also a novelty in accelerators) to allow almost head-on collisions despite the larger crossing angle. We are developing new collimator insertions in the dispersion suppressor region to handle the losses in the cold part of the machine (the beam halo stores 30 MJ) thanks to the use of a few 11 T dipoles based on Nb₃Sn technology. We also aim at reducing drastically the impedance contribution of collimators by utilizing new materials and coating techniques. Many other technologies are developed for HL-LHC like new SC links of 100 kA: HL-LHC is critical as a technology turning point for HEP colliders as it is for Physics reach. The technologies developed for HL-LHC, namely (but not only) the high field superconducting magnets, are critical for the post-LHC hadron collider, like a High Energy LHC or the 100 km Future Circular Collider
	Slides MOYPLM3 [21.679 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOYPLM3
About •	paper received ※ 19 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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MOZPLS2	Ion Collider Precision Measurements With Different Species	target, operation, electron, experiment	28
	G.J. Marr, E.N. Beebe, I. Blackler, W. Christie, K.A. Drees, P.S. Dyer, A.V. Fedotov, W. Fischer, C.J. Gardner, H. Huang, T. Kanesue, N.A. Kling, V. Litvinenko, C. Liu, Y. Luo, D. Maffei, B. Martin, A. Marusic, K. Mernick, M.G. Minty, C. Naylor, M. Okamura, I. Pinayev, G. Robert-Demolaize, T. Roser, P. Sampson, V. Schoefer, T.C. Shrey, D. Steski, P. Thieberger, J.E. Tuozzolo, K. Zeno, I.Y. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Precedent to electron cooling commissioning and collisions of Gold at various energies at RHIC in 2018, the STAR experiment desired an exploration of the chiral magnetic effect in the quark gluon plasma (QGP) with an isobar run, utilizing Ruthenium and Zirconium. Colliding Zr-96 with Zr-96 and Ru-96 with Ru-96 create the same QGP but in a different magnetic field due to the different charges of the Zr (Z=40) and Ru (Z=44) ions. Since the charge difference is only 10%, the experimental program requires exacting store conditions for both ions. These systematic error concerns presented new challenges for the Collider, including frequent reconfiguration of the Collider for the different ion species, and maintaining level amounts of instantaneous and integrated luminosity between two species. Moreover, making beams of Zr-96 and Ru-96 is challenging since the natural abundances of these isotopes are low. Creating viable enriched source material for Zr-96 required assistance processing from RIKEN, while Ru-96 was provided by a new enrichment facility under commissioning at Oak Ridge National Laboratory.
	Slides MOZPLS2 [4.758 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOZPLS2
About •	paper received ※ 11 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOZZPLS2	Positron Driven Muon Source for a Muon Collider: Recent Developments	target, emittance, damping, positron	49
	M.E. Biagini, M. Antonelli, O.R. Blanco-García, M. Boscolo, A. Ciarma, A. Giribono, S. Guiducci, C. Vaccarezza, A. Variola INFN/LNF, Frascati, Italy A. Bacci INFN-Milano, Milano, Italy M. Bauce, F. Collamati INFN-Roma1, Rome, Italy G. Cesarini INFN-Roma, Roma, Italy I. Chaikovska, R. Chehab LAL, Orsay, France S.M. Liuzzo, P. Raimondi ESRF, Grenoble, France D. Lucchesi Univ. degli Studi di Padova, Padova, Italy N. Pastrone INFN-Torino, Torino, Italy
	The design of a future multi-TeV muon collider needs new ideas to overcome the technological challenges related to muon production, cooling, accumulation and acceleration. The Low Emittance Muon Accelerator (LEMMA) concept ,* presents in this paper an upgraded layout of a positron driven muon source. The positron beam, stored in a ring with high energy acceptance and low emittance, is extracted and driven in a push-pull configuration to a multi-target system, to produce muon pairs at threshold on the target’s electrons. This solution alleviates the issues related to the power deposited and the integrated Peak Energy Density Deposition on the targets. Muons produced in the multi-target system will then be accumulated in many parallel rings before acceleration and injection in the collider. A special multi-target line lattice has been designed to cope with the focusing of both the positron and muon beams. Studies on the number, material and thickness of the targets have been carried out. A general layout of the overall scheme and a description is presented, as well as plans for future R&D. * M. Antonelli, P. Raimondi, INFN-13-22/LNF, 2013 ** M. Boscolo, M. Antonelli, O.R. Blanco-Garcia, S. Guiducci, S. Liuzzo, P. Raimondi, F. Collamati, Phys. Rev. Accel. Beams, vol. 21, p. 061005, 2018
	Slides MOZZPLS2 [4.360 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOZZPLS2
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW051	Diffusion Map Analysis in High Energy Storage Ring Based e⁺/e⁻ Collider	dynamic-aperture, radiation, synchrotron-radiation, synchrotron	203
	J. Wu, Q. Qin, Y. Zhang IHEP, Beijing, People’s Republic of China J. Wu, Y. Zhang University of Chinese Academy of Sciences, Beijing, People’s Republic of China
	Funding: Project 11775238 supported by NSFC In a very high energy e⁺/e⁻ storage ring collider, e.g. Circular Electron Positron Collider (CEPC), the dynamic aperture is limited by the strong synchrotron radiation especially in the vertical direction. Some tracking results also shows that the beam lifetime does not correspond well to the dynamic aperture. Here we develop a method called diffusion map analysis, aiming to describe the beam distribution diffusion in transverse amplitude space by tracking less turns. The diffusion may come from quantum fluctuation of SR, beamstrahlung effect and nonlinearity. Comparing cases with different configuration of sextupoles, the diffusion map analysis presents good consistency with beam lifetime that needs much more turns of tracking. Constraints based on the diffusion map is applied to our dynamic aperture optimization, which could help us achieve enough long beam lifetime.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW051
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW068	Crosstalk of Beam-Beam Effect and Longitudinal Impedance at CEPC	impedance, simulation, luminosity, factory	247
	Y. Zhang, N. Wang, C.H. Yu IHEP, Beijing, People’s Republic of China C.T. Lin University of Chinese Academy of Sciences, Beijing, People’s Republic of China
	Funding: Project 11775238 supported by NSFC In conventional e⁺e⁻ storage ring colliders, we only use lengthend bunch length in beam-beam simulation instead of considering impedance directly. It is no problem since the longitudinal dynamics is not sensitive to beam-beam interaction. But it is different since the bunch will also be lengthend during beam-beam interaction by beamstrahlung effect. It is very natural and more self-consistent to consider the longitudinal impedance in the beam-beam simulation. The simulation shows that the working point region of stable collision is slightly shifted by the longitudinal impedance. It is found that the vertical coherent oscillation may decreases the beam-beam limit with impedance at some working point.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW068
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW071	Resistive Wall Effects in the CLIC Beam Delivery System	luminosity, wakefield, vacuum, feedback	258
	D. Arominski, A. Latina, D. Schulte CERN, Meyrin, Switzerland
	Resistive wall wakefields are an important issue to study for future linear colliders. Wakefields in the Beam Delivery System (BDS) might cause severe multi-bunch effects, leading to beam quality and luminosity losses. The resistive wall effects depend on the beam pipe apertures and materials, which are optimised to limit the impact on the beam. This paper presents a study of this problem for the 380 GeV and 3 TeV beam parameters and optics of the Compact Linear Collider’s BDS. First, the optimisation of the beam pipe apertures to limit the impact of resistive wall effect on the beam quality is shown, then the luminosity and its quality are presented. Finally, the proposed design parameters are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW071
About •	paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW081	Measurements of Stray Magnetic Fields at CERN for CLIC	klystron, site, proton, dipole	289
	C. Gohil, N. Blaskovic Kraljevic, D. Schulte CERN, Meyrin, Switzerland P. Burrows JAI, Oxford, United Kingdom B. Heilig MFGI, Budapest, Hungary
	Simulations have shown that the Compact Linear Collider (CLIC) is sensitive to external dynamic magnetic fields (stray fields) to the nT level. Magnetic fields are not typically measured to this precision at CERN. Past measurements of the background magnetic field at CERN are limited. In this paper new measurements are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW081
About •	paper received ※ 01 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW082	Mitigation of Stray Magnetic Field Effects in CLIC with Passive Shielding	shielding, feedback, simulation, hadron	293
	C. Gohil, N. Blaskovic Kraljevic, D. Schulte CERN, Meyrin, Switzerland P. Burrows JAI, Oxford, United Kingdom
	Simulations have shown the Compact Linear Collider (CLIC) is sensitive to external dynamic magnetic fields (stray fields) to the nT level. Due to these extremely tight tolerances, mitigation techniques will be required to prevent performance loss. A passive shielding technique is envisaged as a potential solution. A model for passive shielding is presented along with calculations of its transfer function. Measurements of the transfer function of a promising material (mu-metal) that can be used for passive shielding are presented. The validity of passive shielding models in small amplitude magnetic fields is also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW082
About •	paper received ※ 01 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW084	Beam Loading Compensation for the Future Circular Hadron-Hadron Collider (FCC-hh)	cavity, beam-loading, hadron, impedance	301
	I. Karpov, P. Baudrenghien CERN, Meyrin, Switzerland
	The power consumption of the rf system can be minimised by optimising the cavity detuning and the loaded quality factor. In high-current accelerators, the presence of gaps in the filling results in a modulation of the cavity voltage along the ring (transient beam loading) and as a consequence a spread in the bunch parameters. In addition longitudinal coupled-bunch instabilities can appear, caused by the cavity impedance at the fundamental. Both issues can be mitigated by using an rf feedback around the amplifier and cavity, a technique used in many high intensity machines including the Large Hadron Collider (LHC). Compared to the LHC machine, the energy increase and the radiation loss for the Future Circular hadron-hadron Collider (FCC-hh) will be larger, resulting in a synchronous phase deviating significantly from 180 degrees. The solutions adopted for the LHC must therefore be revisited. This paper evaluates several beam loading compensation schemes for this machine.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW084
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW085	Intensity Dependent Effects in the ILC BDS	wakefield, luminosity, simulation, linear-collider	305
	P. Korysko, A. Latina CERN, Geneva, Switzerland P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	The International Linear Collider (ILC) is an electron-positron collider being considered for the post-LHC era. Its Beam Delivery System (BDS) receives the beam from the main linac. This beam is then focused to the nanometer scale after going through collimators, beam diagnostic systems, strong magnets, etc. Effects such as wakefields due to resistive-wall, BPMs and collimators make the system very sensitive to the beam intensity. Understanding these effects is crucial in order to demonstrate that the nominal beam size at the Interaction Point (IP) can be reached in realistic scenarios. In this paper, results of the intensity dependence effects in the ILC BDS, simulated with PLACET, are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW085
About •	paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW086	Intensity Dependent Effects at ATF2, KEK	simulation, linear-collider, wakefield, electron	308
	P. Korysko, A. Latina CERN, Geneva, Switzerland P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom A. Faus-Golfe LAL, Orsay, France K. Kubo, T. Okugi KEK, Ibaraki, Japan
	The Accelerator Test Facility 2 (ATF2) at KEK is a prototype for the Final Focus Systems of the future e⁺e⁻ linear colliders, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). In this paper both simulation and experimental results are presented with special emphasis on intensity-dependent effects. The importance of these effects is shown using the PLACET code and realistic ATF2 machine simulations (including beam jitter, misalignment, wakefield, Beam Based Alignment (BBA) correction, …). The latest experimental results are also presented, in particular the impact of the beam intensity on the beam size at the IP.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW086
About •	paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP003	Positron Source for FCC-ee	positron, target, linac, electron	424
	I. Chaikovska, R. Chehab, A. Faus-Golfe, Y. Han LAL, Orsay, France A. Apyan ANSL, Yerevan, Armenia Y. Enomoto, K. Furukawa, T. Kamitani, F. Miyahara, M. Satoh, Y. Seimiya, T. Suwada KEK, Ibaraki, Japan P.V. Martyshkin BINP SB RAS, Novosibirsk, Russia S. Ogur, K. Oide, Y. Papaphilippou, L. Rinolfi, P. Sievers, F. Zimmermann CERN, Geneva, Switzerland
	The FCC-ee is a high-luminosity, high-precision circular collider to be constructed in a new 100 km tunnel in the Geneva area. The physics case is well established and the FCC-ee operation is foreseen at 91 GeV (Z-pole), 160 GeV (W pair production threshold), 240 GeV (Higgs resonance) and 365 GeV (t-tbar threshold). Due to the large 6D production emittance and important thermal load in the production target, the positron injector, in particular the positron source, is one of the key elements of the FCC-ee, requiring special attention. To ensure high reliability of the positron source, conventional and hybrid targets are currently under study. The final choice of the positron target will be made based on the estimated performances. In this framework, we present a preliminary design of the FCC-ee positron source, with detailed simulation studies of positron production, capture and primary acceleration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP003
About •	paper received ※ 03 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP005	Field Quality for the Hadron Option of Future Circular Collider	injection, dipole, octupole, target	4397
	B. Dalena, D. Boutin CEA-IRFU, Gif-sur-Yvette, France A. Chancé CEA-DRF-IRFU, France E. Cruz Alaniz The University of Liverpool, Liverpool, United Kingdom D. Schulte CERN, Meyrin, Switzerland
	Funding: This Research and Innovation Action project submitted to call H₂020-INFRADEV-1-2014-1 receives funding from the European Union’s H₂020 Framework Program under grant agreement No. 654305. The updated field quality for the baseline design option of the Nb₃Sn dipoles for Future Circular Collider (FCC-hh) is discussed. The impact on the expected dynamic aperture is shown at injection and collision energy and the consequent non-linear correction schemes together with their integration in the optics are defined.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP005
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP007	Design of a Compact Power Distribution System for the ILC	cavity, cryomodule, ECR, acceleration	436
	B. Du, N. Liu Sokendai - Hayama, Hayama, Japan T. Matsumoto, S. Michizono, T. Miura, F. Qiu KEK, Ibaraki, Japan T. Matsumoto, T. Miura, F. Qiu Sokendai, Ibaraki, Japan
	The Local power distribution system (LPDS) of the In-ternational Linear Collider (ILC) is constructed to transmit RF power from the 10 MW klystron to 39 cavi-ties. Each eight or nine 9-cell cavities is assembled in one cryomodule. The variable hybrid is used to adjust the power dividing ratio due to the different required power of each cavity and the variable phase shifter is used to compensate the phase drift caused by the variable hybrid. More compact LPDS is expected to be integrated on the cryomodule decreasing financial cost. We re-design the shorter variable hybrid with a margin of power ratio of ±25% and phase shifter of total phase range being 35° for compensating hybrid and on-crest searching. Fixed phase shifters are designed to adjust the phase difference between adjacent cavities for beam acceleration. Simu-lated results of total compact LPDS can meet the re-quirements of ILC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP007
About •	paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP009	Effect of Initial Parameters on the Super Flat Beam Generation with the Phase-Space Rotation for Linear Colliders	emittance, simulation, gun, solenoid	442
	M. Kuriki, R. Tamura HU/AdSM, Higashi-Hiroshima, Japan H. Hayano, X.J. Jin, T. Konomi, Y. Seimiya, N. Yamamoto KEK, Ibaraki, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan P. Piot Northern Illinois University, DeKalb, Illinois, USA J.G. Power ANL, Argonne, Illinois, USA K. Sakaue The University of Tokyo, The School of Engineering, Tokyo, Japan M. Washio RISE, Tokyo, Japan
	Funding: This work is partly supported by Japan-US Cooperative grant for scientific studies, Grant aid for scientific study by MEXT Japan (KAKENHI) Kiban B. Linear collider is a concept to realize e⁺e⁻ collision beyond the limitation of the ring colliders by the synchrotron radiation. To obtain an enough luminosity, eg. 1.0·10⁺³⁴ cm^-2sec^-1, the beam is focused down to nano-meter size with a high aspect ratio. This super flat beam is useful to improve the luminosity and to compensate the beam-beam effect, eg. Beamstrahlung. In a conventional design, the super-flat beam is produced by radiation damping in a storage ring. We propose to produce this super-flat beam with phase-space rotation techniques. We employ both Round to Flat Beam Transformation and Transverse to Longitudinal Emittance eXchange, the super flat beam can be generated by controlling the space-charge effect which spoiled the performance. We present the RFBT performance with respect to the initial conditions, i.e. beam size, initial emittance, solenoid field (strength and profile), etc.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP009
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP014	NICA Accelerator Complex at JINR	booster, dipole, proton, injection	452
	E. Syresin, O.I. Brovko, A.V. Butenko, E.E. Donets, A.R. Galimov, E.V. Gorbachev, A. Govorov, V. Karpinsky, V. Kekelidze, H.G. Khodzhibagiyan, S.A. Kostromin, A.D. Kovalenko, O.S. Kozlov, I.N. Meshkov, A.V. Philippov, A.O. Sidorin, V. Slepnev, A.V. Smirnov, G.V. Trubnikov, A. Tuzikov, V. Volkov JINR, Dubna, Moscow Region, Russia
	Status of the project of NICA accelerator complex, which is under construction at JINR (Dubna, Russia), is presented. The main goal of the project is to provide ion beams for experimental studies of hot and dense baryon-ic matter and spin physics. The NICA collider will pro-vide heavy ion collisions in the energy range of √sNN=4/11 GeV at average luminosity of L=1.1027cm−2·s−1 for 197Au⁷⁹⁺ nuclei and polarized proton collisions in energy range of √sNN=12/27 GeV at lumi-nosity of L ≥ 1031cm−2·s⁻¹. NICA accelerator complex will consist of two injector chains, 578 MeV/u supercon-ducting (SC) booster synchrotron, the existing SC syn-chrotron (Nuclotron), and the new SC collider that has two storage rings each of 503 m circumference. Con-structing facility is based on Nuclotron-technology of SC magnets with iron yoke. Hollow SC cable cooled by two-phase He-flux used for operation with 10 kA currents and 1Hz cycling rate. Both stochastic and electron cooling methods are used for the beam accumulation and its stability maintenance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP014
About •	paper received ※ 29 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP015	Longitudinal Particle Dynamics in NICA Collider	bunching, injection, accumulation, acceleration	455
	E. Syresin, A.V. Eliseev, A.V. Smirnov JINR, Dubna, Moscow Region, Russia N.V. Mityanina, V.M. Petrov, E. Rotov, A.G. Tribendis BINP SB RAS, Novosibirsk, Russia
	A specific feature of the NICA acceleration complex is high luminosity of colliding beams. Three types of RF stations will be used in the NICA Collider to reach the necessary beam parameters. The first one is for accumulation of particles in the longitudinal phase space with the moving burrier buckets under action of stochastic and/or electron cooling systems. The second and third RF stations are for formation of the final bunch size in the colliding regime. This report presents numerical simulations of longitudinal beam dynamics which taken into account the longitudinal space charge effect during the accumulation and bunching procedures. Influence of space effects leads to some decrease in the accumulation efficiency and requires special manipulation with the 2nd and 3rd RF stations during the adiabatic capture and bunching procedures.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP015
About •	paper received ※ 29 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP016	Intra-Bunch Energy Spread Minimisation for CLIC Operation at a Centre-of-Mass Energy of 350 GeV	linac, luminosity, emittance, linear-collider	458
	N. Blaskovic Kraljevic, D. Arominski, D. Schulte CERN, Meyrin, Switzerland
	The first stage of the electron-positron Compact Linear Collider (CLIC) is designed with a centre-of-mass energy of 380 GeV. A dedicated threshold scan in the vicinity of 350 GeV is envisioned with a total integrated luminosity of 100 fb^-1. This scan calls for a very small intra-bunch energy spread in order to achieve an excellent collision energy resolution. This paper presents an optimised assignment of RF accelerating gradients and phases in the CLIC main linac for operation at 350 GeV, which minimises the energy spread at the end of the main linac whilst preserving a small emittance growth. Variation of the bunch length and charge is studied in order to further reduce the energy spread; the effect on both the peak and total luminosity is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP016
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP017	Beam Orbit Correction in the CLIC Main Linac Using a Small Subset of Correctors	linac, emittance, quadrupole, ground-motion	461
	N. Blaskovic Kraljevic, D. Schulte CERN, Meyrin, Switzerland
	Beam orbit correction in future linear colliders, such as the Compact Linear Collider (CLIC), is essential to mitigate the effect of accelerator element misalignment due to ground motion. The correction is performed using correctors distributed along the accelerator, based on the beam position monitor (BPM) readout from the preceding bunch train, with a train repetition frequency of 50 Hz. This paper presents the use of the MICADO algorithm* to select a subset of N ~ 10 correctors (from a total of 576) to be used for orbit correction in the designed 380 GeV centre-of-mass energy first-stage of CLIC. The optimisation of the number N of correctors, the algorithm’s gain and the corrector step size is described, and the impact of a number of BPMs and correctors becoming unavailable is addressed. The application of a MICADO algorithm to perform dispersion free steering, by reducing the beam orbit difference between two beams with different energies, is discussed. * B. Autin & Y. Marti, "Closed orbit correction of A.G. machines using a small number of magnets", CERN-ISR-MA/73-17, 1973.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP017
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP018	Beam-Based Beamline Element Alignment for the Main Linac of the 380 GeV Stage of CLIC	emittance, linac, alignment, wakefield	465
	N. Blaskovic Kraljevic, D. Schulte CERN, Meyrin, Switzerland
	The extremely small vertical beam size required at the interaction point of future linear colliders, such as the Compact Linear Collider (CLIC), calls for a very small vertical emittance. The strong wakefields in the high frequency 12 GHz CLIC accelerating structures set tight tolerances on the alignment of the main linac’s beamline elements and on the correction of the beam orbit through them in order to mantain a small emittance growth. This paper presents the emittance growth due to each type of beamline element misalignment in the designed 380 GeV centre-of-mass energy first-stage of CLIC, and the emittance growth following a series of beam-based alignment (BBA) procedures. The BBA techniques used are one-to-one steering, followed by dispersion free steering and finally accelerating structure alignment using wakefield monitors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP018
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP022	K-Modulation in Future High Energy Colliders	quadrupole, luminosity, optics, power-supply	476
	M. Hofer, F.S. Carlier, R. Tomás CERN, Geneva, Switzerland
	K-Modulation of the quadrupoles closest to the interaction point (IP) has been an indispensable tool to accurately measure the beta-function in the interaction point (β^) in the Large Hadron Collider (LHC) at CERN. K-Modulation may become even more important to control the lower β^ and reach the design luminosities in the High-Luminosity LHC (HL-LHC) and the Future Circular Collider (FCC). K-Modulation results also provide important input for the luminosity calibration and help in the identification and correction of errors in the machines. This paper presents a method for determining β^* using K-Modulation adapted to the characteristic layout of both colliders. Using the latest models for the HL-LHC and the FCC-hh, estimated uncertainties on the measurements are presented. The results are compared to the accuracy of an alternative modulation scheme using a different powering scheme.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP022
About •	paper received ※ 06 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPMP023	Dynamic Aperture at Injection Energy for the HE-LHC	dipole, injection, lattice, dynamic-aperture	480
	M. Hofer, M. Giovannozzi, J. Keintzel, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland L. van Riesen-Haupt JAI, Oxford, United Kingdom
	As part of the Future Circular Collider study, the High Energy LHC (HE-LHC) is a proposed hadron collider situated in the already existing LHC tunnel. It aims at achieving a center of mass energy of 27 TeV, almost doubling the design c.o.m. energy of the LHC. This increase in energy relies on the use of 16 T Nb₃Sn dipoles to be developed for the FCC-hh. The field quality of these dipoles is expected to have a big impact on the Dynamic Aperture (DA) at injection energy and subsequently tracking studies are conducted to evaluate the impact of magnetic field errors on the beam dynamics. In the following the results of these studies for the different injection energies considered for the HE-LHC are presented and a possible strategy for increasing the DA are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP023
About •	paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP025	Moving Long-range Beam-beam Encounters in Heavy-ion Colliders	proton, emittance, injection, acceleration	488
	M.A. Jebramcik, J.M. Jowett CERN, Geneva, Switzerland
	Asymmetric ion beam collisions like proton-lead in the LHC or gold-deuteron in RHIC have become major components of heavy-ion physics programmes. The injection and ramp of two different ion species with the same magnetic rigidity and consequently unequal revolution frequencies generate moving long-range beam-beam encounters in the interactions regions of the collider. These encounters led to fast beam losses and can cause emittance blow-up as observed in RHIC in the early 2000s and, more recently, in 2015. Yet such effects are absent at the LHC so the difference between the two colliders requires explanation. Tools and models have been developed to describe the beam dynamics of moving long-range beam-beam encounters and to predict the evolution of emittance and other beam parameters. Besides presenting results for RHIC and the LHC we give an outlook for the HL-LHC and potential operational restrictions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP025
About •	paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPMP029	Analysis on Bunch-by-Bunch Beam Losses at 6.5 TeV in the Large Hadron Collider	luminosity, betatron, beam-losses, operation	500
	K. Paraschou, G. Iadarola, N. Karastathis, S. Kostoglou, Y. Papaphilippou, L. Sabato CERN, Geneva, Switzerland S. Kostoglou National Technical University of Athens, Zografou, Greece K. Paraschou AUTH, Thessaloniki, Greece
