Keyword: positron
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MOPMF001 Bunch Schedules for the FCC-ee Pre-injector linac, injection, collider, booster 79
 
  • S. Ogur, K. Oide, Y. Papaphilippou, F. Zimmermann
    CERN, Geneva, Switzerland
  • D.N. Shatilov
    BINP SB RAS, Novosibirsk, Russia
  
  The latest design of the Future Circular electron-positron Collider (FCC-ee) foresees a luminosity per interaction point above 2.0·1036/cm2/s for operation at the Z pole. The filling from zero current occurs in collision to profit from the bunch lengthening due to beamstrahlung (so-called bootstrapping). At any time when new e- and e+ buckets or bunchlets are injected into the collider, they will collide instantly. For this reason, we may provide the charge in each injected bunch in a way to pre-compensate for anticipated beam loss, and to reach the target luminosity as soon as possible after the first injection. In this way, we optimise the injection schedules for Z-mode so as to reach the peak luminosity in less than 20 minutes by interleaved injection of the two species at some portion of full bucket charge. Filling from zero the injector should allow accumulating 1.7·1011 particles in one collider bucket within at least 10 injections, assuming a total transmission above 80%. In steady-state operation, the injector chain continually produces and accelerates lower bunch charges so as to maintain nearly constant bunch currents and constant peak luminosity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF001  
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MOPMF055 Update of the CLIC Positron Source target, linac, electron, simulation 236
 
  • Y. Han, L. Ma
    SDU, Shandong, People's Republic of China
  • C. Bayar
    Ankara University, Faculty of Sciences, Ankara, Turkey
  • S. Döbert, A. Latina, D. Schulte
    CERN, Geneva, Switzerland
  
  The baseline positron source of CLIC has been optimised for the 3 TeV c.o.m. energy. Now the first stage of the CLIC is proposed to be at 380 GeV. Recently, the positron transmission efficiency from the tungsten target to the damping rings injection has been improved by 2.5 times. This opened the possibility for an optimisation of the whole positron source, comprising the injector linacs, aimed at improving its performance and its overall power efficiency. In this paper the key parameters of the positron source, which include the current and the energy of the primary electron beam, the thickness of the crystal and amorphous tungsten targets, the distance between the two targets, the adiabatic matching device (AMD) and pre-injector linacs, are optimized to improve the overall power efficiency.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF055  
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MOPMF065 LHC- and FCC-Based Muon Colliders collider, emittance, target, factory 273
 
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  Funding: Work supported by the European Commission under the HORIZON 2020 project ARIES, grant agreement no. 730871.
In recent years, three schemes for producing low-emittance muon beams have been proposed: (1) e+e− annihilation above threshold using a positron storage ring with a thin target [M. Boscolo, P. Raimondi et al.], (2) laser/FEL-Compton back-scattering off high-energy proton beams circulating in the LHC or FCC-hh [L. Serafini et al.], (3) the Gamma factory concept, where partially stripped heavy ions collide with a laser pulse to directly generating muons [W. Krasny]. The Gamma factory would also generate copious amounts of positrons which could in turn be used as source for option (1). On the other hand the top-up booster of the FCC-ee design would be an outstanding e+ storage ring, at the right beam energy, around 45 GeV. After rapid acceleration the muons, produced in one of the three ways, could be collided in machines like the SPS, LHC or FCC-hh. Possible collider layouts are suggested. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF065  
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MOPMF073 Rejuvenation of 7-Gev SuperKEKB Injector Linac linac, electron, emittance, injection 300
 
  • K. Furukawa, M. Akemoto, D.A. Arakawa, Y. Arakida, H. Ego, A. Enomoto, Y. Enomoto, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, M. Kawamura, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, H. Nakajima, K. Nakao, T. Natsui, M. Nishida, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, I. Satake, M. Satoh, Y. Seimiya, A. Shirakawa, H. Sugimura, T. Suwada, T. Takenaka, M. Tanaka, N. Toge, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou
    KEK, Ibaraki, Japan
  
  KEK injector linac has delivered electrons and positrons for particle physics and photon science experiments for more than 30 years. It was upgraded for the SuperKEKB project, which aims at a 40-fold increase in luminosity over the previous project KEKB, in order to increase our understanding of flavor physics beyond the standard model of elementary particle physics. SuperKEKB energy-asymmetric electron-positron collider with its extremely high luminosity requires a high current, low emittance and low energy spread injection beam from the injector. The electron beam is generated by a new type of RF gun, that provides a much higher beam current to correspond to a large stored beam current and a short lifetime in the ring. The positron source is another major challenge that enhances the positron bunch intensity from 1 to 4 nC by increasing the positron capture efficiency, and the positron beam emittance is reduced from 2000 μm to 10 μm in the vertical plane by introducing a damping ring, followed by the bunch compressor and energy compressor. The summary of the rejuvenation is reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF073  
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MOPMF074 Beam Phase Space Jitter and Effective Emittance for SuperKEKB Injector Linac emittance, target, linac, electron 304
 
