Author: Ohmori, C.
Paper Title Page
MOEPPB003 Status of the PRISM FFAG Design for the Next Generation Muon-to-Electron Conversion Experiment 79
 
  • J. Pasternak, A. Alekou, M. Aslaninejad, R. Chudzinski, L.J. Jenner, A. Kurup, Y. Shi, Y. Uchida
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • R. Appleby, H.L. Owen
    UMAN, Manchester, United Kingdom
  • R.J. Barlow
    University of Huddersfield, Huddersfield, United Kingdom
  • K.M. Hock, B.D. Muratori
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • D.J. Kelliher, S. Machida, C.R. Prior
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • Y. Kuno, A. Sato
    Osaka University, Osaka, Japan
  • J.-B. Lagrange, Y. Mori
    Kyoto University, Research Reactor Institute, Osaka, Japan
  • M. Lancaster
    UCL, London, United Kingdom
  • C. Ohmori
    KEK, Tokai, Ibaraki, Japan
  • T. Planche
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  • S.L. Smith
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • H. Witte
    BNL, Upton, Long Island, New York, USA
  • T. Yokoi
    JAI, Oxford, United Kingdom
 
  The PRISM Task Force continues to study high intensity and high quality muon beams needed for next generation lepton flavor violation experiments. In the PRISM case such beams have been proposed to be produced by sending a short proton pulse to a pion production target, capturing the pions and performing RF phase rotation on the resulting muon beam in an FFAG ring. This paper summarizes the current status of the PRISM design obtained by the Task Force. In particular various designs for the PRISM FFAG ring are discussed and their performance compared to the baseline one, the injection/extraction systems and matching to the solenoid channels upstream and downstream of the FFAG ring are presented. The feasibility of the construction of the PRISM system is discussed.  
 
TUPPC019 Beam Dynamics Simulations of J-PARC Main Ring for Damage Recovery from the Tohoku Earthquake in Japan and Upgrade Plan of Fast Extraction Operation 1200
 
  • Y. Sato, K. Hara, S. Igarashi, T. Koseki, K. Ohmi, C. Ohmori
    KEK, Ibaraki, Japan
  • H. Hotchi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  Magnets of Japan Proton Accelerator Research Complex (J-PARC) were shaken by the Tohoku Earthquake in Japan on March 11th, 2011. The alignment of J-PARC Main Ring (MR) received 20 mm displacement horizontally and 6 mm vertically. Beam dynamics simulations were performed to estimate the effect of the displacement on closed orbit distortions and beam loss in fast extraction (FX) operation of J-PARC MR. Based on the simulation results, we concluded that re-alignment of J-PARC MR was needed to achieve high-power beam. The re-alignment of MR was finished on October 28th, 2011. We also considered the effects of the earthquake on the upstream of MR to establish our upgrade plan, which was based on beam dynamics simulations optimizing collimator balance of injection beam transport (3-50BT) and MR, and RF patterns. J-PARC MR FX operation was resumed from December 2011.  
 
WEPPR007 Simulation Calculation of Longitudinal Beam Distribution in J-PARC MR 2949
 
  • K. Hara, T. Koseki, C. Ohmori
    KEK, Tokai, Ibaraki, Japan
  • Y. Sato
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
 
  The J-PARC accelerator complex consists of 3 accelerators, a linear accelerator, a rapid cycle synchrotron (RCS) and a Main Ring (MR) synchrotron. Simulation calculation of longitudinal beam distribution in J-PARC Main Ring has been performed. The effect that RF voltage pattern, space charge, and beam loading gave was examined.  
 
WEPPR008 Simulation of Controlled Longitudinal Emittance Blow-up in J-PARC RCS 2952
 
  • M. Yamamoto, M. Nomura, A. Schnase, T. Shimada, F. Tamura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
 
  In the J-PARC RCS, a high intensity beam is prepared for the MR. The longitudinal beam emittance at the RCS extraction should be optimized to avoid beam loss during and after MR injection. In order to match the longitudinal emittance shape between the RCS and the MR, it is desirable to enlarge the longitudinal emittance during the RCS acceleration. We have performed the particle tracking simulation for the controlled longitudinal emittance blow up in the RCS.  
 
THPPC005 Design of Magnetic Alloy Resonant System (MARS) Cavity for J-PARC MR 3278
 
  • C. Ohmori, K. Hara, K. Hasegawa, M. Toda, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  • M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
 
  The Magnetic Alloy Resonant System (MARS) cavity is a new type of Magnetic Alloy (MA) cavity using an external energy storage system. It is proposed as a back-up system of the present J-PARC high-Q MA cavity using cut cores. MARS consists of un-cut core loaded wideband MA cavities combined with an energy storage system using high-impedance, FT3L, cut cores. The main cavities are water-cooled and already established at J-PARC RCS. The energy storage system will be relatively high-Q (>100) to be stable under heavy beam loading. It also has a higher impedance than the main cavity and is air-cooled. The design of this cavity system will be presented.  
 
THPPC006 Status of the J-PARC Ring RF Systems 3281
 
  • M. Yoshii, E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda
    KEK, Tokai, Ibaraki, Japan
  • M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
 
  Due to the 11th march earthquakes, J-PARC was forced to stop operation. The restoration is following the schedule so that J-PARC is restarted in December. Before the earthquake, we had considerable success in the 400 kW equivalent proton beam in the RCS. Multi-harmonic RF feedforward was established, which contributes to the reduction of beam loss and stable acceleration in RCS. The MR synchrotron achieved stable 150 kW beam operation for the T2K experiment. This summer, we installed two new RF systems in MR. Eight RF systems in total allow a more stable beam acceleration and flexible bunch shape manipulation. Also, we prepare the RF feedforward to compensate beam loading in MR. To achieve a beam power in excess of 1 MW in MR, it is considered to double the MR repetition rate. We developed an annealing scheme for large magnetic alloy cores while inside a DC B-field that results in higher core impedance, and have succeeded in producing large FT3L cores in this summer. With such cores we can almost double the accelerating voltage without re-designing the existing RF sources. For the near future, we plan to replace the existing RF cavities with upgraded cavities using the FT3L cores.  
 
THPPP082 RF Feedforward System for Beam Loading Compensation in the J-PARC MR 3924
 
  • F. Tamura, M. Nomura, A. Schnase, T. Shimada, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • K. Hara, K. Hasegawa, C. Ohmori, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  • M. Toda
    KEK/JAEA, Ibaraki-Ken, Japan
 
  For acceleration of high intensity proton beams in the J-PARC MR, beam loading compensation is important. In the MA-loaded RF cavity in the MR, which has a Q-value in the order of 20, the wake voltage consists of the accelerating harmonic (h=9) and the neighbor harmonics (h=8, 10). We employ the RF feedforward method for the beam loading compensation, like in the J-PARC RCS, in which the impedance seen by the beam is greatly reduced by the feedforward. The full-digital feedforward system developed for the MR has a similar architecture to that of the RCS. The system compensates the beam loading of the important three harmonics (h=8, 9, 10). We present the structure of the RF feedforward system. Also, we report the preliminary results of the beam tests.