	In 2018, a large fraction of the physics data taking at the Large Hadron Collider has been performed with a beam energy of 6.5 TeV, the nominal bunch spacing of 25 ns and beta functions at the high luminosity interaction points of 30 cm. In order to maximize the integrated luminosity, the crossing angles are gradually reduced as the beam intensity reduces due to luminosity burn-off. In these conditions the beam lifetime is visibly affected by collective effects and in particular by beam-beam interaction and electron cloud effects. By analyzing the beam losses at a bunch-by-bunch level, it is possible to disentangle the contributions from different effects and to assess the impact on the losses of changes applied to the machine configuration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP029
About •	paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP034	Tuning Studies of the CLIC 380 Gev Final Focus System	sextupole, luminosity, alignment, linear-collider	512
	J. Ögren, A. Latina, D. Schulte, R. Tomás CERN, Meyrin, Switzerland
	We present tuning studies of the Compact Linear Collider final-focus system under static imperfections including transverse misalignments, roll errors and magnetic strength errors. The tuning procedure consists of beam-based alignment for correcting the linear part of the system followed by sextupole pre-alignment and use of multipole tuning knobs. The sextupole pre-alignment is very robust and allows the tuning time to be greatly reduced.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP034
About •	paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP035	Effect of Emittance Constraints on Monochromatization at the Future Circular e⁺e⁻ Collider	emittance, luminosity, radiation, photon	516
	M.A. Valdivia García, F. Zimmermann CERN, Meyrin, Switzerland
	Direct s-channel Higgs production in e+e− collisions is of interest if the collision energy spread can be comparable to the natural width of the standard model Higgs boson. At the Future Circular e⁺e⁻ Collider (FCC-ee), a monochromatization scheme could be employed in order to reduce the collision energy spread to the target value. This may be achieved by introducing a non-zero horizontal dispersion of opposite sign for the two colliding beams at the interaction point. In this case, the beamstrahlung increases the horizontal emittance in addition to energy spread and bunch length. The vertical emittance could either be tuned to a certain minimum value, possibly limited by the diagnostics resolution, or it could scale linearly with the horizontal emittance. For the FCC-ee at 62.5 GeV beam energy, we optimize the IP optics and beam parameters, considering these two different assumptions for the vertical emittance. We derive the maximum achievable luminosity as a function of collision energy spread for either case.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP035
About •	paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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MOPMP038	Investigation of CLIC 380 GeV Post-Collision Line	simulation, site, dipole, linear-collider	528
	R.M. Bodenstein, A. Abramov, S.T. Boogert, P. Burrows, L.J. Nevay JAI, Oxford, United Kingdom D. Schulte, R. Tomás CERN, Meyrin, Switzerland
	It has been proposed that the Compact Linear Collider (CLIC) be commissioned in stages, starting with a lower-energy, 380 GeV version for the first stage, and concluding with a 3 TeV version for the final stage. In the Conceptual Design Report (CDR) published in 2012, the post-collision line is described for the 3 TeV and 500 GeV stages. However, the post-collision line for the 380 GeV design was not investigated. This work will describe the simulation studies performed in BDSIM for the 380 GeV post-collision line.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP038
About •	paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPMP048	LHC Doubler: CIC Dipole Technology May Make It Feasible and Affordable	dipole, multipole, injection, hadron	552
	P.M. McIntyre Texas A&M University, College Station, USA J. Breitschopf, J.N. Kellams, A. Sattarov ATC, College Station, Texas, USA D.C.V. Chavez Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
	There is new physics-driven interest in the concept of an LHC doubler with collision energy of 30 TeV and high luminosity. The cost-driver challenge for its feasibility is the ring of 16 T dual dipoles. Recent developments in cable-in-conduit (CIC) technology offer significant benefit for this purpose. The CIC windings provide robust stress management at the cable level and facilitate forming of the flared ends without degradation. The CIC windings provide a basis for hybrid windings, in which the innermost layers that operate in high field utilize Bi-2212, the center layers utilize Nb₃Sn, and the outer layers utilize NbTi. Cryogen flows through the interior of all cables, so that heat transfer can be optimized throughout the windings. The design of the 18 T dipole and the 23 kA CIC conductor will be presented. Particular challenges for integration in an LHC doubler will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP048
About •	paper received ※ 18 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPMP049	6 T Cable-in-conduit Dipole to Double the Ion Energy for JLEIC	dipole, electron, injection, luminosity	556
	P.M. McIntyre, J. Breitschopf, J. Gerity Texas A&M University, College Station, USA J. Breitschopf, D.C.V. Chavez, J.N. Kellams, A. Sattarov ATC, College Station, Texas, USA
	The proposed electron-ion collider JLEIC would make high-luminosity collisions of polarized ions and polarized electrons with electron energy up to 12 GeV and ion energy up to 40 GeV/u. Both the luminosity and the collision energy could be increased by doubling the dipole field in the ion ring from 3 T to 6 T, and the enhanced performance would access the full range of parameters for the physics objectives of the project. The Texas A&M group has developed the large-aperture 3 T dipoles for the baseline project, based upon a novel superconducting cable-in-conduit. (CIC). A closely similar 6 T design is being developed, utilizing a 2-layer CIC. Details of the magnet design and development of the 2-layer CIC will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP049
About •	paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPMP053	Numerical Optimization of DC Wire Compensation in HL-LHC	operation, luminosity, hadron, simulation	570
	K. Skoufaris, S.D. Fartoukh, N. Karastathis, Y. Papaphilippou, D. Pellegrini, A. Poyet, A. Rossi, G. Sterbini CERN, Meyrin, Switzerland
	The electromagnetic field generated from a set of DC wires parallel to the beam opens the path to the compensation of the beam-beam long-range (BBLR) interactions for the future operation of large hadron colliders, in particular for the upcoming High Luminosity upgrade of the Large Hadron Collider (HL-LHC). The effectiveness and simplicity of a current carrying wire are critical for overcoming some technical constraints of the machine. In order to better understand the potential of this device for the HL-LHC, various simulation studies are presented. The different observables are the dynamic aperture and the frequency analysis.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP053
About •	paper received ※ 03 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB031	Progress of Conceptual Study for the Accelerators of a 2-7GeV Super Tau Charm Facility at China	luminosity, factory, electron, operation	643
	Q. Luo, W. Li, D.R. Xu USTC/NSRL, Hefei, Anhui, People’s Republic of China W.W. Gao, J.Q. Lan Fujian University of Technology, Fuzhou, People’s Republic of China
	Funding: Supported by National Natural Science Foundation of China U1832169 and the Double Fist-Class University Project Foundation of USTC. This paper shows the progress of the conceptual study for the accelerators of a super tau charm facility in China. Since the BEPCII will finish its historical mission in 5~10 years and its upgrade plan will only achieve a small luminosity enhancement of 3~5 times, a new next generation tau-charm collider will play an irreplaceable role in future high energy physics study. The luminosity of this successor is about 5×10³⁴cm⁻²s⁻¹ pilot and 1×10³⁵cm⁻²s⁻¹ nominal, with the electron beam longitudinally polarized at the IP. The general scheme of the accelerators and the beam pa-rameters are shown. Several key technologies such as beam polarization and beam emittance diagnostics are also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB031
About •	paper received ※ 14 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
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MOPRB041	Spin Resonance Strength in the Transparent Spin Mode of the NICA Collider	polarization, solenoid, resonance, proton	656
	Y. Filatov, S.V. Vinogradov MIPT, Dolgoprudniy, Moscow Region, Russia A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia A.D. Kovalenko JINR, Dubna, Moscow Region, Russia
	To implement the polarization program at the NICA complex (Dubna, Russia) the novel mode of ion polarization control - the transparent spin mode - is planned to use. To set up the transparent spin mode in the NICA collider two solenoidal snakes will be placed in straights of the Multi Purpose Detector (MPD) and the Spin Physics Detector (SPD). The beam polarization at SPD will be controlled by means of ‘‘weak’’ solenoids. The main characteristic of the transparent spin mode is the spin resonance strength, which consists of two parts: a coherent part arising due to additional transverse and longitudinal fields on the beam trajectory deviating from the design orbit and an incoherent part associated with the particles’ betatron and synchrotron oscillations (beam emittances). The resonance strength allows one to formulate requirements on the magnitudes of the control solenoids’ fields. The theoretical analysis, calculation and spin tracking simulation of the spin resonance strength in the whole momentum range of the NICA collider are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB041
About •	paper received ※ 01 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
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MOPRB048	Collimation System Studies for the FCC-hh	collimation, proton, simulation, hadron	669
	R. Bruce, A. Abramov, A. Bertarelli, M.I. Besana, F. Carra, F. Cerutti, M. Fiascaris, G. Gobbi, A.M. Krainer, A. Lechner, A. Mereghetti, D. Mirarchi, J. Molson, M. Pasquali, S. Redaelli, D. Schulte, E. Skordis, M. Varasteh Anvar CERN, Geneva, Switzerland A. Abramov JAI, Egham, Surrey, United Kingdom A. Faus-Golfe LAL, Orsay, France M. Serluca IN2P3-LAPP, Annecy-le-Vieux, France
	The Future Circular Collider (FCC-hh) is being designed as a 100 km ring that should collide 50 TeV proton beams. At 8.3 GJ, its stored beam energy will be a factor 28 higher than what has been achieved in the Large Hadron Collider, which has the highest stored beam energy among the colliders built so far. This puts unprecedented demands on the control of beam losses and collimation, since even a tiny beam loss risks quenching superconducting magnets. We present in this article the design of the FCC-hh collimation system and study the beam cleaning through simulations of tracking, energy deposition, and thermo-mechanical response. We investigate the collimation performance for design beam loss scenarios and potential bottlenecks are highlighted.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB048
About •	paper received ※ 18 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB049	Study of Beam-Gas Interactions at the LHC for the Physics Beyond Colliders Fixed-Target Study	target, proton, experiment, simulation	673
	C. Boscolo Meneguolo, R. Bruce, F. Cerutti, M. Ferro-Luzzi, M. Giovannozzi, A. Mereghetti, J. Molson, S. Redaelli CERN, Geneva, Switzerland A. Abramov JAI, Egham, Surrey, United Kingdom
	Among several working groups formed in the framework of Physics Beyond Colliders study, launched at CERN in September 2016, there is one investigating specific fixed-target experiment proposals. Of particular interest is the study of high-density unpolarized or polarized gas target to be installed in the LHCb detector, using storage cells to enhance the target density. This work studies the impact of the interactions of 7 TeV proton beams with such gas targets on the LHC machine in terms of particle losses.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB049
About •	paper received ※ 17 April 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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MOPRB051	Collimation System Upgrades for the High Luminosity Large Hadron Collider and Expected Cleaning Performance in Run 3	collimation, proton, hadron, dipole	681
	A. Mereghetti, R. Bruce, N. Fuster-Martínez, D. Mirarchi, S. Redaelli CERN, Geneva, Switzerland
	In the framework of the High-Luminosity Large Hadron Collider project (HL-LHC), the LHC collimation system needs important upgrades to cope with the foreseen brighter beams. New collimation hardware will be installed in two phases, the first one during the LHC second Long Shutdown (LS2), in 2019-20, followed by a second phase starting in 2024 (LS3). This paper reviews the collimation upgrade plans for LS2, focused on a first impedance reduction of the system, through the installation of collimators based on new materials, and the improvement of collimation cleaning, achieved by adding new collimators in the cold dispersion suppressor regions. The performance of the new system in terms of cleaning inefficiency for proton and lead ion beams is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB051
About •	paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB058	Collimation of Partially Stripped Ion Beams in the LHC	collimation, simulation, operation, hadron	700
	A. Abramov, L.J. Nevay JAI, Egham, Surrey, United Kingdom R. Bruce, N. Fuster-Martínez, A.A. Gorzawski, M.W. Krasny, J. Molson, S. Redaelli, M. Schaumann CERN, Meyrin, Switzerland
	In the scope of the Physics Beyond Colliders studies, the Gamma Factory initiative proposes the use of partially stripped ions as a driver of a new type, high intensity photon source in CERN’s Large Hadron Collider (LHC). In 2018, the LHC accelerated and stored partially stripped 208-Pb-81+ ions for the first time. The collimation system efficiency recorded during this test was found to be prohibitively low. The worst losses were localised in the dispersion suppressor (DS) of the betatron-cleaning insertion. Analytic arguments and simulations show that the large losses are driven by the stripping of the remaining electron from the Pb nucleus by the primary collimators. The rising dispersion in the DS pushes the resulting off-rigidity, fully-stripped ions into the aperture of the superconducting magnets. In this study the measured loss maps are compared against results from simulations. Different mitigation strategies are outlined, including a dispersion suppressor (DS) collimator, crystal collimation or an orbit bump.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB058
About •	paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB059	Collimation of Heavy-Ion Beams in the HE-LHC	collimation, proton, hadron, simulation	704
	A. Abramov, L.J. Nevay JAI, Egham, Surrey, United Kingdom R. Bruce, M.P. Crouch, N. Fuster-Martínez, A. Mereghetti, J. Molson, S. Redaelli CERN, Meyrin, Switzerland
	A design study for a future collider to be built in the LHC tunnel, the High-Energy Large Hadron Collider (HE-LHC), has been launched as part of the Future Circular Collider (FCC) study at CERN. It would provide proton collisions at a centre-of-mass energy of 27 TeV as well as collisions of heavy ions at the equivalent magnetic rigidity. HE-LHC is being designed under the stringent constraint of using the existing tunnel and therefore the resulting lattice and optics differ in layout and phase advance from the LHC. It is necessary to evaluate the performance of the collimation system for ion beams in HE-LHC in addition to proton beams. In the case of ion beams, the fragmentation and electromagnetic dissociation that relativistic heavy ions can undergo in collimators, as well as the unprecedented energy per nucleon of the HE-LHC, requires dedicated simulations. Results from a study of collimation efficiency for the nominal lead ion (Pb-82-208) beams performed with the SixTrack-FLUKA coupling framework are presented. These include loss maps with comparison against an estimated quench limit as well as detailed considerations of loss spikes in the superconducting aperture for critical sections of the machine such as the dispersion suppressors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB059
About •	paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPRB072	eRHIC in Electron-Ion Operation	operation, electron, heavy-ion, hadron	738
	W. Fischer, E.C. Aschenauer, E.N. Beebe, M. Blaskiewicz, K.A. Brown, D. Bruno, K.A. Drees, C.J. Gardner, H. Huang, T. Kanesue, C. Liu, M. Mapes, G.T. McIntyre, M.G. Minty, C. Montag, S.K. Nayak, M. Okamura, V. Ptitsyn, D. Raparia, J. Sandberg, K.S. Smith, P. Thieberger, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, A. Zaltsman, A. Zelenski BNL, Upton, Long Island, New York, USA
	Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy. The design effort for the electron-ion collider eRHIC has concentrated on electron-proton collisions at the highest luminosities over the widest possible energy range. The present design also provides for electron-nucleon peak luminosities of up to 4.7·10³³ cm^-2s⁻¹ with strong hadron cooling, and up to 1.7·10³³ cm^-2s⁻¹ with stochastic cooling. Here we discuss the performance limitations and design choices for electron-ion collisions that are different from the electron-proton collisions. These include the ion bunch preparation in the injector chain, acceleration and intrabeam scattering in the hadron ring, path length adjustment and synchronization with the electron ring, stochastic cooling upgrades, machine protection upgrades, and operation with polarized electron beams colliding with either unpolarized ion beams or polarized He-3.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB072
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB098	An Increased Extraction Energy Booster Complex for the Jefferson Lab Electron Ion Collider	booster, electron, extraction, proton	797
	E.A. Nissen JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript. The proposed Jefferson Lab Electron Ion Collider (JLE-IC) envisions an ion complex composed of an ion linac, two booster synchrotrons and a collider ring. The evolving design of the JLEIC booster required an increase in the extraction energy of the booster from 8 to 12.1 GeV kinetic energy, necessitating two machines instead of one. The decision was also made to switch to warm magnets, thus increasing the total radius of the 8 GeV booster. The second booster is now the same size as the collider rings. In this work we present the new designs for JLEIC’s Low Energy Booster (LEB) and High Energy Booster (HEB).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB098
About •	paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPTS065	Alternative Design of CEPC LINAC	linac, positron, electron, booster	1005
	C. Meng, J. Gao, X.P. Li, G. Pei, J.R. Zhang IHEP, Beijing, People’s Republic of China
	Circular Electron-Positron Collider (CEPC) is a 100 km ring e⁺ e⁻ collider for a Higgs factory. The injector is composed of a Linac and a Booster. The baseline design of CEPC Linac is a normal conducting S-band linear accelerator with frequency in 2860 MHz, which can provide electron and positron beam at an energy up to 10 GeV and bunch charge up to 3 nC. To reduce the design difficulty of booster and booster magnet at low energy part, an alternative design of the Linac with C-band accelerating structure at high energy part is proposed and the energy is up to 20 GeV. The compre-hensive consideration of Linac design and damping ring design will be discussed. In this paper, the physics design of this scheme is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS065
About •	paper received ※ 16 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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MOPTS093	Ultra-High Vacuum Characterization of Molybdenum-Carbide Graphite for HL-LHC Collimators	vacuum, collimation, site, proton	1078
	F. Carra, C. Accettura, A. Bertarelli, G. Bregliozzi, G. Cattenoz, S. Redaelli, M. Taborelli CERN, Meyrin, Switzerland M. Beghi POLIMI, Milano, Italy J. Guardia Valenzuela Universidad de Zaragoza, Zaragoza, Spain
	Funding: This work has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No. 730871. Research supported by the HL-LHC project In view of the High-Luminosity upgrade of the Large Hadron Collider (LHC) collimation system, a family of novel molybdenum-carbide graphite (MoGr) composites was developed to meet the challenging requirements of HL-LHC beam-halo collimation, in particular the electrical conductivity and thermo-mechanical performances. The Ultra-High Vacuum (UHV) behaviour of this material was extensively characterized to assess its compatibility with the accelerator’s specifications. The results presented in this paper correlate the outgassing behaviour with the microscopic features of MoGr compared to other graphite-based materials. Residual gas analysis (RGA) was exploited to optimize post-production treatments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS093
About •	paper received ※ 12 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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TUPMP020	The Research on the Calibration of Direct-Current Current Transformers	power-supply, experiment, factory, data-acquisition	1280
	C. Han, Y. Gao, X.L. Guo, P. Liu IHEP, Beijing, People’s Republic of China
	The measurement accuracy of direct current-current transformer (DCCT) is one of the key factors influencing the output of high-precision direct current power supply. In this paper, a calibration system designed by measuring resistance principle with a high accuracy direct current comparator (DCC) was presented for DCCT whose measurement accuracy is better than 10^-5. The system can achieve high-precision calibration of DCCT within the measurement range of 0-400 A, and the uncertainty of the system calibration is better than 1.1×10-6 in the whole range. The accuracy and linearity of DCCT are tested to verify the accuracy of the whole calibration system, thereby the current accuracy of the magnet power supply can be further improved.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP020
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPMP035	Design of the Vacuum System of the FCC-ee Electron-Positron Collider	vacuum, photon, dipole, quadrupole	1319
	R. Kersevan, C. Garion CERN, Geneva, Switzerland
	The Future Circular Collider (FCC) Design Study includes the twin storage ring (FCC-ee) where electrons and positrons are stored and made to collide inside two detectors. The vacuum system of FCC-ee must be designed in order to deal with a lower-energy (45.6 GeV), high-current (1390 mA) Z-pole machine and at a later stage with a higher-energy (182.5 GeV) low-current (5.4 mA). The former machine is the most challenging one from the point of view of vacuum, since the photon-stimulated desorption (PSD) generated by the copious synchrotron radiation (SR) fans is quite large. While several concepts have been considered at the beginning, the design retained for the Conceptual Design Report (CDR) is one where the cross-section of the vacuum chamber (VC) in the arcs is a scaled-down version of the one implemented in the SUPERKEKB collider. Contrary to SUPERKEKB tough, the SR fans are absorbed by many short absorbers, with average spacing of 5.8 m. This allow a localization of the PSD gas load and to place lumped pumps in front of the SR absorbers, to maximize the pumping efficiency. The VC design is compatible with the design of the common-yoke dipoles and quadrupoles. The VC material is copper alloy. Optimization of the pressure profiles has been carried out by means of extensive coupled montecarlo simulations, for SR and molecular flow. For the higher energy versions of the machine, for which the SR spectra are characterized by critical energies well above the Compton edge, the localized absorbers facilitate also shielding the tunnel and any radiation-sensitive machine components from X-ray photon damage, by installing short high-Z material around the absorbers. The major features of the CDR relevant for vacuum will be highlighted in the paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP035
About •	paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPMP038	Summary of Modelling Studies on the Beam Induced Vacuum Effects in the FCC-hh	vacuum, electron, photon, synchrotron	1331
	I. Bellafont, R. Kersevan, L. Mether CERN, Geneva, Switzerland
	Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305. EuroCirCol is a conceptual design study of a Future Circular Collider (FCC-hh) which aims to expand the current energy and luminosity frontiers that the LHC has established. The vacuum chamber of this 50 TeV, 100 km collider, will have to cope with unprecedented levels of synchrotron radiation power for proton colliders, dealing simultaneously with a tighter magnet aperture. Since the high radiation power and photon flux will release large amounts of gas into the system, the difficulty to keep a low level of residual gas density increases considerably compared with the LHC. This article presents a study of the beam induced vacuum effects for the FCC-hh novel conditions, the different phenomena which, owing to the presence of the beam, have an impact on the vacuum level of the accelerator. To achieve this, a novel beam screen has been proposed, featuring specific mitigating measures aimed at dealing with the beam induced effects. It is concluded that thanks to the new beam screen design, the vacuum level in the FCC-hh shall be adequate, allowing to reach the molecular density requirement of better than 10¹⁵ H₂/m3 with baseline beam parameters within the first months of conditioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP038
About •	paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPRB112	JLEIC: A High Luminosity Polarized Electron-Ion Collider at Jefferson Lab	electron, luminosity, proton, emittance	1916
	Y. Zhang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. The recent National Academies of Science Review concluded the science questions that could be answered by an electron-ion collider are significant to advancing our understanding of the atomic nuclei that make up all visible matter in the universe. To meet this science need, a high luminosity polarized electron-ion collider (JLEIC) was envisioned at Jefferson Lab, based on the existing CEBAF recirculated SRF electron linac. Over the past 16 years, Jefferson Lab has been actively engaged in the design study and accelerator R&D for JLEIC, a comprehensive Pre-Conceptual Design Report has been completed recently. The JLEIC baseline design has also been continuously optimized including extending the CM energy to 100 GeV. In this paper, we present a summary of the JLEIC baseline design and also briefly discuss the accelerator R&D.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB112
About •	paper received ※ 07 June 2019 paper accepted ※ 07 June 2019 issue date ※ 21 June 2019
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TUPTS099	Predicting the Performances of Coherent Electron Cooling with Plasma Cascade Amplifier	electron, plasma, kicker, space-charge	2150
	G. Wang, V. Litvinenko, J. Ma BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Recently, we proposed a new type of instability, Plasma Cascade Instability (PCI), to be used as the amplification mechanism of a Coherent Electron Cooling (CeC) system, which we call Plasma Cascade Amplifier (PCA). In this work, we present our analytical estimate of the cooling force as expected from a PCA- based CeC system and compare it with the simulation results. As examples, we apply our analysis to a few possible CeC systems and investigate the evolution of the circulating ion beams in the presence of cooling.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS099
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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WEYPLM1	Status of Circular Electron-Positron Collider and Super Proton-Proton Collider	injection, luminosity, booster, cavity	2244
	C.H. Yu, S. Bai, X. Cui, J. Gao, H. Geng, D.J. Gong, D. Ji, Y.D. Liu, C. Meng, Q. Qin, J.Y. Tang, D. Wang, N. Wang, Y. Wang, Y. Wei, J.Y. Zhai, Y. Zhang, H.J. Zheng, Y.S. Zhu IHEP, Beijing, People’s Republic of China
	Circular electron-positron collider (CEPC) is a dedi-cated project proposed by China to research the Higgs boson. The collider ring provides e⁺ e⁻ collision at two interaction points (IP). The luminosity for the Higgs mode at the beam energy of 120GeV is 310³⁴ cm^-2s^-1 at each IP while the synchrotron radiation (SR) power per beam is 30MW. Furthermore, CEPC is compatible with W and Z experiments, for which the beam energies are 80 GeV and 45.5 GeV respectively. The luminosity at the Z mode is higher than 1.710³⁵ cm^-2s^-1 per IP. Top-up operation is available during the data taking of high energy physics. Super Proton-Proton Collider (SPPC) is envisioned to be an extremely powerful machine, with centre mass energy of 75 TeV, a nominal luminosity of 1.0*10³⁵ cm^-2s^-1 per IP, and an integrated luminosity of 30 ab^-1 assuming 2 interaction points and ten years of running. The status of CEPC and SPPC will be introduced in detail in this paper.
