A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z  

Yamamoto, K.

Paper Title Page
MOPC133 Radiation Level in the J-PARC Rapid Cycling Synchrotron after First Study 382
 
  • K. Yamamoto, N. Hayashi, S. Hiroki, R. Saeki
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • K. Satoh, M. Tejima
    KEK, Ibaraki
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken
  
  The 3GeV RCS (Rapid-Cycling Synchrotron) in J-PARC has been commissioned in October of 2007. The most important issue in the beam study is to reduce unnecessary beam loss and to keep the beam line clean for the sake of maintenance and upgrade of the machines. In order to achieve this purpose, we observed the beam loss monitors located around the RCS beam line and observed them for beam commissioning. We also investigated the residual dose of accelerator components during an interval of beam study. From these results, we found that beam loss points were the injection junction point, the branch of H0 dump and extraction line, transverse collimators, and dispersion maximum points in the arcs. Especially, the entrance of the primary collimator chamber and the current transformer of the H0 dump line were the most radio-activated points in the RCS. To make the best use of these results for beam commissioning, we managed to minimize the beam losses and succeeded in suppressing the residual dose to a level low enough to allows us to work close to those components.  
TUPC092 An Application for Beam Profile Reconstruction with Multi-wire Profile Monitors at J-PARC RCS 1272
 
  • H. Sako, S. Hiroki, K. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • H. Ikeda
    Visual Information Center, Inc., Ibaraki-ken
  • H. Takahashi
    JAEA, Ibaraki-ken
  
  J-PARC RCS is commissioned since October 2007. In the early stage of RCS commissioning, Multi-Wire Profile Monitors (MWPM's) are most important beam monitors to measure positions and profiles of beam orbit in the injection line from LINAC. A MWPM consists of either a horizontal or a vertical wire plane. Each wire plane consists of several wires which has a tilt angle, and a wire scatters H- or proton beams and induced current in the wire is detected. A wire plane moves at a small step in the perpendicular direction to the wires and scans a beam profile. A complex analysis procedure and geometrical description is developed to reconstruct a beam profile from a MWPM. Beam profiles have been measured at MWPM's in the injection line and the H0 beam dump line.  
TUPC093 Beam Profile Monitor of the J-PARC 3GeV Rapid Cycling Synchrotron 1275
 
  • K. Satou, N. Hayashi, R. Saeki, A. Ueno, K. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • H. Harada
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima
  • S. Lee, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken
  • M. Tejima
    KEK, Ibaraki
  
  To obtain high intensity (1MW) and large emittance (214 π mm mrad) beam profiles of the 3GeV Rapid Cycling Synchrotron (RCS) of the J-PARC, we have developed the ionization profile monitors (IPMs) with wide active aperture and high dynamic range. It has three Microchannel Plates (MCPs) with active area of 81*41mm for signal multiplication and read out devices, and magnet system to generate guiding fields to collect electrons. The wide active aperture of ±116mm is obtained by arranging the three MCPs perpendicular to the beam axis. Furthermore, the dynamic range of 104 level can be obtained by adjusting each bias voltage of the MCPs. The IPMs are now collecting ions without the guiding fields. The beam commissioning of the RCS has been in progress since last year. The horizontal and vertical profiles are of great help, particularly to check injection errors. At the conference, the present status of the IPM system and the latest beam profiles will be reported.  
TUPC034 Beam Instrumentations for the J-PARC RCS Commissioning 1125
 
  • N. Hayashi, S. Hiroki, R. Saeki, K. Satou, R. Toyokawa, K. Yamamoto, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • D. A. Arakawa, S. Hiramatsu, M. Tejima
    KEK, Ibaraki
  • S. Lee, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken
  
  A 3-GeV Rapid-Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) has been commissioned recently. During its beam commissioning, various beam diagnostic instrumentation has been used. The multi-wire profile monitor (MWPM) is used to establish injection and H0 dump line, which transports un-stripped H- or H0 beam to the dump. The electron catcher confirms that the beam hits a charge exchange carbon foil and the specified current monitor limits the beam current to the H0 dump. Single pass BPMs which detect linac frequency (324MHz) and ionization profile monitors (IPM) help to check the one pass orbit without circulation of the beam. The beam position monitor (BPM) can measure both COD and turn-by-turn position. Tune monitor system consists of exciter and its own BPM. The exciter shakes the beam and coherent oscillation is measured at BPM. Dedicated BPMs, Fast CT (FCT) and Wall Current Monitor (WCM) are used for RF feedback or feedforward control. It will describe the performance of each instruments and how they are contributed to the successful beam commissioning.  
TUPC035 The Beam Position Monitor System of the J-PARC RCS 1128
 
  • N. Hayashi, S. Hiroki, R. Saeki, K. Satou, R. Toyokawa, K. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • D. A. Arakawa, S. Hiramatsu, M. Tejima
    KEK, Ibaraki
  • S. Lee, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken
  
  The Beam Position Monitor (BPM) system of the J-PARC RCS has been fabricated, installed and operated successfully during the beam commissioning. There are 54 BPMs around the ring and most of them are placed inside steering magnets. The BPM is electro static type and it has four electrodes. A pair of electrode gives a linear response with diagonal cut shape and they were calibrated before their installation. The signal processing unit, which is equipped with 14-bit 14MSPS ADC and 600MHz DSP, has been developed for the system. In order to measure small signal, especially during the initial phase of the commissioning, careful design also done for cabling. The paper presents the current performance of the system.