  • Y. Seimiya, N. Iida, T. Kamitani, M. Satoh
    KEK, Ibaraki, Japan
  
  In SuperKEKB linac, stable high charged low emittance beam is necessary. Transported beam to SuperKEKB Main Ring (MR) must be stable to the extent that the beam can be injected inside MR acceptance. SuperKEKB requirement must be satisfied for emittance including beam phase space jitter, called as effective emittance. Large amplitude beam position jitter has been measured at linac end. We evaluated that the effect of the beam position jitter on effective emittance and investigated the source of the beam phase space jitter.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF074  
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MOPMF076 Energy Spread Compensation in Arbitrary Format Multi-Bunch Acceleration With Standing Wave and Traveling Wave Accelerators beam-loading, acceleration, cavity, linac 307
 
  • M. Kuriki
    HU/AdSM, Higashi-Hiroshima, Japan
  
  In the E-driven ILC (International Linear Collider) positron source, the beam is generated and accelerated in a multi-bunch format with mini-trains. The macro-pulse contains 2 to 8 mini-trains with several train gaps, because the pulse format is a copy of a part of the bunch storage pattern in DR (Damping Ring). This pulse format causes a variation of the accelerator field in the pulse due to the transient beam loading and an intensity fluctuation of captured positron. In this article, we discuss the compensation of the energy spread of such beam in standing wave and traveling wave accelerators. For standing wave accelerator, it can be compensated by switching input RF at appropriate timings. For traveling wave accelerator, it can be compensated by amplitude modulation of the input RF.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF076  
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MOPMF077 A Design Study of the Electron-driven ILC Positron Source Including Beam Loading Effect beam-loading, cavity, acceleration, booster 311
 
  • H. Nagoshi, M. Kuriki
    HU/AdSM, Higashi-Hiroshima, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • K. Negishi
    Iwate University, Morioka, Iwate, Japan
  • T. Omori, M. Satoh, Y. Seimiya, J. Urakawa
    KEK, Ibaraki, Japan
  • Y. Sumitomo
    LEBRA, Funabashi, Japan
  • T. Takahashi
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
  
  The International Linear Collider (ILC) is a next-generation accelerator for high-energy physics to study the Higgs and top sector in the Standard Model, and new physics such as supersymmetry and dark matter. ILC positron source based on Electron-driven method has been proposed as a reliable technical backup. In this article, we report the design study of the positron source based on the off-the-shelf RF components. The positron is generated and accelerated in a multi-bunch format. To compensate the energy variation by the transient beam loading effect, we employ AM (Amplitude Modulation) technique and the results were 16.60 ± 0.14 MV (peak-to-peak) for L-band 2m cavity driven by 22.5 MW power and 25.76 ± 0.19 MV (peak-to-peak) for S-band 2m ac-celerator driven by 36 MW power with 0.78 A beam load-ing.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF077  
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MOPMF084 The Progress of CEPC Positron Source Design target, linac, electron, collider 319
 
  • C. Meng, 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 10 GeV linac and 120 GeV booster. The linac of CEPC is a normal conducting S-band linac with frequency in 2856.75 MHz and provide electron and positron beam at an energy up to 10 GeV and repetition frequency in 100 Hz. The positron source of CEPC is composed of target, flux concentrator, pre-accelerating section and beam separation system. The detailed design of each section of positron source will be presented and discussed, meanwhile the start-to-end dynamic simulation results will be presented also in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF084  
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MOPMF086 Proposal of an Experimental Test at DAΦNE for the Low Emittance Muon Beam Production From Positrons on Target target, emittance, experiment, optics 326
 
  • M. Boscolo, M. Antonelli, O.R. Blanco-García, S. Guiducci, A. Stella
    INFN/LNF, Frascati (Roma), Italy
  • F. Collamati
    INFN-Roma1, Rome, Italy
  • R. Li Voti
    Sapienza University of Rome, Rome, Italy
  • S.M. Liuzzo, P. Raimondi
    ESRF, Grenoble, France
  
  We present in this paper the proposal of an experimental test at DAΦNE of the positron-ring-plus-target scheme foreseen in the Low EMittance Muon Accelerator. This test would be a validation of the on-going studies for LEMMA and it would be synergic with other proposals at DAΦNE after the SIDDHARTA run. We discuss the beam dynamics studies for different targets inserted in a proper location through the ring, i.e. where the beam is focused and dispersion-free. Optimization of beam parameters, thickness and material of target and optics of the target insertion are shown as well. The development of the existent diagnostic needed to test the behavior of the circulating beam is described together with the turn-by-turn measurement systems of charge, lifetime and transverse size. Measurements on the temperature and thermo-mechanical stress on the target are also under study.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF086  
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MOPMF087 Muon Accumulator Ring Requirements for a Low Emittance Muon Collider from Positrons on Target target, emittance, collider, interaction-region 330
 