	Slides WEYPLM1 [11.814 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYPLM1
About •	paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEYYPLM3	First Results of the Compensation of the Beam-Beam Effect with DC Wires in the LHC	experiment, beam-beam-effects, operation, simulation	2262
	G. Sterbini, D. Amorim, H. Bartosik, A. Bertarelli, R. Bruce, X. Buffat, F. Carra, L.R. Carver, G. Cattenoz, E. Effinger, S.D. Fartoukh, N. Fuster-Martínez, M. Gąsior, M. Gonzalez-Berges, A.A. Gorzawski, G.H. Hemelsoet, M. Hostettler, G. Iadarola, O.R. Jones, N. Karastathis, S. Kostoglou, I. Lamas Garcia, T.E. Levens, L.E. Medina Medrano, D. Mirarchi, J. Olexa, S. Papadopoulou, Y. Papaphilippou, D. Pellegrini, M. Pojer, L. Ponce, A. Poyet, S. Redaelli, A. Rossi, B. Salvachua, H. Schmickler, F. Schmidt, K. Skoufaris, M. Solfaroli, R. Tomás, G. Trad, D. Valuch, C. Xu, C. Zamantzas, P. Zisopoulos CERN, Geneva, Switzerland D. Amorim Grenoble-INP Phelma, Grenoble, France M. Fitterer, A. Valishev Fermilab, Batavia, Illinois, USA D. Kaltchev TRIUMF, Vancouver, Canada S. Kostoglou National Technical University of Athens, Zografou, Greece A.E. Levichev BINP SB RAS, Novosibirsk, Russia A. Poyet Université Grenoble Alpes, Grenoble, France
	The compensation of the long-range beam-beam interactions using DC wires is presently under study as an option for enhancing the machine performance in the frame of the High-Luminosity LHC project (HL-LHC). The original idea dates back more than 15 years. After the installation of four wire prototypes in the LHC in 2018, a successful experimental campaign was performed during the last months. The experimental setup and the main results are reported in this paper.
	Slides WEYYPLM3 [6.371 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM3
About •	paper received ※ 06 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPGW121	Update on the JLEIC Electron Collider Ring Design	electron, optics, quadrupole, solenoid	2780
	F. Lin, V.S. Morozov, Y. Zhang JLab, Newport News, Virginia, USA Y. Cai, Y.M. Nosochkov SLAC, Menlo Park, California, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515. The design concept of electron collider ring in the Jefferson Lab Electron-Ion Collider (JLEIC) is based on a small beam size at the interaction point (IP) to boost the luminosity. With a chosen beta-star at the IP, electron beam size is determined by the equilibrium emittance obtained from the linear optics design. In this paper, we present an update on the lattice design of the electron ring considering not only preservation of low beam emittance, but also optimization of geometric arrangement. In particular, recent development of the lattice design has been focused on incorporating the vertical dogleg, which brings the electron beam to the ion beam plane for collisions, in the spin rotator design. The vertical dogleg is designed with no horizontal emittance growth, controlled vertical emittance and no first-order effect on the electron polarization.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW121
About •	paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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WEPGW122	EXPERIMENTAL VERIFICATION OF TRANSPARENT SPIN MODE IN RHIC	polarization, controls, experiment, resonance	2783
	V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang JLab, Newport News, Virginia, USA P. Adams, H. Huang, F. Méot, V. Ptitsyn, W.B. Schmidke BNL, Upton, Long Island, New York, USA Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia H. Huang ODU, Norfolk, Virginia, USA A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	Funding: Supported in part by the U.S. DoE under Contract No. DE-AC05-06OR23177 and by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DoE. High electron and ion polarizations are some of the key design requirements of a future Electron Ion Collider (EIC). The transparent spin mode, a concept inspired by the figure 8 ring design of JLEIC, is a novel technique for preservation and control of electron and ion spin polarizations in a collider or storage ring. It makes the ring lattice "invisible" to the spin and allows for polarization control by small quasi-static magnetic fields with practically no effect on the beam’s orbital characteristics. It offers unique opportunities for polarization maintenance and control in Jefferson Lab’s JLEIC and in BNL’s eRHIC. The transparent spin mode has been demonstrated in simulations and we now plan to test it experimentally. We present a design of an experiment using a polarized proton beam stored in one of the RHIC rings. In the experiment, one of the RHIC rings is configured in the transparent spin mode by aligning the axes of its two Siberian snakes. The experiment goals, procedures, hardware requirements and expected results are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW122
About •	paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPGW124	Spin Response Function for Spin Transparency Mode of RHIC	resonance, polarization, controls, lattice	2791
	V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang JLab, Newport News, Virginia, USA P. Adams, H. Huang, F. Méot, V. Ptitsyn, W.B. Schmidke BNL, Upton, Long Island, New York, USA Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia H. Huang ODU, Norfolk, Virginia, USA A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	Funding: Supported by the U.S. DoE under Contracts No. DE-AC05-06OR23177 and DE-AC02-98CH10886. In the Spin Transparency (ST) mode of RHIC, the axes of its Siberian snakes are parallel. The spin tune in the ST mode is zero and the spin motion becomes degenerate: any spin direction repeats every particle turn. In contrast, the lattice of a conventional collider determines a unique stable periodic spin direction, so that the collider operates in the Preferred Spin (PS) mode. Contributions of perturbing magnetic fields to the spin resonance strengths in the PS mode are usually calculated using the spin response function. However, in that form, it is not applicable in the ST mode. This paper presents a response function formalism expanded for the ST mode of operation of conventional colliders with two identical Siberian snakes in the highly-relativistic limit. We present calculations of the spin response function for RHIC in the ST mode.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW124
About •	paper received ※ 01 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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WEPRB031	SRF Trip Caused by the Tuner in BEPCII	SRF, cavity, electron, operation	2880
	J.P. Dai, Z.H. Mi, P. Sha, Y. Sun, Q.Y. Wang, L.G. Xiao IHEP, Beijing, People’s Republic of China
	Funding: Work support by Natural Science Foundation of China (11575216) The stability and reliability of the Superconducting RF system (SRF) is generally a key issue in a large scale accelerator such as Beijing Electron Positron Collider II (BEPCII). In the past several years, SRF is one of the main factors limiting the availability of BEPCII, and many efforts have been made to fix the SCRF troubles. This paper focuses on the details of the SCRF trip caused by the tuner, which is one of the most persistent troubles and figured out till the summer of 2018.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB031
About •	paper received ※ 08 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPRB062	Spatially Resolved Dark Current in High Gradient Traveling Wave Structures	electron, linac, diagnostics, site	2956
	J. Paszkiewicz, W. Wuensch CERN, Meyrin, Switzerland P. Burrows JAI, Oxford, United Kingdom P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	High-gradient accelerating structures are known to produce field-emitted current from regions of high surface field, which are captured and accelerated by the fields within the structure. This current is routinely measured in structures under test in the CLIC high-gradient test stands using Faraday cups. This paper presents a novel technique to spatially resolve the longitudinal distribution of field emitted current by analysing downstream Faraday cup signals when the structure is fed with RF pulses much shorter than its filling time. Results from this method applied to X-band cavities operating at 100 MV/m are presented, and are compared to breakdown position distributions. A decay in emitted current as conditioning progressed in regions with a low breakdown rate and large jumps in regions with a large breakdown rate are observed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB062
About •	paper received ※ 29 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPRB069	Wakefield Suppression in a Manifold Damped and Detuned Structure for a 380 GeV CLIC Staged Design	wakefield, dipole, damping, accelerating-gradient	2980
	N.Y. Joshi, R.M. Jones UMAN, Manchester, United Kingdom
	The first stage of the Compact Linear Collider (CLIC) project aims to collide electrons and positrons at a 380 GeV center of mass energy. In the baseline design the main linacs for this staged approach are required to achieve a gradient of 72 MeV/m, with the surface electromagnetic fields (EM) and the transverse long-range wakefields bound by beam dynamics constraints. The baseline design utilizes heavy damping in a traveling wave (TW) structure. Here we report on an alternate design, which adopts moderate damping along with strong detuning of the individual cell frequencies. In the context of this Damped and Detuned Structure (DDS) design, we study Gaussian and hyperbolic secant dipole distributions, together with interleaving of successive structures, to effect long-range transverse wakefield suppression. Both analytic and modal summation approaches, in the quasi-coupled approximation, produce consistent results. In the optimisation scheme we opt for a dipole frequency bandwidth of 17.7 % (2.92 GHz)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB069
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPRB087	High-gradient SRF Cavity R&D at Cornell University	cavity, SRF, linear-collider, vacuum	3017
	M. Ge, T. Gruber, J.J. Kaufman, P.N. Koufalis, G. Kulina, M. Liepe, J.T. Maniscalco Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Achieving high accelerating field is a critical R&D topic for superconducting RF cavities for future accelerators including the International Linear collider (ILC). The ILC requires an average accelerating field of 35MV/m with a Q₀ of at least 8.9·10⁹ at 2K. In this paper, we report the latest results from high-gradient research at Cornell, which focusses on 75C vacuum baking to improve maximum (quench) fields. We demonstrate that such low temperature bakes can significantly improve quench fields in certain cases by mitigating localized defects. We further report on high-pulsed power results of these cavities before and after baking.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB087
About •	paper received ※ 23 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019
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WEPRB093	Design of a Proof-of-principle Crabbing Cavity for the Jefferson Lab Electron-ion Collider	cavity, electron, HOM, luminosity	3027
	H. Park, S.U. De Silva, J.R. Delayen, S.I. Sosa Guitron ODU, Norfolk, Virginia, USA J.R. Delayen, H. Park JLab, Newport News, Virginia, USA
	The Jefferson Lab design for an electron-ion collider (JLEIC) requires crabbing of the electron and ion beams in order to achieve the design luminosity. A number of options for the crabbing cavities have been explored, and the one which has been selected for the proof-of-principle is a 952 MHz, 2-cell rf-dipole (RFD) cavity. This paper summarizes the electromagnetic design of the cavity and its HOM characteristics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB093
About •	paper received ※ 22 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019
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WEPTS045	High-Performance Scheduling of Multi-Beam Multi-Bunch Simulations	simulation, wakefield, site, hadron	3208
	S.V. Furuseth, X. Buffat CERN, Geneva, Switzerland S.V. Furuseth EPFL, Lausanne, Switzerland
	Coherent multi-bunch interactions through beam-beam forces or wake fields can cause severe impacts on the beams in circular colliders, if not well understood and countered for. COMBI is a parallel multiparticle tracking code developed to study such interactions. Its implementation greatly limits its efficiency when considering realistic configurations featuring effects with different computational requirements, such as the multi-bunch interaction through wake fields, beam-beam interactions, transverse feedback and lattice non-linearities. A new parallel scheduling method, pipelining the effects for each bunch, has greatly sped up the code. The new version of the code, COMBIp, is presented here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS045
About •	paper received ※ 06 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPTS073	Beam-Beam Effect: Crab Dynamics Calculation in JLEIC	simulation, luminosity, electron, cavity	3293
	H. Huang, F. Lin, V.S. Morozov, Y. Roblin, A.V. Sy, Y. Zhang JLab, Newport News, Virgina, USA I. Neththikumara, S. Sosa, B. Terzić ODU, Norfolk, Virginia, USA
	The electron and ion beams of a future Electron Ion Collider (EIC) must collide at an angle for detection, machine and engineering design reasons. To avoid associated luminosity reduction, a local crabbing scheme is used where each beam is crabbed before collision and de-crabbed after collision. The crab crossing scheme then provides a head-on collision for beams with a non-zero crossing angle. We develop a framework for accurate simulation of crabbing dynamics with beam-beam effects by combining symplectic particle tracking codes with a beam-beam model based on the Bassetti-Erskine analytic solution. We present simulation results using our implementation of such a framework where the beam dynamics around the ring is tracked using Elegant and the beam-beam kick is modeled in Python.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS073
About •	paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPTS081	An Analytic Approach to Emittance Growth from the Beam-Beam Effect with Applications to the LHeC	proton, emittance, electron, GUI	3307
	E.A. Nissen JLab, Newport News, Virginia, USA D. Schulte CERN, Meyrin, Switzerland
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript. In colliders with asymmetric rigidity such as the proposed Large Hadron electron Collider, jitter in the weaker beam can cause emittance growth via coherent beam-beam interactions. The LHeC in this case would collide 7 TeV protons on 60 GeV electrons, which can be modeled using a weak-strong model. In this work we estimate the proton beam emittance growth by separating out the longitudinal angular kicks from an off-center bunch interaction and produce an analytic expression for the emittance growth per turn in systems like the LHeC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS081
About •	paper received ※ 01 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPTS082	Luminosity Studies of Asymmetric Crab Crossing in JLEIC	luminosity, ECR, electron, cavity	3311
	E.A. Nissen JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript. The proposed Jefferson Lab Electron Ion Collider (JLE-IC) currently plans to use a crab crossing scheme to max-imize the available luminosity. It had been suggested that space and cost savings, as well as hadron beam quality improvements, could be realized by leaving the ion beam un-crabbed and increasing the crabbing angle of the elec-tron beam. This and variations in-between equal and totally one-sided crabbing are examined for both JLEIC and LHC parameters, with various changes in crabbing angle and frequency studied to maximize luminosity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS082
About •	paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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WEPTS104	Synchrotron Radiation Reflections in the CLIC Beam Delivery System	photon, detector, synchrotron, radiation	3363
	D. Arominski, A. Latina, A. Sailer, D. Schulte CERN, Meyrin, Switzerland
	Synchrotron radiation (SR) reflection is an important issue for future linear colliders. High fluxes of the SR might impact the performance of the detector, through irradiation of the forward luminosity and beam quality calorimeters or of the innermost layers of the vertex detector. The photon reflections depend on the beam pipe apertures’ size, their shape, and materials used with various surface roughness. In this work, we present a study of SR including reflection for the 380 GeV and 3 TeV beam parameters and optics of the Compact Linear Collider’s Final Focus System. The simulations of the SR reflections using the Synrad+ software are presented and the impact on the detector is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS104
About •	paper received ※ 29 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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WEPTS108	Emittance Exchange in MICE	emittance, experiment, simulation, factory	3378
	C. Brown STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom C.G. Whyte USTRAT/SUPA, Glasgow, United Kingdom
	Funding: STFC, NSF, DOE, INFN, CHIPP and more The Muon Ionization Cooling Experiment, MICE, has demonstrated transverse emittance reduction through ionization cooling. Transverse ionization cooling can be used either to prepare a beam for acceleration in a neutrino factory or for the initial stages of beam cooling in a muon collider. Later stages of ionization cooling in the muon collider require the longitudinal emittance to be manipulated using emittance exchange and reverse emittance exchange, where emittance is exchanged from and to longitudinal phase space respectively. A wedge absorber within the MICE cooling channel has been used to experimentally demonstrate reverse emittance exchange in ionization cooling. Parameters for this test have been explored in simulation and applied to experimental configurations using a wedge absorber when collecting data in the MICE beam. This analysis of reverse emittance exchange is presented in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS108
About •	paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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THAPLM3	2019 Nishikawa Tetsuji Prize Talk	electron, proton, operation, experiment	3439
	V.D. Shiltsev Fermilab, Batavia, Illinois, USA
	For his original work on electron lenses in synchrotron colliders, his outstanding contribution to the construction and operation of high-energy, high-luminosity hadron colliders and for his tireless leadership in the accelerator community.
	Slides THAPLM3 [17.631 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THAPLM3
About •	paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPMP035	Tactile Collider : Accelerator Outreach to Visually Impaired Audiences	quadrupole, acceleration, detector, site	3518
	R.B. Appleby, B. Jeffrey, B.S. Kyle, T.H. Pacey, H. Rafique, S.C. Tygier, R. Watson UMAN, Manchester, United Kingdom T. Boyd, A.L. Healy Cockcroft Institute, Lancaster University, Lancaster, United Kingdom C.S. Edmonds Cockcroft Institute, Warrington, Cheshire, United Kingdom M.T. Hibberd The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
	Funding: STFC (UK) The Large Hadron Collider (LHC) has attracted significant attention from the general public. The science of the LHC and Higgs Boson is primarily communicated to school children and the wider public using visual methods. As a result, people with visual impairment (VI) often have difficulty accessing scientific communications and may be culturally excluded from news of scientific progress. Tactile Collider is a multi-sensory experience that aims to communicate particle accelerator science in a way that is inclusive of audiences with VI. These experiences are delivered as a 2-hour event that has been touring the UK since 2017. In this article we present the methods and training that have been used in implementing Tactile Collider as a model for engaging children and adults with science. The event has been developed alongside experts that specialise in making learning accessible to people with VI.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP035
About •	paper received ※ 09 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPGW055	Improving High Precision Cam Mover’s Stiffness	FEM, alignment, interface, experiment	3713
	J. Kemppinen ETH, Zurich, Switzerland H.M. Durand, A. Herty CERN, Meyrin, Switzerland
	Pre-alignment is a key challenge of the Compact Linear Collider (CLIC) study. The requirement for CLIC main beam quadrupole (MBQ) alignment is positioning to within 1 µm from target in 5 degrees of freedom (DOF) with ± 3 mm travel. After motion, the position should be kept passively while the system’s fundamental frequency is above 100 Hz. Cam movers are considered for the task. Traditionally they are used for the alignment of heavier magnets with lower accuracy and stiffness requirement. This paper presents a new CLIC prototype cam mover with design emphasis on the fundamental frequency. A finite element method (FEM) model predicts the mode shapes and eigenfrequencies of the system and can be used for further improving the design. Experimental modal analysis (EMA) of the prototype shows that the prototype’s fundamental frequency is at 44 Hz. It also validates the FEM model. Juha. Kemppinen@cern.ch
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW055
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THPRB073	Laboratory Measurements on Two ±12.5 kV Inductive Adders with ±0.02% Waveform Stability for CLIC Damping Ring Extraction Kickers	kicker, flattop, extraction, damping	3978
	J. Holma, M.J. Barnes, A. Chmielinska CERN, Geneva, Switzerland M. Pont ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	The CLIC study is investigating the technical feasibil-ity of an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. Pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. The DR kicker systems must provide extremely stable field pulses to avoid beam emittance increase. Each DR extrac-tion kicker system consists of a set of striplines and two pulse modulators. Specifications for this system require that the modulator produce pulses of 900 ns flattop dura-tion, ±12.5 kV and 305 A, with ripple and droop of not more than ±0.02 % (±2.5 V) with respect to a reference waveform. Inductive adder topology has been chosen for the pulse modulators. Two full-scale, 20-layer, 12.5 kV prototype inductive adders have been designed, built and tested at CERN. This paper presents the measurements of the stability of these adders for two different waveforms: a flat-top waveform and a controlled decay waveform, the latter of which is required to generate flat-top total field for the CLIC DR extraction stripline kicker.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB073
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THPRB096	Real-Time Beam Orbit Stabilisation to 200 Nanometres in Single-Pass Mode Using a High-Precision Dual-Phase Feedback System	feedback, extraction, electron, real-time	4049
	D.R. Bett, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan JAI, Oxford, United Kingdom
	A high-resolution, low-latency, stripline beam position monitor (BPM) system has been developed for use at particle accelerators and beamlines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system consists of fast analogue stripline BPM signal processors input to a custom FPGA-based digital feedback board which drives a pair of kickers local to the BPMs and nominally orthogonal in phase in closed-loop feedback mode, thus achieving both beam position and angle stabilisation. The feedback system was tested with the electron beam in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. Recent upgrades to the BPMs have increased the single-shot, real-time position resolution of the system to ~150 nm for a beam charge of 1.3 nC. We report the latest results which demonstrate the feedback system operating at this resolution limit and a beam stabilisation performance of 200 nm.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB096
About •	paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPRB113	Concept of Beam-Related Machine Protection for the Future Circular Collider	machine-protect, beam-losses, extraction, proton	4085
	Y.C. Nie, R. Schmidt, J.A. Uythoven, C. Wiesner, D. Wollmann, M. Zerlauth CERN, Meyrin, Switzerland
	In the Future Circular Collider (FCC) study, a proton-proton circular collider (FCC-hh) is considered with a stored beam energy 20 times higher than that of the LHC. Any uncontrolled release of such energy could potentially result in severe damage to the accelerator components. Machine protection of the FCC-hh is hence very important and challenging. With a machine-protection strategy similar to the LHC, FCC would require up to three turns to dump the beam synchronously after a failure detection. Due to several possible ultrafast failures, which could lead to significant beam losses in a few turns, it is important to further reduce the reaction time of the machine protection system (MPS) for the FCC. Reducing the detection time of a failure by using faster beam monitors, e.g. diamond detectors, can reduce the time between a beam loss and the beam dump request. Communication delay of the interlock system to the beam dumping system can be reduced by using a more direct signal path. More than one beam-free abort gap will shorten the time required for the synchronization between the abort gap and the extraction kicker. Different failure scenarios are classified according to the speed of the failure onset and the subsequent increase of induced beam losses. The critical failure modes, their potential mitigations and impacts on the design of the MPS are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB113
About •	paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPTS041	Progress and TDR Plans of the Mechanical System of CEPC	detector, alignment, vacuum, dipole	4200
	H. Wang, S. Bai, M.X. Li, Y.D. Liu, C. Meng, H. Qu, J.L. Wang, P. Zhang, N. Zhou IHEP, Beijing, People’s Republic of China
	The TDR of CEPC is aimed at the key science and technology problems and makes preparations for the real project. This paper will describe the progress of mechanical system including the regular supports and transport vehicle design, the mockup plan, the installation scenario of machine detector interface (MDI) and the movable collimator, as well as the TDR plans of mechanical system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS041
About •	paper received ※ 28 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPTS084	Magnet Design Optimization for Future Hadron Colliders	dipole, hadron, magnet-design, power-supply	4307
	V.V. Kashikhin, V. Lombardo, G. Velev Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. Fermilab in collaboration with other members of the US Magnet Development Program (MDP) is working on the development of accelerator magnets for future hadron colliders. A 4-layer, 15-T dipole with 60 mm aperture based on Nb₃Sn Low Temperature Superconductor (LTS) has been fabricated and tested. It is an important milestone of demonstrating readiness of the LTS magnet technology for the next generation of hadron colliders. At the same time, design studies aimed at boosting the magnet performance even further with the help of High Temperature Superconductors (HTS) are under way. This paper introduces a novel magnet technology - Conductor On Molded Barrel (COMB) optimized for the HTS materials and discusses possible steps towards its demonstration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS084
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPTS087	Micro-aligned Solenoid for Magnetized Bunched-beam Electron Cooling of 100 GeV/u Ions	electron, solenoid, alignment, GUI	4314
	P.M. McIntyre, J. Breitschopf, J. Gerity, J.N. Kellams Texas A&M University, College Station, USA J. Breitschopf, J. Gerity, J.N. Kellams, A. Sattarov ATC, College Station, Texas, USA
	Funding: This work is supported by grant DE-SC0018468 from the US Dept. of Energy. Magnetized electron cooling of ion beams requires pre-cise alignment of the electron beam with the equilibrium trajectory of the ion bunch. For the parameters required for JLEIC, a solenoid with bore field ~1 T, length ~30 m, and rms alignment of ~μrad is required. Such precise alignment has never been accomplished in a 1 T solenoid. The design of a micro-aligned solenoid is presented. A gap-separated stack of thin steel washers is located inside the solenoid. The washer stack shields transverse magnet-ic fields from its interior by a factor of ~10. A 30-washer module of the structure was built and measured using ultra-sensitive capacitive probes using a coordinate meas-uring machine. The r.m.s. coplanarity of the washer gaps was measured to be <5 μm, consistent with the required micro-alignment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS087

