Author: Ohmi, K.
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MOZA01 Simulated Beam-beam Limits for Circular Lepton and Hadron Colliders 27
  • K. Ohmi
    KEK, Ibaraki, Japan
  The beam-beam limit is one of the most important collider parameters. For lepton colliders the empirical tune shift limits are higher than for hadron colliders, which has been attributed to strong radiation damping. The beam-beam limit in hadron colliders, like the LHC, can be affected by noise. For future higher-energy colliders, like FCC-hh or SppC, the limit can be higher or lower, in the presence of still rather weak synchrotron radiation. For circular lepton colliders, like DAΦNE, SuperKEKB, FCC-ee or CepC, the effect of large Piwinski angle, and crab waist, as well as the dependence of the beam-beam limit on the number of interaction points are important questions. This presentation reviews the state of the art in weak-strong, quasi-strong-strong and strong-strong beam-beam simulations and reports the various dependencies of the simulated beam-beam limit on the aforementioned parameters.  
slides icon Slides MOZA01 [4.453 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOZA01  
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MOPOR019 Beta Function Measurement and Resonances Induced by Space Charge Force and Lattice Magnets 641
  • K. Ohmi, K.G. Sonnad
    KEK, Ibaraki, Japan
  J-PARC MR has been operated at tune (νxy)=(22.40,20.75). A new operating point around (21.4,21.4) has been proposed by simulation studies on space charge effect since 2013. Machine experiments at the operating point has been performed since 2014 and many encouraging results are being obtained. We discuss why new operating point is better than present one from view point of space charge effects.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR019  
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TUOBA01 Beam Commissioning of SuperKEKB 1019
  • Y. Funakoshi, T. Abe, T. Adachi, K. Akai, Y. Arimoto, K. Egawa, Y. Enomoto, J.W. Flanagan, H. Fukuma, K. Furukawa, N. Iida, H. Iinuma, H. Ikeda, T. Ishibashi, M. Iwasaki, T. Kageyama, H. Kaji, T. Kamitani, T. Kawamoto, S. Kazama, M. Kikuchi, T. Kobayashi, K. Kodama, H. Koiso, M. Masuzawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, S. Nakamura, T.T. Nakamura, H. Nakayama, T. Natsui, M. Nishiwaki, K. Ohmi, Y. Ohnishi, T. Oki, S. Sasaki, M. Satoh, Y. Seimiya, K. Shibata, M. Suetake, Y. Suetsugu, H. Sugimoto, M. Tanaka, M. Tawada, S. Terui, M. Tobiyama, S. Uehara, S. Uno, X. Wang, K. Watanabe, Y. Yano, S.I. Yoshimoto, R. Zhang, D. Zhou, X. Zhou, Z.G. Zong
    KEK, Ibaraki, Japan
  • D. El Khechen
    LAL, Orsay, France
  In this report, we describe the machine operation in the first 3 months of the Phase 1 commissioning of SuperKEKB. The beam commissioning is smoothly going on. Vacuum scrubbing, the optics corrections and others are described.  
slides icon Slides TUOBA01 [9.346 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOBA01  
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TUPOW006 Six-dimensional Phase-space Rotation and its Applications 1754
  • M. Kuriki, K. Negishi
    HU/AdSM, Higashi-Hiroshima, Japan
  • H. Hayano, R. Kato, K. Ohmi, M. Satoh, Y. Seimiya, J. Urakawa
    KEK, Ibaraki, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  Funding: This work is partly supported by Grant-in-Aid for Scientific Research by MEXT, Japan (KAKENHI) 25390126.