  • M. Boscolo, M. Antonelli, O.R. Blanco-García, S. Guiducci
    INFN/LNF, Frascati (Roma), Italy
  • F. Collamati
    INFN-Roma1, Rome, Italy
  • L. Keller
    SLAC, Menlo Park, California, USA
  • S.M. Liuzzo, P. Raimondi
    ESRF, Grenoble, France
  • D. Schulte
    CERN, Geneva, Switzerland
  
  Very low emittance muon beams can be produced by direct annihilation of about 45~GeV positrons on atomic electrons in a thin target. With such a muon beam source, a mu+mu- collider can be designed in the multi-TeV range at very high luminosities. In this scheme two muon accumulator rings are foreseen to recollect the muon bunches that will be injected in the collider. We present in this paper the first consideration of the muon accumulator rings. Realistic muon beam emittance and energy spread coming from the muon target are described. Constraints on the accumulator ring requirements are derived.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF087  
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MOPMK011 VEPP-5 Injection Complex: New Possibilities for BINP Electron-Positron Colliders electron, injection, collider, gun 371
 
  • Yu. Maltseva, A.V. Andrianov, K.V. Astrelina, V.V. Balakin, A.M. Batrakov, O.V. Belikov, D.E. Berkaev, M.F. Blinov, D. Bolkhovityanov, A. Butakov, E.V. Bykov, N.S. Dikansky, F.A. Emanov, A.R. Frolov, V.V. Gambaryan, K. Gorchakov, Ye.A. Gusev, S.E. Karnaev, G.V. Karpov, A.S. Kasaev, E. Kenzhbulatov, V.A. Kiselev, S. Kluschev, A.A. Kondakov, I. Koop, I.E. Korenev, N.Kh. Kot, V.R. Kozak, A.A. Krasnov, S.A. Krutikhin, I.V. Kuptsov, G.Y. Kurkin, N.N. Lebedev, A.E. Levichev, P.V. Logatchov, A.A. Murasev, V. Muslivets, D.A. Nikiforov, An.A. Novikov, A.V. Ottmar, A.V. Pavlenko, I.L. Pivovarov, V.V. Rashchenko, Yu. A. Rogovsky, S.L. Samoylov, N. Sazonov, A.V. Semenov, D.B. Shwartz, A.N. Skrinsky, A.A. Starostenko, D.A. Starostenko, A.G. Tribendis, A.S. Tsyganov, S.P. Vasichev, S.V. Vasiliev, V.D. Yudin, I.M. Zemlyansky, A.N. Zhuravlev
    BINP SB RAS, Novosibirsk, Russia
  • A.V. Andrianov, V.V. Balakin, F.A. Emanov, I. Koop, A.A. Krasnov, A.E. Levichev, D.A. Nikiforov, A.V. Pavlenko, Yu. A. Rogovsky, D.B. Shwartz, A.A. Starostenko
    NSU, Novosibirsk, Russia
  • A.I. Mickailov
    Budker INP & NSU, Novosibirsk, Russia
  • A.G. Tribendis
    NSTU, Novosibirsk, Russia
  
  VEPP-5 Injection Complex (IC) is designed to supply BINP RAS colliders with high energy electron and positron beams. Recently constructed K-500 beam transfer line connects IC to both VEPP-4M and VEPP-2000 colliders. IC two collider operation was successfully performed in 2016. Nowadays, research on improvement of IC productivity is carried out, in particular 10.94 MHz RF cavity instead of 700 MHz one was installed and a new electron gun installation is expected to be this summer. Moreover, longitudinal beam profile measurements in IC damping ring using a streak-camera were carried out. Operation experience of IC and results of longitudinal beam profile measurements are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK011  
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MOPML013 Progress on Preliminary Conceptual Study of HIEPA, a Super Tau-Charm Factory in China collider, factory, luminosity, electron 422
 
  • Q. Luo, D.R. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: Work supported by National Natural Science Foundation of China 11375178 and the Fundamental Research Funds for the Central Universities, Grant No WK2310000046.
As the most successful tau-charm factory of the world, BEPC II will celebrate its 10th birthday this year and will finish its historical mission in the next decade. Because of its very important role in high energy phys-ics study, BEPC II will certainly need a successor, a new tau-charm collider. This paper discusses the feasi-bility of a greenfield next generation tau-charm collid-er named HIEPA. The luminosity of this successor is about 5×1034 cm−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 parameters are shown. Several key technologies such as beam polarization and beam emittance diag-nostics are also discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML013  
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TUPAK009 Muon Profile Measurement After Acceleration With a Radio-Frequency Quadrupole Linac experiment, simulation, rfq, linac 977
 
  • M. Otani, Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, T. Yamazaki
    KEK, Tsukuba, Japan
  • S. Bae, H. Choi, S. Choi, B. Kim, H.S. Ko
    SNU, Seoul, Republic of Korea
  • K. Hasegawa, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-mura, Japan
  • T. Iijima, Y. Sue
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
  • H. Iinuma, Y. Nakazawa
    Ibaraki University, Ibaraki, Japan
  • K. Ishida
    RIKEN Nishina Center, Wako, Japan
  • R. Kitamura
    University of Tokyo, Tokyo, Japan
  • S. Li
    The University of Tokyo, Graduate School of Science, Tokyo, Japan
  • G.P. Razuvaev
    Budker INP & NSU, Novosibirsk, Russia
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • E. Won
    Korea University, Seoul, Republic of Korea
  