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MOYPLM3

Progress with the High Luminosity LHC Project at CERN

luminosity, cavity, operation, quadrupole

17

L. Rossi, O.S. Brüning
CERN, Geneva, Switzerland

The High Luminosity LHC (HL-LHC) project aims at upgrading the LHC by increasing the peak luminosity by a factor five, to allow to collect 3000 fb-1 for ATLAS and CMS experiments, each, which is ten times more than what is foreseen in the LHC. The upgrade is based on multiple factors. One factor is doubling the beam current, also thanks to the injector upgrade (LIU) project, and another one is operation in levelling mode. The most critical upgrade is the deploying of a stronger inner quadrupole triplet in the low-beta insertions with more than twice-larger aperture w.r.t. present LHC triplet, thanks to the use of Nb₃Sn superconductor, a world first for accelerators, with almost 12 T peak field in the coils. The novel concept of ATS optics allows to utilise the increased aperture efficiently by generating β^* values 3 to 4 times below the nominal values of the LHC. We will make use of compact crab cavities for hadrons (also a novelty in accelerators) to allow almost head-on collisions despite the larger crossing angle. We are developing new collimator insertions in the dispersion suppressor region to handle the losses in the cold part of the machine (the beam halo stores 30 MJ) thanks to the use of a few 11 T dipoles based on Nb₃Sn technology. We also aim at reducing drastically the impedance contribution of collimators by utilizing new materials and coating techniques. Many other technologies are developed for HL-LHC like new SC links of 100 kA: HL-LHC is critical as a technology turning point for HEP colliders as it is for Physics reach. The technologies developed for HL-LHC, namely (but not only) the high field superconducting magnets, are critical for the post-LHC hadron collider, like a High Energy LHC or the 100 km Future Circular Collider

Slides MOYPLM3 [21.679 MB]

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MOZPLS2

Ion Collider Precision Measurements With Different Species

target, operation, electron, experiment

28

G.J. Marr, E.N. Beebe, I. Blackler, W. Christie, K.A. Drees, P.S. Dyer, A.V. Fedotov, W. Fischer, C.J. Gardner, H. Huang, T. Kanesue, N.A. Kling, V. Litvinenko, C. Liu, Y. Luo, D. Maffei, B. Martin, A. Marusic, K. Mernick, M.G. Minty, C. Naylor, M. Okamura, I. Pinayev, G. Robert-Demolaize, T. Roser, P. Sampson, V. Schoefer, T.C. Shrey, D. Steski, P. Thieberger, J.E. Tuozzolo, K. Zeno, I.Y. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Precedent to electron cooling commissioning and collisions of Gold at various energies at RHIC in 2018, the STAR experiment desired an exploration of the chiral magnetic effect in the quark gluon plasma (QGP) with an isobar run, utilizing Ruthenium and Zirconium. Colliding Zr-96 with Zr-96 and Ru-96 with Ru-96 create the same QGP but in a different magnetic field due to the different charges of the Zr (Z=40) and Ru (Z=44) ions. Since the charge difference is only 10%, the experimental program requires exacting store conditions for both ions. These systematic error concerns presented new challenges for the Collider, including frequent reconfiguration of the Collider for the different ion species, and maintaining level amounts of instantaneous and integrated luminosity between two species. Moreover, making beams of Zr-96 and Ru-96 is challenging since the natural abundances of these isotopes are low. Creating viable enriched source material for Zr-96 required assistance processing from RIKEN, while Ru-96 was provided by a new enrichment facility under commissioning at Oak Ridge National Laboratory.