Recent progress on the accelerator science requires optimized phase space distributions of the beam for each applications. A classical approach to satisfy the requirements is minimizing the beam emittance with a bunch charge as much as possible. This classical approach is not efficient and not compatible to the beam dynamics nature. 6D phase-space rotation, e.g. z-x and x-y, gives a way to optimize the phase space distribution for various applications. In this article, we discus possible applications of the 6D phase space rotation. The x-y rotation generates the high aspect ratio beam for linear colliders directly without DR (Damping Ring). Combination of bunch clipping with a mechanical slit and x-z rotation can generate micro-bunch structure which is applicable for FEL enhancement and drive beam for dielectric acceleration. We present our theoretical and simulation study on these applications.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW006  
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WEPOY004 Integrated Green Function for Charged Particle moving along Bending Orbit 2997
  • K. Ohmi, S. Chen
    KEK, Ibaraki, Japan
  • H. Tanaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  Electro-magnetic field for moving charged particle is given by Liennard-Wiechert potential. The field contains high frequency component corresponding to synchrotron light, ω=3cγ3/(2ρ). The frequency is too high to study beam behavior generally. Green function integrated over beam distribution and/or over in a region σx/nx× σy/ny× σz/nz (nxyz ∼  10) is useful to study instability and emittance growth of the beam. The green function is regarded as the wake field for coherent synchrotron radiation in three dimension space.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY004  
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THPOR007 Optics Measurements and Corrections at the Early Commissioning of SuperKEKB 3782
  • Y. Ohnishi, Y. Funakoshi, H. Koiso, A. Morita, K. Ohmi, K. Oide, H. Sugimoto, D. Zhou
    KEK, Ibaraki, Japan
  • M.E. Biagini, M. Boscolo, S. Guiducci
    INFN/LNF, Frascati (Roma), Italy
  • N. Carmignani, S.M. Liuzzo
    ESRF, Grenoble, France
  We present experimental results of measurements and corrections of the optics at the early Phase-1 commissioning of SuperKEKB which is a positron-electron collider built to achieve the target luminosity of 8x1035 cm-2s-1. We have three stages; the Phase-1 is the commissioning of the machine without the final focus magnets and detector solenoid(no collision); the collision with the final focus system and the Belle II detector will be performed at the Phase-2 and Phase-3. The strategy for the luminosity upgrade is a novel "nano-beam'' scheme found elsewhere*. In order to achieve the target luminosity, the vertical emittance has to be reduced by corrections of machine error measured by orbit responses. The vertical emittance should be achieved to be less than 6 pm(0.2 % coupling) during the Phase-1 by fully utilizing correction tools of skew quadrupole-like coils wound on sextupole magnets and power supplies for each correction coil in quadrupole magnets. In addition to the linear optics, the optics for off-momentum particles is also studied to understand a dynamic aperture affects the Touschek lifetime.
* "SuperB Conceptual Design Report", INFN/AE-07/2, SLAV-R-856, LAL 07-15, (2007).
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR007  
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THPOR022 Design of Beam Optics for the FCC-ee Collider Ring 3821
  • K. Oide, K. Ohmi, D. Zhou
    KEK, Ibaraki, Japan
  • M. Aiba
    PSI, Villigen PSI, Switzerland
  • S. Aumon, M. Benedikt, H. Burkhardt, A. Doblhammer, B. Härer, B.J. Holzer, J.M. Jowett, M. Koratzinos, L.E. Medina Medrano, Y. Papaphilippou, J. Wenninger, F. Zimmermann
    CERN, Geneva, Switzerland
  • A.P. Blondel
    DPNC, Genève, Switzerland
  • A.V. Bogomyagkov, I. Koop, E.B. Levichev, P.A. Piminov, D.N. Shatilov, D.B. Shwartz, S.V. Sinyatkin
    BINP SB RAS, Novosibirsk, Russia
  • M. Boscolo
    INFN/LNF, Frascati (Roma), Italy
  • Y. Cai, M.K. Sullivan, U. Wienands
    SLAC, Menlo Park, California, USA
  A design of beam optics will be presented for the FCC-ee double-ring collider. The main characteristics are 45 to 175 GeV beam energy, 100 km circumference with two IPs/ring, 30 mrad crossing angle at the IP, crab-waist scheme with local chromaticity correction system, and "tapering" of the magnets along with the local beam energy. An asymmetric layout near the interaction region suppresses the critical energy of synchrotron radiation toward the detector at the IP less than 100 keV, while keeping the geometry as close as to the FCC-hh beam line. A sufficient transverse/longitudinal dynamic aperture is obtained to assure the lifetime with beamstrahlung and top-up injection. The synchrotron radiation in all magnets, the IP solenoid and its compensation, nonlinearity of the final quadrupoles are taken into account.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR022  
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