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP16H03987, and JP16J07784.
The E34 experiment aims to measure muon anomalous magnetic moment with a precision of 0.1ppm. The experiment utilizes low emittance muon beam with a muon linac to sweep out beam related uncertainties, which limit the g-2 precision in past experiments. A beam matching with precise beam measurements is required to avoid substantial emittance growth and satisfy the experimental requirement on the beam emittance of around 1.5 pi mm mrad. We conduct profile measurement of muon after acceleration with a radio-frequency quadrupole (RFQ) on December 2017 following a first muon acceleration experiment on October. In the experiment of profile measurement, epi-thermal negative muonium ions are generated by injecting surface muons to a thin metal foil. The muonium ions are accelerated to 5 keV. by an electro-static lens and accelerated to 90 keV by the RFQ. Then the muonium ions are transported to a profile detector consisting of a micro-channel plate and a ccd camera via a quadrupole pair and a bending magnet. In this poster, the experimental result and comparison to the simulation are reported. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK009  
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TUPMK016 Using Time Evolution of the Bunch Structure to Extract the Muon Momentum Distribution in the Fermilab Muon g-2 Experiment experiment, storage-ring, bunching, injection 1526
 
  • W. Wu, B. Quinn
    UMiss, University, Mississippi, USA
  • J.D. Crnkovic
    BNL, Upton, Long Island, New York, USA
  
  Beam dynamics plays an important role in achieving the unprecedented precision on measurement of the muon anomalous magnetic moment in the Fermilab Muon g-2 Experiment. It needs to find the muon momentum distribution in the storage ring in order to evaluate the electric field correction to muon anomalous precession frequency. We will show how to use time evolution of the beam bunch structure to extract the muon momentum distribution by applying a fast rotation analysis on the decay electron signals.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK016  
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WEYGBD3 The CERN Gamma Factory Initiative: An Ultra-High Intensity Gamma Source photon, factory, electron, neutron 1780
 
  • M.W. Krasny
    LPNHE, Paris, France
  • R. Alemany-Fernández, H. Bartosik, N. Biancacci, P. Czodrowski, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M.W. Krasny, M. Lamont, D. Manglunki, A.V. Petrenko, M. Schaumann, C. Yin Vallgren, F. Zimmermann
    CERN, Geneva, Switzerland
  • P.S. Antsifarov
    Institute of Spectroscopy, Russian Academy of Science, Troitsk, Moscow, Russia
  • A. Apyan
    ANSL, Yerevan, Armenia
  • E.G. Bessonov
    LPI, Moscow, Russia
  • J. Bieron, K. Dzierzega, W. Placzek, S. Pustelny
    Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
  • D. Budker
    Johannes Gutenberg University Mainz, Institut für Physik, Mainz, Germany
  • K. Cassou, I. Chaikovska, R. Chehab, K. Dupraz, A. Martens, Z.F. Zomer
    LAL, Orsay, France
  • F. Castelli
    Università degli Studi di Milano, Milano, Italy
  • C. Curatolo, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • K. Kroeger
    FSU Jena, Jena, Germany
  • V. Petrillo
    Universita' degli Studi di Milano & INFN, Milano, Italy
  • V.P. Shevelko
    LPI RAS, Moscow, Russia
  • T. Stöhlker
    HIJ, Jena, Germany
  • G. Weber
    IOQ, Jena, Germany
  • Y.K. Wu
    FEL/Duke University, Durham, North Carolina, USA
  • M.S. Zolotorev
    LBNL, Berkeley, California, USA
  
  This contribution discusses the possibility of broadening the present CERN research programme making use of a novel concept of light source. The proposed, Partially Stripped Ion beam driven, light source is the backbone of the Gamma Factory (GF) initiative. It could be realized at CERN by using the infrastructure of the already existing accelerators. It could push the intensity limits of the presently operating light-sources by up to 7 orders of magnitude, reaching fluxes of 1017 photons/s in the interesting gamma-ray energy domain between 1 MeV and 400 MeV. The GF light-source cannot be replaced, in this energy domain, by a FEL source as long as the multi TeV electron beams are not available. Its intensity is beyond the reach of the Inverse Compton Scattering sources. The unprecedented-intensity, energy-tuned gamma beams, together with the gamma-beams-driven secondary beams of polarized leptons, neutrinos, neutrons and radioactive ions are the basic research tools of the proposed Gamma Factory. A broad spectrum of new opportunities, in a vast domain of uncharted fundamental and applied physics territories, could be opened by the Gamma Factory research programme.  
slides icon Slides WEYGBD3 [7.531 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBD3  
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WEPAF015 Commissioning the Muon g-2 Experiment Electrostatic Quadrupole System quadrupole, storage-ring, experiment, resonance 1848
 