Slides MOZPLS2 [4.758 MB]

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MOZZPLS2

Positron Driven Muon Source for a Muon Collider: Recent Developments

target, emittance, damping, positron

49

M.E. Biagini, M. Antonelli, O.R. Blanco-García, M. Boscolo, A. Ciarma, A. Giribono, S. Guiducci, C. Vaccarezza, A. Variola
INFN/LNF, Frascati, Italy
A. Bacci
INFN-Milano, Milano, Italy
M. Bauce, F. Collamati
INFN-Roma1, Rome, Italy
G. Cesarini
INFN-Roma, Roma, Italy
I. Chaikovska, R. Chehab
LAL, Orsay, France
S.M. Liuzzo, P. Raimondi
ESRF, Grenoble, France
D. Lucchesi
Univ. degli Studi di Padova, Padova, Italy
N. Pastrone
INFN-Torino, Torino, Italy

The design of a future multi-TeV muon collider needs new ideas to overcome the technological challenges related to muon production, cooling, accumulation and acceleration. The Low Emittance Muon Accelerator (LEMMA) concept *,** presents in this paper an upgraded layout of a positron driven muon source. The positron beam, stored in a ring with high energy acceptance and low emittance, is extracted and driven in a push-pull configuration to a multi-target system, to produce muon pairs at threshold on the target’s electrons. This solution alleviates the issues related to the power deposited and the integrated Peak Energy Density Deposition on the targets. Muons produced in the multi-target system will then be accumulated in many parallel rings before acceleration and injection in the collider. A special multi-target line lattice has been designed to cope with the focusing of both the positron and muon beams. Studies on the number, material and thickness of the targets have been carried out. A general layout of the overall scheme and a description is presented, as well as plans for future R&D.
* M. Antonelli, P. Raimondi, INFN-13-22/LNF, 2013
** M. Boscolo, M. Antonelli, O.R. Blanco-Garcia, S. Guiducci, S. Liuzzo, P. Raimondi, F. Collamati, Phys. Rev. Accel. Beams, vol. 21, p. 061005, 2018

Slides MOZZPLS2 [4.360 MB]

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MOPGW051

Diffusion Map Analysis in High Energy Storage Ring Based e⁺/e⁻ Collider

dynamic-aperture, radiation, synchrotron-radiation, synchrotron

203

J. Wu, Q. Qin, Y. Zhang
IHEP, Beijing, People’s Republic of China
J. Wu, Y. Zhang
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

Funding: Project 11775238 supported by NSFC
In a very high energy e⁺/e⁻ storage ring collider, e.g. Circular Electron Positron Collider (CEPC), the dynamic aperture is limited by the strong synchrotron radiation especially in the vertical direction. Some tracking results also shows that the beam lifetime does not correspond well to the dynamic aperture. Here we develop a method called diffusion map analysis, aiming to describe the beam distribution diffusion in transverse amplitude space by tracking less turns. The diffusion may come from quantum fluctuation of SR, beamstrahlung effect and nonlinearity. Comparing cases with different configuration of sextupoles, the diffusion map analysis presents good consistency with beam lifetime that needs much more turns of tracking. Constraints based on the diffusion map is applied to our dynamic aperture optimization, which could help us achieve enough long beam lifetime.

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MOPGW068

Crosstalk of Beam-Beam Effect and Longitudinal Impedance at CEPC

impedance, simulation, luminosity, factory

247

Y. Zhang, N. Wang, C.H. Yu
IHEP, Beijing, People’s Republic of China
C.T. Lin
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

Funding: Project 11775238 supported by NSFC
In conventional e⁺e⁻ storage ring colliders, we only use lengthend bunch length in beam-beam simulation instead of considering impedance directly. It is no problem since the longitudinal dynamics is not sensitive to beam-beam interaction. But it is different since the bunch will also be lengthend during beam-beam interaction by beamstrahlung effect. It is very natural and more self-consistent to consider the longitudinal impedance in the beam-beam simulation. The simulation shows that the working point region of stable collision is slightly shifted by the longitudinal impedance. It is found that the vertical coherent oscillation may decreases the beam-beam limit with impedance at some working point.

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MOPGW071

Resistive Wall Effects in the CLIC Beam Delivery System

luminosity, wakefield, vacuum, feedback

258

D. Arominski, A. Latina, D. Schulte
CERN, Meyrin, Switzerland

Resistive wall wakefields are an important issue to study for future linear colliders. Wakefields in the Beam Delivery System (BDS) might cause severe multi-bunch effects, leading to beam quality and luminosity losses. The resistive wall effects depend on the beam pipe apertures and materials, which are optimised to limit the impact on the beam. This paper presents a study of this problem for the 380 GeV and 3 TeV beam parameters and optics of the Compact Linear Collider’s BDS. First, the optimisation of the beam pipe apertures to limit the impact of resistive wall effect on the beam quality is shown, then the luminosity and its quality are presented. Finally, the proposed design parameters are discussed.

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MOPGW081

Measurements of Stray Magnetic Fields at CERN for CLIC

klystron, site, proton, dipole

289

C. Gohil, N. Blaskovic Kraljevic, D. Schulte
CERN, Meyrin, Switzerland
P. Burrows
JAI, Oxford, United Kingdom
B. Heilig
MFGI, Budapest, Hungary

Simulations have shown that the Compact Linear Collider (CLIC) is sensitive to external dynamic magnetic fields (stray fields) to the nT level. Magnetic fields are not typically measured to this precision at CERN. Past measurements of the background magnetic field at CERN are limited. In this paper new measurements are presented.

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MOPGW082

Mitigation of Stray Magnetic Field Effects in CLIC with Passive Shielding

shielding, feedback, simulation, hadron

293

C. Gohil, N. Blaskovic Kraljevic, D. Schulte
CERN, Meyrin, Switzerland
P. Burrows
JAI, Oxford, United Kingdom

Simulations have shown the Compact Linear Collider (CLIC) is sensitive to external dynamic magnetic fields (stray fields) to the nT level. Due to these extremely tight tolerances, mitigation techniques will be required to prevent performance loss. A passive shielding technique is envisaged as a potential solution. A model for passive shielding is presented along with calculations of its transfer function. Measurements of the transfer function of a promising material (mu-metal) that can be used for passive shielding are presented. The validity of passive shielding models in small amplitude magnetic fields is also discussed.

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MOPGW084

Beam Loading Compensation for the Future Circular Hadron-Hadron Collider (FCC-hh)

cavity, beam-loading, hadron, impedance

301

I. Karpov, P. Baudrenghien
CERN, Meyrin, Switzerland

The power consumption of the rf system can be minimised by optimising the cavity detuning and the loaded quality factor. In high-current accelerators, the presence of gaps in the filling results in a modulation of the cavity voltage along the ring (transient beam loading) and as a consequence a spread in the bunch parameters. In addition longitudinal coupled-bunch instabilities can appear, caused by the cavity impedance at the fundamental. Both issues can be mitigated by using an rf feedback around the amplifier and cavity, a technique used in many high intensity machines including the Large Hadron Collider (LHC). Compared to the LHC machine, the energy increase and the radiation loss for the Future Circular hadron-hadron Collider (FCC-hh) will be larger, resulting in a synchronous phase deviating significantly from 180 degrees. The solutions adopted for the LHC must therefore be revisited. This paper evaluates several beam loading compensation schemes for this machine.

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MOPGW085

Intensity Dependent Effects in the ILC BDS

wakefield, luminosity, simulation, linear-collider

305

P. Korysko, A. Latina
CERN, Geneva, Switzerland
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

The International Linear Collider (ILC) is an electron-positron collider being considered for the post-LHC era. Its Beam Delivery System (BDS) receives the beam from the main linac. This beam is then focused to the nanometer scale after going through collimators, beam diagnostic systems, strong magnets, etc. Effects such as wakefields due to resistive-wall, BPMs and collimators make the system very sensitive to the beam intensity. Understanding these effects is crucial in order to demonstrate that the nominal beam size at the Interaction Point (IP) can be reached in realistic scenarios. In this paper, results of the intensity dependence effects in the ILC BDS, simulated with PLACET, are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW085

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paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW086

Intensity Dependent Effects at ATF2, KEK

simulation, linear-collider, wakefield, electron

308

P. Korysko, A. Latina
CERN, Geneva, Switzerland
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
A. Faus-Golfe
LAL, Orsay, France
K. Kubo, T. Okugi
KEK, Ibaraki, Japan

The Accelerator Test Facility 2 (ATF2) at KEK is a prototype for the Final Focus Systems of the future e⁺e⁻ linear colliders, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). In this paper both simulation and experimental results are presented with special emphasis on intensity-dependent effects. The importance of these effects is shown using the PLACET code and realistic ATF2 machine simulations (including beam jitter, misalignment, wakefield, Beam Based Alignment (BBA) correction, …). The latest experimental results are also presented, in particular the impact of the beam intensity on the beam size at the IP.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW086

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paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP003

Positron Source for FCC-ee

positron, target, linac, electron

424

I. Chaikovska, R. Chehab, A. Faus-Golfe, Y. Han
LAL, Orsay, France
A. Apyan
ANSL, Yerevan, Armenia
Y. Enomoto, K. Furukawa, T. Kamitani, F. Miyahara, M. Satoh, Y. Seimiya, T. Suwada
KEK, Ibaraki, Japan
P.V. Martyshkin
BINP SB RAS, Novosibirsk, Russia
S. Ogur, K. Oide, Y. Papaphilippou, L. Rinolfi, P. Sievers, F. Zimmermann
CERN, Geneva, Switzerland

The FCC-ee is a high-luminosity, high-precision circular collider to be constructed in a new 100 km tunnel in the Geneva area. The physics case is well established and the FCC-ee operation is foreseen at 91 GeV (Z-pole), 160 GeV (W pair production threshold), 240 GeV (Higgs resonance) and 365 GeV (t-tbar threshold). Due to the large 6D production emittance and important thermal load in the production target, the positron injector, in particular the positron source, is one of the key elements of the FCC-ee, requiring special attention. To ensure high reliability of the positron source, conventional and hybrid targets are currently under study. The final choice of the positron target will be made based on the estimated performances. In this framework, we present a preliminary design of the FCC-ee positron source, with detailed simulation studies of positron production, capture and primary acceleration.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP003

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paper received ※ 03 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP005

Field Quality for the Hadron Option of Future Circular Collider

injection, dipole, octupole, target

4397

B. Dalena, D. Boutin
CEA-IRFU, Gif-sur-Yvette, France
A. Chancé
CEA-DRF-IRFU, France
E. Cruz Alaniz
The University of Liverpool, Liverpool, United Kingdom
D. Schulte
CERN, Meyrin, Switzerland

Funding: This Research and Innovation Action project submitted to call H₂020-INFRADEV-1-2014-1 receives funding from the European Union’s H₂020 Framework Program under grant agreement No. 654305.
The updated field quality for the baseline design option of the Nb₃Sn dipoles for Future Circular Collider (FCC-hh) is discussed. The impact on the expected dynamic aperture is shown at injection and collision energy and the consequent non-linear correction schemes together with their integration in the optics are defined.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP005

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP007

Design of a Compact Power Distribution System for the ILC

cavity, cryomodule, ECR, acceleration

436

B. Du, N. Liu
Sokendai - Hayama, Hayama, Japan
T. Matsumoto, S. Michizono, T. Miura, F. Qiu
KEK, Ibaraki, Japan
T. Matsumoto, T. Miura, F. Qiu
Sokendai, Ibaraki, Japan

The Local power distribution system (LPDS) of the In-ternational Linear Collider (ILC) is constructed to transmit RF power from the 10 MW klystron to 39 cavi-ties. Each eight or nine 9-cell cavities is assembled in one cryomodule. The variable hybrid is used to adjust the power dividing ratio due to the different required power of each cavity and the variable phase shifter is used to compensate the phase drift caused by the variable hybrid. More compact LPDS is expected to be integrated on the cryomodule decreasing financial cost. We re-design the shorter variable hybrid with a margin of power ratio of ±25% and phase shifter of total phase range being 35° for compensating hybrid and on-crest searching. Fixed phase shifters are designed to adjust the phase difference between adjacent cavities for beam acceleration. Simu-lated results of total compact LPDS can meet the re-quirements of ILC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP007

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paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP009

Effect of Initial Parameters on the Super Flat Beam Generation with the Phase-Space Rotation for Linear Colliders

emittance, simulation, gun, solenoid

442

M. Kuriki, R. Tamura
HU/AdSM, Higashi-Hiroshima, Japan
H. Hayano, X.J. Jin, T. Konomi, Y. Seimiya, N. Yamamoto
KEK, Ibaraki, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J.G. Power
ANL, Argonne, Illinois, USA
K. Sakaue
The University of Tokyo, The School of Engineering, Tokyo, Japan
M. Washio
RISE, Tokyo, Japan

Funding: This work is partly supported by Japan-US Cooperative grant for scientific studies, Grant aid for scientific study by MEXT Japan (KAKENHI) Kiban B.
Linear collider is a concept to realize e⁺e⁻ collision beyond the limitation of the ring colliders by the synchrotron radiation. To obtain an enough luminosity, eg. 1.0·10⁺³⁴ cm^-2sec^-1, the beam is focused down to nano-meter size with a high aspect ratio. This super flat beam is useful to improve the luminosity and to compensate the beam-beam effect, eg. Beamstrahlung. In a conventional design, the super-flat beam is produced by radiation damping in a storage ring. We propose to produce this super-flat beam with phase-space rotation techniques. We employ both Round to Flat Beam Transformation and Transverse to Longitudinal Emittance eXchange, the super flat beam can be generated by controlling the space-charge effect which spoiled the performance. We present the RFBT performance with respect to the initial conditions, i.e. beam size, initial emittance, solenoid field (strength and profile), etc.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP009

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paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP014

NICA Accelerator Complex at JINR

booster, dipole, proton, injection

452

E. Syresin, O.I. Brovko, A.V. Butenko, E.E. Donets, A.R. Galimov, E.V. Gorbachev, A. Govorov, V. Karpinsky, V. Kekelidze, H.G. Khodzhibagiyan, S.A. Kostromin, A.D. Kovalenko, O.S. Kozlov, I.N. Meshkov, A.V. Philippov, A.O. Sidorin, V. Slepnev, A.V. Smirnov, G.V. Trubnikov, A. Tuzikov, V. Volkov
JINR, Dubna, Moscow Region, Russia

Status of the project of NICA accelerator complex, which is under construction at JINR (Dubna, Russia), is presented. The main goal of the project is to provide ion beams for experimental studies of hot and dense baryon-ic matter and spin physics. The NICA collider will pro-vide heavy ion collisions in the energy range of √sNN=4/11 GeV at average luminosity of L=1.1027cm−2·s−1 for 197Au⁷⁹⁺ nuclei and polarized proton collisions in energy range of √sNN=12/27 GeV at lumi-nosity of L ≥ 1031cm−2·s⁻¹. NICA accelerator complex will consist of two injector chains, 578 MeV/u supercon-ducting (SC) booster synchrotron, the existing SC syn-chrotron (Nuclotron), and the new SC collider that has two storage rings each of 503 m circumference. Con-structing facility is based on Nuclotron-technology of SC magnets with iron yoke. Hollow SC cable cooled by two-phase He-flux used for operation with 10 kA currents and 1Hz cycling rate. Both stochastic and electron cooling methods are used for the beam accumulation and its stability maintenance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP014

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paper received ※ 29 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP015

Longitudinal Particle Dynamics in NICA Collider

bunching, injection, accumulation, acceleration

455

E. Syresin, A.V. Eliseev, A.V. Smirnov
JINR, Dubna, Moscow Region, Russia
N.V. Mityanina, V.M. Petrov, E. Rotov, A.G. Tribendis
BINP SB RAS, Novosibirsk, Russia

A specific feature of the NICA acceleration complex is high luminosity of colliding beams. Three types of RF stations will be used in the NICA Collider to reach the necessary beam parameters. The first one is for accumulation of particles in the longitudinal phase space with the moving burrier buckets under action of stochastic and/or electron cooling systems. The second and third RF stations are for formation of the final bunch size in the colliding regime. This report presents numerical simulations of longitudinal beam dynamics which taken into account the longitudinal space charge effect during the accumulation and bunching procedures. Influence of space effects leads to some decrease in the accumulation efficiency and requires special manipulation with the 2nd and 3rd RF stations during the adiabatic capture and bunching procedures.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP015

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paper received ※ 29 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP016