  • J.D. Crnkovic, V. Tishchenko
    BNL, Upton, Long Island, New York, USA
  • K.E. Badgley, H. Nguyen, E. Ramberg
    Fermilab, Batavia, Illinois, USA
  • E. Barlas Yucel, M. Yucel
    Istanbul Technical University, Maslak, Istanbul, Turkey
  • J.M. Grange
    ANL, Argonne, Illinois, USA
  • A.T. Herrod
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • A.T. Herrod
    The University of Liverpool, Liverpool, United Kingdom
  • J.L. Holzbauer, W. Wu
    UMiss, University, Mississippi, USA
  • H.D. Sanders
    APP, Freeville, New York, USA
  • H.D. Sanders
    Sanders Pulsed Power LLC, Batavia, Illinois, USA
  • N.H. Tran
    BUphy, Boston, Massachusetts, USA
  
  The Fermilab Muon g-2 experiment aims to measure the muon anomaly with a precision of 140 parts-per-billion (ppb) - a fourfold improvement over the 540 ppb precision obtained by the BNL Muon g-2 experiment. These high precision experiments both require a very uniform muon storage ring magnetic field that precludes the use of vertical-focusing magnetic quadrupoles. The Fermilab Electrostatic Quadrupole System (EQS) is the refurbished and upgraded BNL EQS, where this overview describes the Fermilab EQS and its recent operations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF015  
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WEPAF042 Measurement of Beam yz Crabbing Tilt Due to Wake Fields Using Streak Camera at CESR wakefield, storage-ring, coupling, cavity 1905
 
  • S. Wang, D. L. Rubin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: This research was supported by NSF PHYS-1068662, PHYS-1416318 and DMR-1332208.
Transverse vertical wake fields can increase the vertical emittance and distort the phase space of a bunch in a storage ring. Recently, we observed charge-dependent vertical beam size growth with a single scraper inserted through the top of the storage ring vacuum chamber. This apparent growth was due in large part to the yz coupling (vertical crabbing) induced by the wake field from the asymmetric scraper configuration. Here, we report a direct measurement of a small beam yz crabbing tilt using a streak camera. The recorded images (projected beam profiles in yz plane) are analyzed with three different methods, which yield consistent beam yz tilts. We found the directly-measured current-dependent beam tilts by the streak camera are consistent with the beam tilts calculated from a wake field model. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF042  
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WEPAK017 Low-level RF System for the SuperKEKB Injector LINAC linac, injection, booster, controls 2131
 
  • T. Matsumoto, M. Akemoto, D.A. Arakawa, H. Katagiri, T. Miura, F. Qiu, Y. Yano
    KEK, Ibaraki, Japan
  • M. Akemoto, T. Miura, F. Qiu
    Sokendai, Ibaraki, Japan
  
  The low-level RF (LLRF) system of the KEK injector linac has been upgraded for the SuperKEKB. As a major change, a low-emittance and high-current RF gun was installed to satisfy 40-times higher luminosity at the SuperKEKB. In order to balance the stable RF gun operation and the electron/positron beam acceleration, the phase shifter is developed and the configuration of main drive system in the LLRF system is modified. The present status and future plan of the LLRF system upgraded for the SuperKEKB will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK017  
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WEPAL066 Determination of RF Resonator Axis Inclination to Beam Axis in Electron-Positron Storage Ring experiment, resonance, kicker, electron 2330
 
  • Leshenok D. Leshenok
    NSU, Novosibirsk, Russia
  • S.A. Nikitin
    BINP SB RAS, Novosibirsk, Russia
  
  We proposed and tested the method that allows obtaining of an upper limit for an angle of the RF resonator axis inclination relative to a beam axis. Such disturbance gives an additional contribution to separation of electron and positron orbits due to action of the transverse component of the electric field. In the horizontal plane, this effect can lead to increase of the difference between electrons and positrons spin precession frequencies in a storage mono-ring collider. This effect can play a great role in FCC. At the angular disturbance of axis in the certain VEPP-4M RF resonators ~10-3 rad, the difference between the spin frequencies is about 10-8. Our method is based on resonant excitation of betatron oscillations using phase modulation of the master oscillator of the RF system. The maximal amplitude of the enforced oscillations is measured by the counting rate of the VEPP-4M Touschek polarimeter scintillation counters. Comparison of the obtained results with the data of the special calibration experiment allows estimating the value of the inclination angle. In this calibrated experiment the betatron oscillations excite using the VEPP-4M kicker.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL066  
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WEPML057 First Commissioning of Vacuum System of Positron Damping Ring for SuperKEKB photon, vacuum, MMI, operation 2826
 
  • K. Shibata, H. Hisamatsu, T. Ishibashi, K. Kanazawa, M. Shirai, Y. Suetsugu, S. Terui
    KEK, Ibaraki, Japan
  
  To satisfy the requirements of high beam quality for positron injection into the SuperKEKB main ring, a new damping ring (DR) is constructed in an upgraded injector system. The DR is a racetrack-shaped storage ring with a circumference of 135.5 m, in which the 1.1 GeV positron beam is stored for 40 ms to damp the emittance. The maximum stored beam current is 70.8 mA. Required beam lifetime due to residual gas scattering is longer than 1000 s and the average pressure should be lower than 10-5 Pa. Non-evaporable getter (NEG) pumps are mainly used, and the average effective pumping speed for CO is expected to be 0.013 m3s−1m-1 immediately after NEG activation. The beam pipes are made of aluminum alloy, and have antechambers to deal with synchrotron radiation (critical energy 0.8-0.9 keV, total power 7.2 kW) in arc sections, which are effective in reducing the electron cloud and the impedance of the beam pipes. As additional countermeasures against the electron cloud effect, TiN coating and grooved surfacing are also adopted. The commissioning of the DR will commence at the beginning of 2018. The status of the vacuum system of the DR during the first commissioning will be reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML057  
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WEPML058 Observation of Pressure Bursts in the SuperKEKB Positron Ring MMI, luminosity, electron, operation 2830
 
  • S. Terui, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, Y. Suetsugu
    KEK, Ibaraki, Japan
  
  The SuperKEKB is an electron-positron collider with asymmetric energies in KEK aiming an extremely high luminosity of 8x1035 cm-2 s-1 using a nano-beam scheme. In the Phase 1 commissioning from February to June, 2016, the vacuum system of the main ring worked well as a whole at stored beam currents of approximately 1 A. However, the localized pressure bursts accompanied by beam losses were observed in the positron ring. The beam loss monitors triggered beam aborts, and the phenomena has became an obstacle to the beam commissioning. These pressure bursts were frequently observed from the early stage of the commissioning. Most of the pressure bursts occurred near or inside of aluminum-alloy beam pipes in dipole magnets, which have grooved surface at the top and bottom sides. The various observations indicates that the most probable cause of this phenomenon was the collision between the dusts dropped from the grooves and the circulating positron beam. We report the properties and the probable causes of the pressure bursts, and the possible mitigation methods. Some results of the countermeasures taken prior to the ongoing Phase-2 commissioning will be also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML058  
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WEPML071 Superconducting 16-Pole Wiggler for Beijing Electron-Positron Collider II wiggler, vacuum, impedance, collider 2853
 
  • M.X. Li, X.J. Bian, F.S. Chen, W. Chen, X.J. Sun, H. Wang, J.L. Wang, N. Wang, M.F. Xu, X.C. Yang
    IHEP, Beijing, People's Republic of China
  
  A superconducting 16-pole 2.6T wiggler with period 170mm of The High-Energy Photon Source and the Test Facility Project (HEPS-TF) designed and fabricating in the Institute of High Energy Physics (IHEP) in China is described. This wiggler will be installed in Beijing Electron-Positron Collider II (BEPCII). The main parameters and structure of the wiggler are presented. Besides, some vertical testing results are involved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML071  
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WEPML076 The Magnetic Measurement of Enhancer-Dipole Magnet for CEPC collider, collimation, electron, dipole 2866
 
  • Z. Zhang, H. Wang
    IHEP, Beijing, People's Republic of China
  
  The CEPC (Circular Electron Positron Collider) project is in the pre-research stage. When the beam energy of booster is 120 GeV, the magnetic field of deflection magnet is 640 Gs. In order to save funds for scientific research, we also consider the injection energy of 6 GeV, the magnetic field of deflection magnet is 32 Gs. At the different current, the magnetic field value of the enhancer-dipole magnet can reach the beam energy range of 6 Gev-120 GeV. In such a requirements of magnetic field, the stability of the magnetic field value, repeatability, magnet magnetism, has become an important data for the design parameters of enhancer-dipole magnet. The magnet is measured with the Hall-Probe measurement facility by IHEP. In this paper, first written the procedure of motor control and collection by Labview software, then hen the excitation curve（repeat the measurement six times）, transverse field distribution（repeat the measurement three times）, and integral field distribution are measured. Based on the results of the analysis of large amounts of data, the stability and repeatability of the enhance-dipole magnet in different magnetic fields has summarized and analyzed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML076  
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THPAF025 Progress in Measurement and Modeling of Electron Cloud Effects at CesrTA electron, dipole, simulation, emittance 3007
 
  • S. Poprocki, S.W. Buechele, J.A. Crittenden, D. L. Rubin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
The synchrotron-radiation-induced buildup of low-energy electron densities in positron and proton storage rings limits performance by causing betatron tune shifts and incoherent emittance growth. The Cornell Electron Storage Ring (CESR) Test Accelerator project includes extensive measurement and modeling programs to quantify such effects and apply the knowledge gained to the design of future accelerator projects. We report on improved measurements of betatron tune shifts along a train of positron bunches, now accurate in both horizontal and vertical planes. Improved electron cloud buildup modeling uses detailed information on photoelectron production properties obtained from recently developed simulations and successfully describes the measurements after determining ring-wide secondary-yield properties of the vacuum chamber by fitting the model to data with a multi-objective optimizer. Cloud splitting in dipole magnetic fields is seen to be the source of horizontal tune shifts decreasing at higher bunch populations. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF025  
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THPAF089 Mode Coupling Theory in Collisions With a Large Crossing Angle coupling, dipole, synchrotron, collider 3197
 