Intra-Bunch Energy Spread Minimisation for CLIC Operation at a Centre-of-Mass Energy of 350 GeV

linac, luminosity, emittance, linear-collider

458

N. Blaskovic Kraljevic, D. Arominski, D. Schulte
CERN, Meyrin, Switzerland

The first stage of the electron-positron Compact Linear Collider (CLIC) is designed with a centre-of-mass energy of 380 GeV. A dedicated threshold scan in the vicinity of 350 GeV is envisioned with a total integrated luminosity of 100 fb^-1. This scan calls for a very small intra-bunch energy spread in order to achieve an excellent collision energy resolution. This paper presents an optimised assignment of RF accelerating gradients and phases in the CLIC main linac for operation at 350 GeV, which minimises the energy spread at the end of the main linac whilst preserving a small emittance growth. Variation of the bunch length and charge is studied in order to further reduce the energy spread; the effect on both the peak and total luminosity is discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP016

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paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP017

Beam Orbit Correction in the CLIC Main Linac Using a Small Subset of Correctors

linac, emittance, quadrupole, ground-motion

461

N. Blaskovic Kraljevic, D. Schulte
CERN, Meyrin, Switzerland

Beam orbit correction in future linear colliders, such as the Compact Linear Collider (CLIC), is essential to mitigate the effect of accelerator element misalignment due to ground motion. The correction is performed using correctors distributed along the accelerator, based on the beam position monitor (BPM) readout from the preceding bunch train, with a train repetition frequency of 50 Hz. This paper presents the use of the MICADO algorithm* to select a subset of N ~ 10 correctors (from a total of 576) to be used for orbit correction in the designed 380 GeV centre-of-mass energy first-stage of CLIC. The optimisation of the number N of correctors, the algorithm’s gain and the corrector step size is described, and the impact of a number of BPMs and correctors becoming unavailable is addressed. The application of a MICADO algorithm to perform dispersion free steering, by reducing the beam orbit difference between two beams with different energies, is discussed.
* B. Autin & Y. Marti, "Closed orbit correction of A.G. machines using a small number of magnets", CERN-ISR-MA/73-17, 1973.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP017

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paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP018

Beam-Based Beamline Element Alignment for the Main Linac of the 380 GeV Stage of CLIC

emittance, linac, alignment, wakefield

465

N. Blaskovic Kraljevic, D. Schulte
CERN, Meyrin, Switzerland

The extremely small vertical beam size required at the interaction point of future linear colliders, such as the Compact Linear Collider (CLIC), calls for a very small vertical emittance. The strong wakefields in the high frequency 12 GHz CLIC accelerating structures set tight tolerances on the alignment of the main linac’s beamline elements and on the correction of the beam orbit through them in order to mantain a small emittance growth. This paper presents the emittance growth due to each type of beamline element misalignment in the designed 380 GeV centre-of-mass energy first-stage of CLIC, and the emittance growth following a series of beam-based alignment (BBA) procedures. The BBA techniques used are one-to-one steering, followed by dispersion free steering and finally accelerating structure alignment using wakefield monitors.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP018

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paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP022

K-Modulation in Future High Energy Colliders

quadrupole, luminosity, optics, power-supply

476

M. Hofer, F.S. Carlier, R. Tomás
CERN, Geneva, Switzerland

K-Modulation of the quadrupoles closest to the interaction point (IP) has been an indispensable tool to accurately measure the beta-function in the interaction point (β^*) in the Large Hadron Collider (LHC) at CERN. K-Modulation may become even more important to control the lower β^* and reach the design luminosities in the High-Luminosity LHC (HL-LHC) and the Future Circular Collider (FCC). K-Modulation results also provide important input for the luminosity calibration and help in the identification and correction of errors in the machines. This paper presents a method for determining β^* using K-Modulation adapted to the characteristic layout of both colliders. Using the latest models for the HL-LHC and the FCC-hh, estimated uncertainties on the measurements are presented. The results are compared to the accuracy of an alternative modulation scheme using a different powering scheme.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP022

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paper received ※ 06 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPMP023

Dynamic Aperture at Injection Energy for the HE-LHC

dipole, injection, lattice, dynamic-aperture

480

M. Hofer, M. Giovannozzi, J. Keintzel, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
L. van Riesen-Haupt
JAI, Oxford, United Kingdom

As part of the Future Circular Collider study, the High Energy LHC (HE-LHC) is a proposed hadron collider situated in the already existing LHC tunnel. It aims at achieving a center of mass energy of 27 TeV, almost doubling the design c.o.m. energy of the LHC. This increase in energy relies on the use of 16 T Nb₃Sn dipoles to be developed for the FCC-hh. The field quality of these dipoles is expected to have a big impact on the Dynamic Aperture (DA) at injection energy and subsequently tracking studies are conducted to evaluate the impact of magnetic field errors on the beam dynamics. In the following the results of these studies for the different injection energies considered for the HE-LHC are presented and a possible strategy for increasing the DA are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP023

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paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP025

Moving Long-range Beam-beam Encounters in Heavy-ion Colliders

proton, emittance, injection, acceleration

488

M.A. Jebramcik, J.M. Jowett
CERN, Geneva, Switzerland

Asymmetric ion beam collisions like proton-lead in the LHC or gold-deuteron in RHIC have become major components of heavy-ion physics programmes. The injection and ramp of two different ion species with the same magnetic rigidity and consequently unequal revolution frequencies generate moving long-range beam-beam encounters in the interactions regions of the collider. These encounters led to fast beam losses and can cause emittance blow-up as observed in RHIC in the early 2000s and, more recently, in 2015. Yet such effects are absent at the LHC so the difference between the two colliders requires explanation. Tools and models have been developed to describe the beam dynamics of moving long-range beam-beam encounters and to predict the evolution of emittance and other beam parameters. Besides presenting results for RHIC and the LHC we give an outlook for the HL-LHC and potential operational restrictions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP025

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paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPMP029

Analysis on Bunch-by-Bunch Beam Losses at 6.5 TeV in the Large Hadron Collider

luminosity, betatron, beam-losses, operation

500

K. Paraschou, G. Iadarola, N. Karastathis, S. Kostoglou, Y. Papaphilippou, L. Sabato
CERN, Geneva, Switzerland
S. Kostoglou
National Technical University of Athens, Zografou, Greece
K. Paraschou
AUTH, Thessaloniki, Greece

In 2018, a large fraction of the physics data taking at the Large Hadron Collider has been performed with a beam energy of 6.5 TeV, the nominal bunch spacing of 25 ns and beta functions at the high luminosity interaction points of 30 cm. In order to maximize the integrated luminosity, the crossing angles are gradually reduced as the beam intensity reduces due to luminosity burn-off. In these conditions the beam lifetime is visibly affected by collective effects and in particular by beam-beam interaction and electron cloud effects. By analyzing the beam losses at a bunch-by-bunch level, it is possible to disentangle the contributions from different effects and to assess the impact on the losses of changes applied to the machine configuration.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP029

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paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP034

Tuning Studies of the CLIC 380 Gev Final Focus System

sextupole, luminosity, alignment, linear-collider

512

J. Ögren, A. Latina, D. Schulte, R. Tomás
CERN, Meyrin, Switzerland

We present tuning studies of the Compact Linear Collider final-focus system under static imperfections including transverse misalignments, roll errors and magnetic strength errors. The tuning procedure consists of beam-based alignment for correcting the linear part of the system followed by sextupole pre-alignment and use of multipole tuning knobs. The sextupole pre-alignment is very robust and allows the tuning time to be greatly reduced.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP034

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paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP035

Effect of Emittance Constraints on Monochromatization at the Future Circular e⁺e⁻ Collider

emittance, luminosity, radiation, photon

516

M.A. Valdivia García, F. Zimmermann
CERN, Meyrin, Switzerland

Direct s-channel Higgs production in e+e− collisions is of interest if the collision energy spread can be comparable to the natural width of the standard model Higgs boson. At the Future Circular e⁺e⁻ Collider (FCC-ee), a monochromatization scheme could be employed in order to reduce the collision energy spread to the target value. This may be achieved by introducing a non-zero horizontal dispersion of opposite sign for the two colliding beams at the interaction point. In this case, the beamstrahlung increases the horizontal emittance in addition to energy spread and bunch length. The vertical emittance could either be tuned to a certain minimum value, possibly limited by the diagnostics resolution, or it could scale linearly with the horizontal emittance. For the FCC-ee at 62.5 GeV beam energy, we optimize the IP optics and beam parameters, considering these two different assumptions for the vertical emittance. We derive the maximum achievable luminosity as a function of collision energy spread for either case.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP035

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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MOPMP038

Investigation of CLIC 380 GeV Post-Collision Line

simulation, site, dipole, linear-collider

528

R.M. Bodenstein, A. Abramov, S.T. Boogert, P. Burrows, L.J. Nevay
JAI, Oxford, United Kingdom
D. Schulte, R. Tomás
CERN, Meyrin, Switzerland

It has been proposed that the Compact Linear Collider (CLIC) be commissioned in stages, starting with a lower-energy, 380 GeV version for the first stage, and concluding with a 3 TeV version for the final stage. In the Conceptual Design Report (CDR) published in 2012, the post-collision line is described for the 3 TeV and 500 GeV stages. However, the post-collision line for the 380 GeV design was not investigated. This work will describe the simulation studies performed in BDSIM for the 380 GeV post-collision line.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP038

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paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPMP048

LHC Doubler: CIC Dipole Technology May Make It Feasible and Affordable

dipole, multipole, injection, hadron

552

P.M. McIntyre
Texas A&M University, College Station, USA
J. Breitschopf, J.N. Kellams, A. Sattarov
ATC, College Station, Texas, USA
D.C.V. Chavez
Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico

There is new physics-driven interest in the concept of an LHC doubler with collision energy of 30 TeV and high luminosity. The cost-driver challenge for its feasibility is the ring of 16 T dual dipoles. Recent developments in cable-in-conduit (CIC) technology offer significant benefit for this purpose. The CIC windings provide robust stress management at the cable level and facilitate forming of the flared ends without degradation. The CIC windings provide a basis for hybrid windings, in which the innermost layers that operate in high field utilize Bi-2212, the center layers utilize Nb₃Sn, and the outer layers utilize NbTi. Cryogen flows through the interior of all cables, so that heat transfer can be optimized throughout the windings. The design of the 18 T dipole and the 23 kA CIC conductor will be presented. Particular challenges for integration in an LHC doubler will be discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP048

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paper received ※ 18 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPMP049

6 T Cable-in-conduit Dipole to Double the Ion Energy for JLEIC

dipole, electron, injection, luminosity

556

P.M. McIntyre, J. Breitschopf, J. Gerity
Texas A&M University, College Station, USA
J. Breitschopf, D.C.V. Chavez, J.N. Kellams, A. Sattarov
ATC, College Station, Texas, USA

The proposed electron-ion collider JLEIC would make high-luminosity collisions of polarized ions and polarized electrons with electron energy up to 12 GeV and ion energy up to 40 GeV/u. Both the luminosity and the collision energy could be increased by doubling the dipole field in the ion ring from 3 T to 6 T, and the enhanced performance would access the full range of parameters for the physics objectives of the project. The Texas A&M group has developed the large-aperture 3 T dipoles for the baseline project, based upon a novel superconducting cable-in-conduit. (CIC). A closely similar 6 T design is being developed, utilizing a 2-layer CIC. Details of the magnet design and development of the 2-layer CIC will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP049

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paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPMP053

Numerical Optimization of DC Wire Compensation in HL-LHC

operation, luminosity, hadron, simulation

570

K. Skoufaris, S.D. Fartoukh, N. Karastathis, Y. Papaphilippou, D. Pellegrini, A. Poyet, A. Rossi, G. Sterbini
CERN, Meyrin, Switzerland

The electromagnetic field generated from a set of DC wires parallel to the beam opens the path to the compensation of the beam-beam long-range (BBLR) interactions for the future operation of large hadron colliders, in particular for the upcoming High Luminosity upgrade of the Large Hadron Collider (HL-LHC). The effectiveness and simplicity of a current carrying wire are critical for overcoming some technical constraints of the machine. In order to better understand the potential of this device for the HL-LHC, various simulation studies are presented. The different observables are the dynamic aperture and the frequency analysis.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP053

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paper received ※ 03 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB031

Progress of Conceptual Study for the Accelerators of a 2-7GeV Super Tau Charm Facility at China

luminosity, factory, electron, operation

643

Q. Luo, W. Li, D.R. Xu
USTC/NSRL, Hefei, Anhui, People’s Republic of China
W.W. Gao, J.Q. Lan
Fujian University of Technology, Fuzhou, People’s Republic of China

Funding: Supported by National Natural Science Foundation of China U1832169 and the Double Fist-Class University Project Foundation of USTC.
This paper shows the progress of the conceptual study for the accelerators of a super tau charm facility in China. Since the BEPCII will finish its historical mission in 5~10 years and its upgrade plan will only achieve a small luminosity enhancement of 3~5 times, a new next generation tau-charm collider will play an irreplaceable role in future high energy physics study. The luminosity of this successor is about 5×10³⁴cm⁻²s⁻¹ pilot and 1×10³⁵cm⁻²s⁻¹ nominal, with the electron beam longitudinally polarized at the IP. The general scheme of the accelerators and the beam pa-rameters are shown. Several key technologies such as beam polarization and beam emittance diagnostics are also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB031

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paper received ※ 14 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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MOPRB041

Spin Resonance Strength in the Transparent Spin Mode of the NICA Collider

polarization, solenoid, resonance, proton

656

Y. Filatov, S.V. Vinogradov
MIPT, Dolgoprudniy, Moscow Region, Russia
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia
A.D. Kovalenko
JINR, Dubna, Moscow Region, Russia

To implement the polarization program at the NICA complex (Dubna, Russia) the novel mode of ion polarization control - the transparent spin mode - is planned to use. To set up the transparent spin mode in the NICA collider two solenoidal snakes will be placed in straights of the Multi Purpose Detector (MPD) and the Spin Physics Detector (SPD). The beam polarization at SPD will be controlled by means of ‘‘weak’’ solenoids. The main characteristic of the transparent spin mode is the spin resonance strength, which consists of two parts: a coherent part arising due to additional transverse and longitudinal fields on the beam trajectory deviating from the design orbit and an incoherent part associated with the particles’ betatron and synchrotron oscillations (beam emittances). The resonance strength allows one to formulate requirements on the magnitudes of the control solenoids’ fields. The theoretical analysis, calculation and spin tracking simulation of the spin resonance strength in the whole momentum range of the NICA collider are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB041

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paper received ※ 01 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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MOPRB048

Collimation System Studies for the FCC-hh

collimation, proton, simulation, hadron

669

R. Bruce, A. Abramov, A. Bertarelli, M.I. Besana, F. Carra, F. Cerutti, M. Fiascaris, G. Gobbi, A.M. Krainer, A. Lechner, A. Mereghetti, D. Mirarchi, J. Molson, M. Pasquali, S. Redaelli, D. Schulte, E. Skordis, M. Varasteh Anvar
CERN, Geneva, Switzerland
A. Abramov
JAI, Egham, Surrey, United Kingdom
A. Faus-Golfe
LAL, Orsay, France
M. Serluca
IN2P3-LAPP, Annecy-le-Vieux, France

The Future Circular Collider (FCC-hh) is being designed as a 100 km ring that should collide 50 TeV proton beams. At 8.3 GJ, its stored beam energy will be a factor 28 higher than what has been achieved in the Large Hadron Collider, which has the highest stored beam energy among the colliders built so far. This puts unprecedented demands on the control of beam losses and collimation, since even a tiny beam loss risks quenching superconducting magnets. We present in this article the design of the FCC-hh collimation system and study the beam cleaning through simulations of tracking, energy deposition, and thermo-mechanical response. We investigate the collimation performance for design beam loss scenarios and potential bottlenecks are highlighted.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB048

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paper received ※ 18 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB049

Study of Beam-Gas Interactions at the LHC for the Physics Beyond Colliders Fixed-Target Study

target, proton, experiment, simulation

673

C. Boscolo Meneguolo, R. Bruce, F. Cerutti, M. Ferro-Luzzi, M. Giovannozzi, A. Mereghetti, J. Molson, S. Redaelli
CERN, Geneva, Switzerland
A. Abramov
JAI, Egham, Surrey, United Kingdom

Among several working groups formed in the framework of Physics Beyond Colliders study, launched at CERN in September 2016, there is one investigating specific fixed-target experiment proposals. Of particular interest is the study of high-density unpolarized or polarized gas target to be installed in the LHCb detector, using storage cells to enhance the target density. This work studies the impact of the interactions of 7 TeV proton beams with such gas targets on the LHC machine in terms of particle losses.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB049

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paper received ※ 17 April 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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MOPRB051

Collimation System Upgrades for the High Luminosity Large Hadron Collider and Expected Cleaning Performance in Run 3

collimation, proton, hadron, dipole

681

A. Mereghetti, R. Bruce, N. Fuster-Martínez, D. Mirarchi, S. Redaelli
CERN, Geneva, Switzerland

In the framework of the High-Luminosity Large Hadron Collider project (HL-LHC), the LHC collimation system needs important upgrades to cope with the foreseen brighter beams. New collimation hardware will be installed in two phases, the first one during the LHC second Long Shutdown (LS2), in 2019-20, followed by a second phase starting in 2024 (LS3). This paper reviews the collimation upgrade plans for LS2, focused on a first impedance reduction of the system, through the installation of collimators based on new materials, and the improvement of collimation cleaning, achieved by adding new collimators in the cold dispersion suppressor regions. The performance of the new system in terms of cleaning inefficiency for proton and lead ion beams is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB051

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paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB058

Collimation of Partially Stripped Ion Beams in the LHC

collimation, simulation, operation, hadron

700

A. Abramov, L.J. Nevay
JAI, Egham, Surrey, United Kingdom
R. Bruce, N. Fuster-Martínez, A.A. Gorzawski, M.W. Krasny, J. Molson, S. Redaelli, M. Schaumann
CERN, Meyrin, Switzerland

In the scope of the Physics Beyond Colliders studies, the Gamma Factory initiative proposes the use of partially stripped ions as a driver of a new type, high intensity photon source in CERN’s Large Hadron Collider (LHC). In 2018, the LHC accelerated and stored partially stripped 208-Pb-81+ ions for the first time. The collimation system efficiency recorded during this test was found to be prohibitively low. The worst losses were localised in the dispersion suppressor (DS) of the betatron-cleaning insertion. Analytic arguments and simulations show that the large losses are driven by the stripping of the remaining electron from the Pb nucleus by the primary collimators. The rising dispersion in the DS pushes the resulting off-rigidity, fully-stripped ions into the aperture of the superconducting magnets. In this study the measured loss maps are compared against results from simulations. Different mitigation strategies are outlined, including a dispersion suppressor (DS) collimator, crystal collimation or an orbit bump.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB058