  • N. Kuroo
    UTTAC, Tsukuba, Ibaraki, Japan
  • K. Hirosawa, K. Ohmi, D. Zhou
    KEK, Ibaraki, Japan
  • K. Oide, F. Zimmermann
    CERN, Geneva, Switzerland
  
  We discuss a novel coherent beam-beam instability in collisions with a large crossing angle. The instability appears in the correlated head-tail motion of the two colliding beams. Cross wake force is introduced to represent the head-tail correlation between colliding beams. The cross wake force is localized at the collision point. Mode coupling theory based on the cross wake force is developed. Collision scheme with a large crossing angle is being very popular in design of electron positron collider. In SuperKEKB project, a collision with a large crossing angle is performed to boost the luminosity ~ 1036 cm-2s−1. Future circular collider, FCC is also designed with a large crossing angle. Strong-strong simulations have shown a strong coherent head-tail instability, which can limit the performance of proposed future colliders. The mode coupling theory using the cross wake force explains the instability. The instability may affect all colliders designs based on the crab waist scheme.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF089  
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THPAK016 Measurement and Analysis of Synchrotron Tune Variation with Beam Current in BEPCII synchrotron, cavity, electron, impedance 3237
 
  • N. Wang, Z. Duan, G. Xu, H.S. Xu, C.H. Yu, Y. Zhang
    IHEP, Beijing, People's Republic of China
  
  Coherent synchrotron frequency shift is observed during machine studies in BEPCII (Beijing Electron Positron Collider Upgrade). The results show that the synchrotron frequency varies parabolically with the increase of the beam current. This phenomenon is supposed to be induced by the interaction of the beam with the fundamental mode of the accelerating cavity. In order to explain this phenomenon, a simple physical model is developed from the couple bunch instability theory. The analytical estimations based on the physical model show good agreement with the measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK016  
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THPAK020 Optics Model and Measurements of the DAΦNE Transfer Lines injection, operation, optics, dipole 3249
 
  • O.R. Blanco-García, A. De Santis, G. Di Pirro, C. Milardi, D. Pellegrini, A. Stecchi, A. Stella
    INFN/LNF, Frascati (Roma), Italy
  
  The different components of the DAΦNE accelerator complex: LINAC, Damping Ring and two colliding rings are connected by a composite system of Transfer Lines which, thanks to adaptive configurations, are able to transport electron and positron beams at 510~MeV. Recently, thanks to the introduction of new diagnostics tools, the optics model of the DAΦNE Transfer Lines has been improved and succesfully used to make the collider operations more efficient. The measurements done by using the new tools and their impact on the optics model optimization process are presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK020  
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THPAK023 Proposal for Using DAΦNE as Pulse Stretcher for the Linac Positron Beam extraction, septum, linac, pulse-stretcher 3258
 
  • S. Guiducci, D. Alesini, M.E. Biagini, S. Bilanishvili, O.R. Blanco-García, M. Boscolo, B. Buonomo, S. Cantarella, D.G.C. Di Giulio, L.G. Foggetta, A. Gallo, A. Ghigo, L. Kankadze, C. Milardi, R. Ricci, U. Rotundo, L. Sabbatini, M. Serio, A. Stella
    INFN/LNF, Frascati (Roma), Italy
  • P. Valente
    INFN-Roma, Roma, Italy
  
  The PADME experiment* proposes a search for the dark photon (A') in the e+e− -> gamma A' process in a positron-on-target experiment, exploiting the positron beam of the DAΦNE linac at the Frascati National Laboratory. The linac could provide a number of positrons as high as 109/pulse in a 200 ns pulse but the number of positrons for PADME is limited below 105/pulse in order to keep the pile-up probability in the calorimeter low enough. The PADME experiment is indeed limited by the low duty factor (10e-5=200ns/20ms). An alternative proposal to use the DAΦNE positron ring as a linac pulse stretcher, by injecting each pulse into the ring and extracting it by a slow resonant extraction using the m/3 resonance, is described in this paper. This allows to distribute the positrons of a linac pulse in a much longer pulse (0.2 - 0.5 ms) increasing the duty factor up to ~ 2%. The required modifications of the DAΦNE positron transfer line and main ring are presented. A dedicate lattice for the ring has been designed and tracking of the positrons in the ring has been performed to optimize extraction parameters and give a preliminary estimate of the extracted beam characteristics.
* M. Raggi et al., EPJ Web Conf. 96 (2015) 01025 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK023  
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THPAK139 Lost Muon Studies for the Muon g-2 Experiment at Fermilab experiment, storage-ring, background, resonance 3573
 