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paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB059

Collimation of Heavy-Ion Beams in the HE-LHC

collimation, proton, hadron, simulation

704

A. Abramov, L.J. Nevay
JAI, Egham, Surrey, United Kingdom
R. Bruce, M.P. Crouch, N. Fuster-Martínez, A. Mereghetti, J. Molson, S. Redaelli
CERN, Meyrin, Switzerland

A design study for a future collider to be built in the LHC tunnel, the High-Energy Large Hadron Collider (HE-LHC), has been launched as part of the Future Circular Collider (FCC) study at CERN. It would provide proton collisions at a centre-of-mass energy of 27 TeV as well as collisions of heavy ions at the equivalent magnetic rigidity. HE-LHC is being designed under the stringent constraint of using the existing tunnel and therefore the resulting lattice and optics differ in layout and phase advance from the LHC. It is necessary to evaluate the performance of the collimation system for ion beams in HE-LHC in addition to proton beams. In the case of ion beams, the fragmentation and electromagnetic dissociation that relativistic heavy ions can undergo in collimators, as well as the unprecedented energy per nucleon of the HE-LHC, requires dedicated simulations. Results from a study of collimation efficiency for the nominal lead ion (Pb-82-208) beams performed with the SixTrack-FLUKA coupling framework are presented. These include loss maps with comparison against an estimated quench limit as well as detailed considerations of loss spikes in the superconducting aperture for critical sections of the machine such as the dispersion suppressors.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB059

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paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPRB072

eRHIC in Electron-Ion Operation

operation, electron, heavy-ion, hadron

738

W. Fischer, E.C. Aschenauer, E.N. Beebe, M. Blaskiewicz, K.A. Brown, D. Bruno, K.A. Drees, C.J. Gardner, H. Huang, T. Kanesue, C. Liu, M. Mapes, G.T. McIntyre, M.G. Minty, C. Montag, S.K. Nayak, M. Okamura, V. Ptitsyn, D. Raparia, J. Sandberg, K.S. Smith, P. Thieberger, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, A. Zaltsman, A. Zelenski
BNL, Upton, Long Island, New York, USA

Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
The design effort for the electron-ion collider eRHIC has concentrated on electron-proton collisions at the highest luminosities over the widest possible energy range. The present design also provides for electron-nucleon peak luminosities of up to 4.7·10³³ cm^-2s⁻¹ with strong hadron cooling, and up to 1.7·10³³ cm^-2s⁻¹ with stochastic cooling. Here we discuss the performance limitations and design choices for electron-ion collisions that are different from the electron-proton collisions. These include the ion bunch preparation in the injector chain, acceleration and intrabeam scattering in the hadron ring, path length adjustment and synchronization with the electron ring, stochastic cooling upgrades, machine protection upgrades, and operation with polarized electron beams colliding with either unpolarized ion beams or polarized He-3.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB072

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB098

An Increased Extraction Energy Booster Complex for the Jefferson Lab Electron Ion Collider

booster, electron, extraction, proton

797

E.A. Nissen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript.
The proposed Jefferson Lab Electron Ion Collider (JLE-IC) envisions an ion complex composed of an ion linac, two booster synchrotrons and a collider ring. The evolving design of the JLEIC booster required an increase in the extraction energy of the booster from 8 to 12.1 GeV kinetic energy, necessitating two machines instead of one. The decision was also made to switch to warm magnets, thus increasing the total radius of the 8 GeV booster. The second booster is now the same size as the collider rings. In this work we present the new designs for JLEIC’s Low Energy Booster (LEB) and High Energy Booster (HEB).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB098

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paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPTS065

Alternative Design of CEPC LINAC

linac, positron, electron, booster

1005

C. Meng, J. Gao, X.P. Li, G. Pei, J.R. Zhang
IHEP, Beijing, People’s Republic of China

Circular Electron-Positron Collider (CEPC) is a 100 km ring e⁺ e⁻ collider for a Higgs factory. The injector is composed of a Linac and a Booster. The baseline design of CEPC Linac is a normal conducting S-band linear accelerator with frequency in 2860 MHz, which can provide electron and positron beam at an energy up to 10 GeV and bunch charge up to 3 nC. To reduce the design difficulty of booster and booster magnet at low energy part, an alternative design of the Linac with C-band accelerating structure at high energy part is proposed and the energy is up to 20 GeV. The compre-hensive consideration of Linac design and damping ring design will be discussed. In this paper, the physics design of this scheme is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS065

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paper received ※ 16 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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MOPTS093

Ultra-High Vacuum Characterization of Molybdenum-Carbide Graphite for HL-LHC Collimators

vacuum, collimation, site, proton

1078

F. Carra, C. Accettura, A. Bertarelli, G. Bregliozzi, G. Cattenoz, S. Redaelli, M. Taborelli
CERN, Meyrin, Switzerland
M. Beghi
POLIMI, Milano, Italy
J. Guardia Valenzuela
Universidad de Zaragoza, Zaragoza, Spain

Funding: This work has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No. 730871. Research supported by the HL-LHC project
In view of the High-Luminosity upgrade of the Large Hadron Collider (LHC) collimation system, a family of novel molybdenum-carbide graphite (MoGr) composites was developed to meet the challenging requirements of HL-LHC beam-halo collimation, in particular the electrical conductivity and thermo-mechanical performances. The Ultra-High Vacuum (UHV) behaviour of this material was extensively characterized to assess its compatibility with the accelerator’s specifications. The results presented in this paper correlate the outgassing behaviour with the microscopic features of MoGr compared to other graphite-based materials. Residual gas analysis (RGA) was exploited to optimize post-production treatments.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS093

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paper received ※ 12 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPMP020

The Research on the Calibration of Direct-Current Current Transformers

power-supply, experiment, factory, data-acquisition

1280

C. Han, Y. Gao, X.L. Guo, P. Liu
IHEP, Beijing, People’s Republic of China

The measurement accuracy of direct current-current transformer (DCCT) is one of the key factors influencing the output of high-precision direct current power supply. In this paper, a calibration system designed by measuring resistance principle with a high accuracy direct current comparator (DCC) was presented for DCCT whose measurement accuracy is better than 10^-5. The system can achieve high-precision calibration of DCCT within the measurement range of 0-400 A, and the uncertainty of the system calibration is better than 1.1×10-6 in the whole range. The accuracy and linearity of DCCT are tested to verify the accuracy of the whole calibration system, thereby the current accuracy of the magnet power supply can be further improved.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP020

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPMP035

Design of the Vacuum System of the FCC-ee Electron-Positron Collider

vacuum, photon, dipole, quadrupole

1319

R. Kersevan, C. Garion
CERN, Geneva, Switzerland

The Future Circular Collider (FCC) Design Study includes the twin storage ring (FCC-ee) where electrons and positrons are stored and made to collide inside two detectors. The vacuum system of FCC-ee must be designed in order to deal with a lower-energy (45.6 GeV), high-current (1390 mA) Z-pole machine and at a later stage with a higher-energy (182.5 GeV) low-current (5.4 mA). The former machine is the most challenging one from the point of view of vacuum, since the photon-stimulated desorption (PSD) generated by the copious synchrotron radiation (SR) fans is quite large. While several concepts have been considered at the beginning, the design retained for the Conceptual Design Report (CDR) is one where the cross-section of the vacuum chamber (VC) in the arcs is a scaled-down version of the one implemented in the SUPERKEKB collider. Contrary to SUPERKEKB tough, the SR fans are absorbed by many short absorbers, with average spacing of 5.8 m. This allow a localization of the PSD gas load and to place lumped pumps in front of the SR absorbers, to maximize the pumping efficiency. The VC design is compatible with the design of the common-yoke dipoles and quadrupoles. The VC material is copper alloy. Optimization of the pressure profiles has been carried out by means of extensive coupled montecarlo simulations, for SR and molecular flow. For the higher energy versions of the machine, for which the SR spectra are characterized by critical energies well above the Compton edge, the localized absorbers facilitate also shielding the tunnel and any radiation-sensitive machine components from X-ray photon damage, by installing short high-Z material around the absorbers. The major features of the CDR relevant for vacuum will be highlighted in the paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP035

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPMP038

Summary of Modelling Studies on the Beam Induced Vacuum Effects in the FCC-hh

vacuum, electron, photon, synchrotron

1331

I. Bellafont, R. Kersevan, L. Mether
CERN, Geneva, Switzerland

Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305.
EuroCirCol is a conceptual design study of a Future Circular Collider (FCC-hh) which aims to expand the current energy and luminosity frontiers that the LHC has established. The vacuum chamber of this 50 TeV, 100 km collider, will have to cope with unprecedented levels of synchrotron radiation power for proton colliders, dealing simultaneously with a tighter magnet aperture. Since the high radiation power and photon flux will release large amounts of gas into the system, the difficulty to keep a low level of residual gas density increases considerably compared with the LHC. This article presents a study of the beam induced vacuum effects for the FCC-hh novel conditions, the different phenomena which, owing to the presence of the beam, have an impact on the vacuum level of the accelerator. To achieve this, a novel beam screen has been proposed, featuring specific mitigating measures aimed at dealing with the beam induced effects. It is concluded that thanks to the new beam screen design, the vacuum level in the FCC-hh shall be adequate, allowing to reach the molecular density requirement of better than 10¹⁵ H₂/m3 with baseline beam parameters within the first months of conditioning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP038

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paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB112

JLEIC: A High Luminosity Polarized Electron-Ion Collider at Jefferson Lab

electron, luminosity, proton, emittance

1916

Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The recent National Academies of Science Review concluded the science questions that could be answered by an electron-ion collider are significant to advancing our understanding of the atomic nuclei that make up all visible matter in the universe. To meet this science need, a high luminosity polarized electron-ion collider (JLEIC) was envisioned at Jefferson Lab, based on the existing CEBAF recirculated SRF electron linac. Over the past 16 years, Jefferson Lab has been actively engaged in the design study and accelerator R&D for JLEIC, a comprehensive Pre-Conceptual Design Report has been completed recently. The JLEIC baseline design has also been continuously optimized including extending the CM energy to 100 GeV. In this paper, we present a summary of the JLEIC baseline design and also briefly discuss the accelerator R&D.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB112

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paper received ※ 07 June 2019 paper accepted ※ 07 June 2019 issue date ※ 21 June 2019

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TUPTS099

Predicting the Performances of Coherent Electron Cooling with Plasma Cascade Amplifier

electron, plasma, kicker, space-charge

2150

G. Wang, V. Litvinenko, J. Ma
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Recently, we proposed a new type of instability, Plasma Cascade Instability (PCI), to be used as the amplification mechanism of a Coherent Electron Cooling (CeC) system, which we call Plasma Cascade Amplifier (PCA). In this work, we present our analytical estimate of the cooling force as expected from a PCA- based CeC system and compare it with the simulation results. As examples, we apply our analysis to a few possible CeC systems and investigate the evolution of the circulating ion beams in the presence of cooling.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS099

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEYPLM1

Status of Circular Electron-Positron Collider and Super Proton-Proton Collider

injection, luminosity, booster, cavity

2244

C.H. Yu, S. Bai, X. Cui, J. Gao, H. Geng, D.J. Gong, D. Ji, Y.D. Liu, C. Meng, Q. Qin, J.Y. Tang, D. Wang, N. Wang, Y. Wang, Y. Wei, J.Y. Zhai, Y. Zhang, H.J. Zheng, Y.S. Zhu
IHEP, Beijing, People’s Republic of China

Circular electron-positron collider (CEPC) is a dedi-cated project proposed by China to research the Higgs boson. The collider ring provides e⁺ e⁻ collision at two interaction points (IP). The luminosity for the Higgs mode at the beam energy of 120GeV is 3*10³⁴ cm^-2s^-1 at each IP while the synchrotron radiation (SR) power per beam is 30MW. Furthermore, CEPC is compatible with W and Z experiments, for which the beam energies are 80 GeV and 45.5 GeV respectively. The luminosity at the Z mode is higher than 1.7*10³⁵ cm^-2s^-1 per IP. Top-up operation is available during the data taking of high energy physics. Super Proton-Proton Collider (SPPC) is envisioned to be an extremely powerful machine, with centre mass energy of 75 TeV, a nominal luminosity of 1.0*10³⁵ cm^-2s^-1 per IP, and an integrated luminosity of 30 ab^-1 assuming 2 interaction points and ten years of running. The status of CEPC and SPPC will be introduced in detail in this paper.

Slides WEYPLM1 [11.814 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYPLM1

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEYYPLM3

First Results of the Compensation of the Beam-Beam Effect with DC Wires in the LHC

experiment, beam-beam-effects, operation, simulation

2262

G. Sterbini, D. Amorim, H. Bartosik, A. Bertarelli, R. Bruce, X. Buffat, F. Carra, L.R. Carver, G. Cattenoz, E. Effinger, S.D. Fartoukh, N. Fuster-Martínez, M. Gąsior, M. Gonzalez-Berges, A.A. Gorzawski, G.H. Hemelsoet, M. Hostettler, G. Iadarola, O.R. Jones, N. Karastathis, S. Kostoglou, I. Lamas Garcia, T.E. Levens, L.E. Medina Medrano, D. Mirarchi, J. Olexa, S. Papadopoulou, Y. Papaphilippou, D. Pellegrini, M. Pojer, L. Ponce, A. Poyet, S. Redaelli, A. Rossi, B. Salvachua, H. Schmickler, F. Schmidt, K. Skoufaris, M. Solfaroli, R. Tomás, G. Trad, D. Valuch, C. Xu, C. Zamantzas, P. Zisopoulos
CERN, Geneva, Switzerland
D. Amorim
Grenoble-INP Phelma, Grenoble, France
M. Fitterer, A. Valishev
Fermilab, Batavia, Illinois, USA
D. Kaltchev
TRIUMF, Vancouver, Canada
S. Kostoglou
National Technical University of Athens, Zografou, Greece
A.E. Levichev
BINP SB RAS, Novosibirsk, Russia
A. Poyet
Université Grenoble Alpes, Grenoble, France

The compensation of the long-range beam-beam interactions using DC wires is presently under study as an option for enhancing the machine performance in the frame of the High-Luminosity LHC project (HL-LHC). The original idea dates back more than 15 years. After the installation of four wire prototypes in the LHC in 2018, a successful experimental campaign was performed during the last months. The experimental setup and the main results are reported in this paper.

Slides WEYYPLM3 [6.371 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM3

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paper received ※ 06 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPGW121

Update on the JLEIC Electron Collider Ring Design

electron, optics, quadrupole, solenoid

2780

F. Lin, V.S. Morozov, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Cai, Y.M. Nosochkov
SLAC, Menlo Park, California, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515.
The design concept of electron collider ring in the Jefferson Lab Electron-Ion Collider (JLEIC) is based on a small beam size at the interaction point (IP) to boost the luminosity. With a chosen beta-star at the IP, electron beam size is determined by the equilibrium emittance obtained from the linear optics design. In this paper, we present an update on the lattice design of the electron ring considering not only preservation of low beam emittance, but also optimization of geometric arrangement. In particular, recent development of the lattice design has been focused on incorporating the vertical dogleg, which brings the electron beam to the ion beam plane for collisions, in the spin rotator design. The vertical dogleg is designed with no horizontal emittance growth, controlled vertical emittance and no first-order effect on the electron polarization.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW121

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paper received ※ 21 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPGW122

EXPERIMENTAL VERIFICATION OF TRANSPARENT SPIN MODE IN RHIC

polarization, controls, experiment, resonance

2783

V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
JLab, Newport News, Virginia, USA
P. Adams, H. Huang, F. Méot, V. Ptitsyn, W.B. Schmidke
BNL, Upton, Long Island, New York, USA
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
H. Huang
ODU, Norfolk, Virginia, USA
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

Funding: Supported in part by the U.S. DoE under Contract No. DE-AC05-06OR23177 and by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DoE.
High electron and ion polarizations are some of the key design requirements of a future Electron Ion Collider (EIC). The transparent spin mode, a concept inspired by the figure 8 ring design of JLEIC, is a novel technique for preservation and control of electron and ion spin polarizations in a collider or storage ring. It makes the ring lattice "invisible" to the spin and allows for polarization control by small quasi-static magnetic fields with practically no effect on the beam’s orbital characteristics. It offers unique opportunities for polarization maintenance and control in Jefferson Lab’s JLEIC and in BNL’s eRHIC. The transparent spin mode has been demonstrated in simulations and we now plan to test it experimentally. We present a design of an experiment using a polarized proton beam stored in one of the RHIC rings. In the experiment, one of the RHIC rings is configured in the transparent spin mode by aligning the axes of its two Siberian snakes. The experiment goals, procedures, hardware requirements and expected results are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW122

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW124

Spin Response Function for Spin Transparency Mode of RHIC

resonance, polarization, controls, lattice

2791

V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
JLab, Newport News, Virginia, USA
P. Adams, H. Huang, F. Méot, V. Ptitsyn, W.B. Schmidke
BNL, Upton, Long Island, New York, USA
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
H. Huang
ODU, Norfolk, Virginia, USA
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

Funding: Supported by the U.S. DoE under Contracts No. DE-AC05-06OR23177 and DE-AC02-98CH10886.
In the Spin Transparency (ST) mode of RHIC, the axes of its Siberian snakes are parallel. The spin tune in the ST mode is zero and the spin motion becomes degenerate: any spin direction repeats every particle turn. In contrast, the lattice of a conventional collider determines a unique stable periodic spin direction, so that the collider operates in the Preferred Spin (PS) mode. Contributions of perturbing magnetic fields to the spin resonance strengths in the PS mode are usually calculated using the spin response function. However, in that form, it is not applicable in the ST mode. This paper presents a response function formalism expanded for the ST mode of operation of conventional colliders with two identical Siberian snakes in the highly-relativistic limit. We present calculations of the spin response function for RHIC in the ST mode.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW124

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paper received ※ 01 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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WEPRB031

SRF Trip Caused by the Tuner in BEPCII

SRF, cavity, electron, operation

2880

J.P. Dai, Z.H. Mi, P. Sha, Y. Sun, Q.Y. Wang, L.G. Xiao
IHEP, Beijing, People’s Republic of China

Funding: Work support by Natural Science Foundation of China (11575216)
The stability and reliability of the Superconducting RF system (SRF) is generally a key issue in a large scale accelerator such as Beijing Electron Positron Collider II (BEPCII). In the past several years, SRF is one of the main factors limiting the availability of BEPCII, and many efforts have been made to fix the SCRF troubles. This paper focuses on the details of the SCRF trip caused by the tuner, which is one of the most persistent troubles and figured out till the summer of 2018.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB031

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paper received ※ 08 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPRB062

Spatially Resolved Dark Current in High Gradient Traveling Wave Structures

electron, linac, diagnostics, site

2956

J. Paszkiewicz, W. Wuensch
CERN, Meyrin, Switzerland
P. Burrows
JAI, Oxford, United Kingdom
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

High-gradient accelerating structures are known to produce field-emitted current from regions of high surface field, which are captured and accelerated by the fields within the structure. This current is routinely measured in structures under test in the CLIC high-gradient test stands using Faraday cups. This paper presents a novel technique to spatially resolve the longitudinal distribution of field emitted current by analysing downstream Faraday cup signals when the structure is fed with RF pulses much shorter than its filling time. Results from this method applied to X-band cavities operating at 100 MV/m are presented, and are compared to breakdown position distributions. A decay in emitted current as conditioning progressed in regions with a low breakdown rate and large jumps in regions with a large breakdown rate are observed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB062

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paper received ※ 29 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPRB069

Wakefield Suppression in a Manifold Damped and Detuned Structure for a 380 GeV CLIC Staged Design

wakefield, dipole, damping, accelerating-gradient

2980

N.Y. Joshi, R.M. Jones
UMAN, Manchester, United Kingdom

The first stage of the Compact Linear Collider (CLIC) project aims to collide electrons and positrons at a 380 GeV center of mass energy. In the baseline design the main linacs for this staged approach are required to achieve a gradient of 72 MeV/m, with the surface electromagnetic fields (EM) and the transverse long-range wakefields bound by beam dynamics constraints. The baseline design utilizes heavy damping in a traveling wave (TW) structure. Here we report on an alternate design, which adopts moderate damping along with strong detuning of the individual cell frequencies. In the context of this Damped and Detuned Structure (DDS) design, we study Gaussian and hyperbolic secant dipole distributions, together with interleaving of successive structures, to effect long-range transverse wakefield suppression. Both analytic and modal summation approaches, in the quasi-coupled approximation, produce consistent results. In the optimisation scheme we opt for a dipole frequency bandwidth of 17.7 % (2.92 GHz)

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB069

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paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPRB087

High-gradient SRF Cavity R&D at Cornell University

cavity, SRF, linear-collider, vacuum

3017

M. Ge, T. Gruber, J.J. Kaufman, P.N. Koufalis, G. Kulina, M. Liepe, J.T. Maniscalco
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Achieving high accelerating field is a critical R&D topic for superconducting RF cavities for future accelerators including the International Linear collider (ILC). The ILC requires an average accelerating field of 35MV/m with a Q₀ of at least 8.9·10⁹ at 2K. In this paper, we report the latest results from high-gradient research at Cornell, which focusses on 75C vacuum baking to improve maximum (quench) fields. We demonstrate that such low temperature bakes can significantly improve quench fields in certain cases by mitigating localized defects. We further report on high-pulsed power results of these cavities before and after baking.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB087

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paper received ※ 23 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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WEPRB093

Design of a Proof-of-principle Crabbing Cavity for the Jefferson Lab Electron-ion Collider

cavity, electron, HOM, luminosity

3027

H. Park, S.U. De Silva, J.R. Delayen, S.I. Sosa Guitron
ODU, Norfolk, Virginia, USA
J.R. Delayen, H. Park
JLab, Newport News, Virginia, USA

The Jefferson Lab design for an electron-ion collider (JLEIC) requires crabbing of the electron and ion beams in order to achieve the design luminosity. A number of options for the crabbing cavities have been explored, and the one which has been selected for the proof-of-principle is a 952 MHz, 2-cell rf-dipole (RFD) cavity. This paper summarizes the electromagnetic design of the cavity and its HOM characteristics.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB093

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paper received ※ 22 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

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WEPTS045

High-Performance Scheduling of Multi-Beam Multi-Bunch Simulations

simulation, wakefield, site, hadron

3208

S.V. Furuseth, X. Buffat
CERN, Geneva, Switzerland
S.V. Furuseth
EPFL, Lausanne, Switzerland

Coherent multi-bunch interactions through beam-beam forces or wake fields can cause severe impacts on the beams in circular colliders, if not well understood and countered for. COMBI is a parallel multiparticle tracking code developed to study such interactions. Its implementation greatly limits its efficiency when considering realistic configurations featuring effects with different computational requirements, such as the multi-bunch interaction through wake fields, beam-beam interactions, transverse feedback and lattice non-linearities. A new parallel scheduling method, pipelining the effects for each bunch, has greatly sped up the code. The new version of the code, COMBIp, is presented here.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS045

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paper received ※ 06 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPTS073

Beam-Beam Effect: Crab Dynamics Calculation in JLEIC

simulation, luminosity, electron, cavity

3293

H. Huang, F. Lin, V.S. Morozov, Y. Roblin, A.V. Sy, Y. Zhang
JLab, Newport News, Virgina, USA
I. Neththikumara, S. Sosa, B. Terzić
ODU, Norfolk, Virginia, USA

The electron and ion beams of a future Electron Ion Collider (EIC) must collide at an angle for detection, machine and engineering design reasons. To avoid associated luminosity reduction, a local crabbing scheme is used where each beam is crabbed before collision and de-crabbed after collision. The crab crossing scheme then provides a head-on collision for beams with a non-zero crossing angle. We develop a framework for accurate simulation of crabbing dynamics with beam-beam effects by combining symplectic particle tracking codes with a beam-beam model based on the Bassetti-Erskine analytic solution. We present simulation results using our implementation of such a framework where the beam dynamics around the ring is tracked using Elegant and the beam-beam kick is modeled in Python.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS073

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS081

An Analytic Approach to Emittance Growth from the Beam-Beam Effect with Applications to the LHeC

proton, emittance, electron, GUI

3307

E.A. Nissen
JLab, Newport News, Virginia, USA
D. Schulte
CERN, Meyrin, Switzerland

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript.
In colliders with asymmetric rigidity such as the proposed Large Hadron electron Collider, jitter in the weaker beam can cause emittance growth via coherent beam-beam interactions. The LHeC in this case would collide 7 TeV protons on 60 GeV electrons, which can be modeled using a weak-strong model. In this work we estimate the proton beam emittance growth by separating out the longitudinal angular kicks from an off-center bunch interaction and produce an analytic expression for the emittance growth per turn in systems like the LHeC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS081

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paper received ※ 01 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS082

Luminosity Studies of Asymmetric Crab Crossing in JLEIC

luminosity, ECR, electron, cavity

3311

E.A. Nissen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript.
The proposed Jefferson Lab Electron Ion Collider (JLE-IC) currently plans to use a crab crossing scheme to max-imize the available luminosity. It had been suggested that space and cost savings, as well as hadron beam quality improvements, could be realized by leaving the ion beam un-crabbed and increasing the crabbing angle of the elec-tron beam. This and variations in-between equal and totally one-sided crabbing are examined for both JLEIC and LHC parameters, with various changes in crabbing angle and frequency studied to maximize luminosity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS082

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paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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WEPTS104

Synchrotron Radiation Reflections in the CLIC Beam Delivery System

photon, detector, synchrotron, radiation

3363

D. Arominski, A. Latina, A. Sailer, D. Schulte
CERN, Meyrin, Switzerland

Synchrotron radiation (SR) reflection is an important issue for future linear colliders. High fluxes of the SR might impact the performance of the detector, through irradiation of the forward luminosity and beam quality calorimeters or of the innermost layers of the vertex detector. The photon reflections depend on the beam pipe apertures’ size, their shape, and materials used with various surface roughness. In this work, we present a study of SR including reflection for the 380 GeV and 3 TeV beam parameters and optics of the Compact Linear Collider’s Final Focus System. The simulations of the SR reflections using the Synrad+ software are presented and the impact on the detector is discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS104

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paper received ※ 29 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS108

Emittance Exchange in MICE

emittance, experiment, simulation, factory

3378

C. Brown
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
C.G. Whyte
USTRAT/SUPA, Glasgow, United Kingdom

Funding: STFC, NSF, DOE, INFN, CHIPP and more
The Muon Ionization Cooling Experiment, MICE, has demonstrated transverse emittance reduction through ionization cooling. Transverse ionization cooling can be used either to prepare a beam for acceleration in a neutrino factory or for the initial stages of beam cooling in a muon collider. Later stages of ionization cooling in the muon collider require the longitudinal emittance to be manipulated using emittance exchange and reverse emittance exchange, where emittance is exchanged from and to longitudinal phase space respectively. A wedge absorber within the MICE cooling channel has been used to experimentally demonstrate reverse emittance exchange in ionization cooling. Parameters for this test have been explored in simulation and applied to experimental configurations using a wedge absorber when collecting data in the MICE beam. This analysis of reverse emittance exchange is presented in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS108

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THAPLM3

2019 Nishikawa Tetsuji Prize Talk

electron, proton, operation, experiment

3439

V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

For his original work on electron lenses in synchrotron colliders, his outstanding contribution to the construction and operation of high-energy, high-luminosity hadron colliders and for his tireless leadership in the accelerator community.

Slides THAPLM3 [17.631 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THAPLM3

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paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPMP035

Tactile Collider : Accelerator Outreach to Visually Impaired Audiences

quadrupole, acceleration, detector, site

3518

R.B. Appleby, B. Jeffrey, B.S. Kyle, T.H. Pacey, H. Rafique, S.C. Tygier, R. Watson
UMAN, Manchester, United Kingdom
T. Boyd, A.L. Healy
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
C.S. Edmonds
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M.T. Hibberd
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom

Funding: STFC (UK)
The Large Hadron Collider (LHC) has attracted significant attention from the general public. The science of the LHC and Higgs Boson is primarily communicated to school children and the wider public using visual methods. As a result, people with visual impairment (VI) often have difficulty accessing scientific communications and may be culturally excluded from news of scientific progress. Tactile Collider is a multi-sensory experience that aims to communicate particle accelerator science in a way that is inclusive of audiences with VI. These experiences are delivered as a 2-hour event that has been touring the UK since 2017. In this article we present the methods and training that have been used in implementing Tactile Collider as a model for engaging children and adults with science. The event has been developed alongside experts that specialise in making learning accessible to people with VI.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP035

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paper received ※ 09 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW055

Improving High Precision Cam Mover’s Stiffness

FEM, alignment, interface, experiment

3713

J. Kemppinen
ETH, Zurich, Switzerland
H.M. Durand, A. Herty
CERN, Meyrin, Switzerland

Pre-alignment is a key challenge of the Compact Linear Collider (CLIC) study. The requirement for CLIC main beam quadrupole (MBQ) alignment is positioning to within 1 µm from target in 5 degrees of freedom (DOF) with ± 3 mm travel. After motion, the position should be kept passively while the system’s fundamental frequency is above 100 Hz. Cam movers are considered for the task. Traditionally they are used for the alignment of heavier magnets with lower accuracy and stiffness requirement. This paper presents a new CLIC prototype cam mover with design emphasis on the fundamental frequency. A finite element method (FEM) model predicts the mode shapes and eigenfrequencies of the system and can be used for further improving the design. Experimental modal analysis (EMA) of the prototype shows that the prototype’s fundamental frequency is at 44 Hz. It also validates the FEM model.
Juha. Kemppinen@cern.ch

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW055

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paper received ※ 01 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB073

Laboratory Measurements on Two ±12.5 kV Inductive Adders with ±0.02% Waveform Stability for CLIC Damping Ring Extraction Kickers

kicker, flattop, extraction, damping

3978

J. Holma, M.J. Barnes, A. Chmielinska
CERN, Geneva, Switzerland
M. Pont
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

The CLIC study is investigating the technical feasibil-ity of an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. Pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. The DR kicker systems must provide extremely stable field pulses to avoid beam emittance increase. Each DR extrac-tion kicker system consists of a set of striplines and two pulse modulators. Specifications for this system require that the modulator produce pulses of 900 ns flattop dura-tion, ±12.5 kV and 305 A, with ripple and droop of not more than ±0.02 % (±2.5 V) with respect to a reference waveform. Inductive adder topology has been chosen for the pulse modulators. Two full-scale, 20-layer, 12.5 kV prototype inductive adders have been designed, built and tested at CERN. This paper presents the measurements of the stability of these adders for two different waveforms: a flat-top waveform and a controlled decay waveform, the latter of which is required to generate flat-top total field for the CLIC DR extraction stripline kicker.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB073

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB096

Real-Time Beam Orbit Stabilisation to 200 Nanometres in Single-Pass Mode Using a High-Precision Dual-Phase Feedback System

feedback, extraction, electron, real-time

4049

D.R. Bett, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
JAI, Oxford, United Kingdom

A high-resolution, low-latency, stripline beam position monitor (BPM) system has been developed for use at particle accelerators and beamlines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system consists of fast analogue stripline BPM signal processors input to a custom FPGA-based digital feedback board which drives a pair of kickers local to the BPMs and nominally orthogonal in phase in closed-loop feedback mode, thus achieving both beam position and angle stabilisation. The feedback system was tested with the electron beam in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. Recent upgrades to the BPMs have increased the single-shot, real-time position resolution of the system to ~150 nm for a beam charge of 1.3 nC. We report the latest results which demonstrate the feedback system operating at this resolution limit and a beam stabilisation performance of 200 nm.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB096

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB113

Concept of Beam-Related Machine Protection for the Future Circular Collider

machine-protect, beam-losses, extraction, proton

4085

Y.C. Nie, R. Schmidt, J.A. Uythoven, C. Wiesner, D. Wollmann, M. Zerlauth
CERN, Meyrin, Switzerland

In the Future Circular Collider (FCC) study, a proton-proton circular collider (FCC-hh) is considered with a stored beam energy 20 times higher than that of the LHC. Any uncontrolled release of such energy could potentially result in severe damage to the accelerator components. Machine protection of the FCC-hh is hence very important and challenging. With a machine-protection strategy similar to the LHC, FCC would require up to three turns to dump the beam synchronously after a failure detection. Due to several possible ultrafast failures, which could lead to significant beam losses in a few turns, it is important to further reduce the reaction time of the machine protection system (MPS) for the FCC. Reducing the detection time of a failure by using faster beam monitors, e.g. diamond detectors, can reduce the time between a beam loss and the beam dump request. Communication delay of the interlock system to the beam dumping system can be reduced by using a more direct signal path. More than one beam-free abort gap will shorten the time required for the synchronization between the abort gap and the extraction kicker. Different failure scenarios are classified according to the speed of the failure onset and the subsequent increase of induced beam losses. The critical failure modes, their potential mitigations and impacts on the design of the MPS are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB113

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS041

Progress and TDR Plans of the Mechanical System of CEPC

detector, alignment, vacuum, dipole

4200

H. Wang, S. Bai, M.X. Li, Y.D. Liu, C. Meng, H. Qu, J.L. Wang, P. Zhang, N. Zhou
IHEP, Beijing, People’s Republic of China

The TDR of CEPC is aimed at the key science and technology problems and makes preparations for the real project. This paper will describe the progress of mechanical system including the regular supports and transport vehicle design, the mockup plan, the installation scenario of machine detector interface (MDI) and the movable collimator, as well as the TDR plans of mechanical system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS041

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paper received ※ 28 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPTS084

Magnet Design Optimization for Future Hadron Colliders

dipole, hadron, magnet-design, power-supply

4307

V.V. Kashikhin, V. Lombardo, G. Velev
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Fermilab in collaboration with other members of the US Magnet Development Program (MDP) is working on the development of accelerator magnets for future hadron colliders. A 4-layer, 15-T dipole with 60 mm aperture based on Nb₃Sn Low Temperature Superconductor (LTS) has been fabricated and tested. It is an important milestone of demonstrating readiness of the LTS magnet technology for the next generation of hadron colliders. At the same time, design studies aimed at boosting the magnet performance even further with the help of High Temperature Superconductors (HTS) are under way. This paper introduces a novel magnet technology - Conductor On Molded Barrel (COMB) optimized for the HTS materials and discusses possible steps towards its demonstration.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS084

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS087

Micro-aligned Solenoid for Magnetized Bunched-beam Electron Cooling of 100 GeV/u Ions

electron, solenoid, alignment, GUI

4314

P.M. McIntyre, J. Breitschopf, J. Gerity, J.N. Kellams
Texas A&M University, College Station, USA
J. Breitschopf, J. Gerity, J.N. Kellams, A. Sattarov
ATC, College Station, Texas, USA

Funding: This work is supported by grant DE-SC0018468 from the US Dept. of Energy.
Magnetized electron cooling of ion beams requires pre-cise alignment of the electron beam with the equilibrium trajectory of the ion bunch. For the parameters required for JLEIC, a solenoid with bore field ~1 T, length ~30 m, and rms alignment of ~μrad is required. Such precise alignment has never been accomplished in a 1 T solenoid. The design of a micro-aligned solenoid is presented. A gap-separated stack of thin steel washers is located inside the solenoid. The washer stack shields transverse magnet-ic fields from its interior by a factor of ~10. A 30-washer module of the structure was built and measured using ultra-sensitive capacitive probes using a coordinate meas-uring machine. The r.m.s. coplanarity of the washer gaps was measured to be <5 μm, consistent with the required micro-alignment.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS087

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paper received ※ 17 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS099

Fermilab Superconducting Nb₃Sn High Field Magnet R&D Program

dipole, operation, status, proton

4338

G. Velev, G. Ambrosio, E.Z. Barzi, V.V. Kashikhin, S. Krave, V. Lombardo, I. Novitski, S. Stoynev, D. Turrioni, X. Xu, A.V. Zlobin
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Magnets based on the modern Nb₃Sn conductor are the main candidates for future high-energy hadron colliders. Fermilab as part of the U.S. MDP executes an extensive R&D program on these high-field magnets. This program includes basic conductor and material R&D, quench per-formance studies, and building a meter-long high-field demonstrator. This paper summarizes the current status of the program including its recent results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS099

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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FRXXPLM1

High Field Superconducting Magnet Program for Accelerators in China

dipole, proton, superconducting-magnet, background

4359

Q.J. Xu
IHEP, Beijing, People’s Republic of China

High field superconducting magnets are crucial for high-energy particle accelerators. IHEP (institute for High Energy Physics, Beijing) is pursuing critical technologies R&D for future circular colliders like the Super Proton Proton Collider (SPPC). SPPC will need thousands of high field (12-20 T) superconducting magnets in around 20 years. A long term R&D roadmap of the advanced high field magnets has been made, aiming to push the technology frontier to the desired level, and a strong domestic collaboration is established, which brings together expertise of Chinese superconductivity community from fields of materials, physics, technology and engineering. The goal is to address prominent scientific and technological issues and challenges for high field applications of advanced superconducting materials. In the past year a model magnet with hybrid coils (NbTi and Nb₃Sn ) has been manufactured and tested, reaching a dipole field above 10 T in the two apertures. A full Nb₃Sn model has also been fabricated and tested with a coil made of iron based superconductor inserted in the center. An overview of the high field magnet program, R&D status and the future plans will be presented.

Slides FRXXPLM1 [10.978 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRXXPLM1

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paper received ※ 20 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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