  • S. Ganguly, K. T. Pitts
    University of Illinois at Urbana-Champaign, Urbana, USA
  • J.D. Crnkovic
    BNL, Upton, Long Island, New York, USA
  • C. C. Polly
    Fermilab, Batavia, Illinois, USA
  
  The Fermilab Muon g-2 experiment aims to measure the muon anomalous magnetic moment aμ with an unprecedented precision of 140 parts per billion (ppb), a four-fold improvement over the 540~ppb precision obtained by the BNL Muon g-2 Experiment. This study presents preliminary work on estimating the muon losses by using double coincidences in the calorimeters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK139  
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THPAL011 Fast Ramped Dipole and DC Quadrupoles Design for the Beam Test Facility Upgrade dipole, quadrupole, linac, electron 3638
 
  • L. Sabbatini, E. Di Pasquale, L. Pellegrino, C. Sanelli, G. Sensolini
    INFN/LNF, Frascati (Roma), Italy
  • P. Valente
    INFN-Roma, Roma, Italy
  • A. Vannozzi
    Sapienza University of Rome, Rome, Italy
  
  The Beam Test Facility (BTF) is part of the DAΦNE accelerators system of INFN Frascati National Laboratory. It is a transfer-line optimized for electrons and positrons extracted from the DAΦNE LINAC. An upgrade of the line is planned in order to reach a beam energy of 920 MeV (with respect to the present 750 MeV), adding a new branch to the present transfer line. The design of the magnets for this new layout has been completely performed at INFN, including electromagnetic, mechanical, thermal and hydraulic aspects. This effort lead to a complete set of detailed CAD drawings that can be used by Industrial partners to build the magnets. The manufacturing processes have been studied in detail: the goal is to boost the manufacturing of prototypes and small series from Small and Medium Enterprises. Magnetic measurements will be performed at our Institute. In this report we describe two types of magnets for this project. The first magnet is a C-shape fast ramped dipole, designed for a beam deflection of 15 degrees; the rise time is 100ms, the gap is 25mm with a magnetic field of 1.11 T. The second is a family of seven quadrupoles with a gradient of 20 T/m and a bore of 45mm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL011  
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FRXGBD4 Observation of Saw-Tooth Effect Orbit in the VEPP-4 M Collider electron, experiment, collider, storage-ring 5026
 
  • Leshenok D. Leshenok, E.A. Bekhtenev
    NSU, Novosibirsk, Russia
  • E.A. Bekhtenev, G.V. Karpov, S.A. Nikitin, O.A. Plotnikova
    BINP SB RAS, Novosibirsk, Russia
  
  We study the relative position of the electron and posi-tron closed orbits in the VEPP-4M single storage ring collider in experiments on orbit precision monitoring. A difference in the orbits can affect the accuracy of several fundamental experiments, e.g. precise comparison of the electron and positron spin frequencies (the CPT invari-ance test) [1]. In this case, the spin precession frequencies of particles should be compared within at least 5·10-9. The distinction of frequencies depends on the features of the radial orbits. Ideally, the difference in the electron and positron orbits is set only by distributed radiation losses of particle energy. The corresponding contribution to the total orbit distortions is called the Saw-Tooth effect orbit. Another example of possible precision experiment at VEPP-4M is search for the light speed anisotropy (LSA). In this case, it is necessary to ensure a stability of the difference in the radial orbits of electrons and positrons at a level of 1μm.  
slides icon Slides FRXGBD4 [1.602 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-FRXGBD4  
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FRXGBE2 Muon Beam Dynamics and Spin Dynamics in the g-2 Storage Ring quadrupole, storage-ring, injection, experiment 5029
 
  • D. L. Rubin, A.T. Chapelain
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • S. Charity, J. Price
    The University of Liverpool, Liverpool, United Kingdom
  • J.D. Crnkovic, W. Morse, V. Tishchenko
    BNL, Upton, Long Island, New York, USA
  • F.E. Gray
    Regis University, Denver, USA
  • J. E. Mott
    BUphy, Boston, Massachusetts, USA
  • W. Wu
    UMiss, University, Mississippi, USA
  
  Funding: This work was supported in part by the U.S. Department of Energy DOE HEP DE-SC0008037
The goal of the new g-2 experiment at fermilab is a measurement of the anomalous magnetic moment of the muon, with uncertainty of less than 140 ppb. The experimental method is to store a beam of polarized muons in a storage ring with pure vertical dipole field and electrostatic focusing, and to measure the precession frequency. Control of the systematics depends on unprecedented knowledge of the details of the phase space of the muon distribution. That knowledge is derived from direct measurements with scintillating fiber detectors that are inserted into the muon beam for diagnostic measurements, traceback straw tube tracking chambers, as well as the calorimeters that measure energy, time and position of the decay positrons. The interpretation of the measurements depends on a detailed model of the storage ring guide field. This invited talk presents results of studies of the distribution from the commissioning run of the experiment. 		 
slides icon Slides FRXGBE2 [12.809 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-FRXGBE2  
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