Author: Miyao, T.
Paper Title Page
MOPAB068 Bunch Shape Monitor Development in J-PARC Linac 271
 
  • A. Miura, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  • Y. Liu
    KEK/JAEA, Ibaraki-Ken, Japan
  • T. Miyao
    KEK, Ibaraki, Japan
 
  At Japan accelerator reserch complex (J-PARC), the linac, which serves as the injector for the downstream 3-GeV synchrotron, accelerates a negative-hydrogen-ion beam (H) to obtain a 400-MeV beam energy. We use an accelerating frequency of 324 MHz for the accelerator cavities and of 972 MHz. Both the centroid-phase set point at the frequency jump from 324 MHz to 972 MHz and the phase-width control are key issues for suppressing the excess beam loss. In order to optimize a set point of the tuning cavities, we developed a bunch-shape monitor (BSM) to measure the phase width as well as a tuning strategy to minimize the beam loss. In the development of the BSM, the design developed in the INR, Russia. Because the BSM had first experienced to be used between accelearation cavities, we need to protect the leak-magnetic field from quadrupole magnets and outgas impacts to cavities. We installed a BSM again in the beamline, BSM started to measure the phase width and evaluated its performances with a peak-beam-current dependence. We proposed new strategy to use BSM-measurment data for the tuning cavity. This paper describes the BSM development, its modification, and new strategy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB068  
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MOPAB071 A Beam Position Monitor for the Diagnostic Line in MEBT2 of J-PARC Linac 281
 
  • A. Miura, Y. Kawane, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  • T. Miyao
    KEK, Ibaraki, Japan
 
  In the linac of the Japan Proton Accelerator Research Complex (J-PARC), the neutral hydrogen (H0) generation from the negative hydrogen ion (H) beam is one of key issues to mitigate the beam loss. In order to diagnose the H0 particles, we installed the bump magnets to make a chicane orbit of the H beam. To evaluate the horizontal shifts of the beam orbit, a beam position monitor (BPM) is fabricated. The BPM measures the shift-positions with various driving currents of the bump magnets. We employed the WSM to measure the H beam profile. It also help us to compare the shift-positions measured by BPM. In this paper, the design and the performance of the BPM is described. In addition, we describe how to compare the shift position.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB071  
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TUPVA096 Detection of H0 Particles in MEBT2 Chicane of J-PARC Linac 2308
 
  • J. Tamura, H. Ao, T. Maruta, A. Miura, T. Morishita, K. Okabe, M. Yoshimoto
    JAEA/J-PARC, Tokai-mura, Japan
  • K. Futatsukawa, T. Miyao
    KEK, Ibaraki, Japan
  • Y. Nemoto
    Nippon Advanced Technology Co., Ltd., Tokai, Japan
 
  In the Japan Proton Accelerator Research Complex (J-PARC), H0 particles generated by collisions of accelerated H beams with residual gases are considered as one of the key factors of the residual radiation in the high energy accelerating section of the linac. To diagnose the H0 particles, the new beam line for analyzing H0 and H particles was installed in the second medium energy beam transport (MEBT2), which is the matching section from the separated-type drift tube linac (SDTL) to the annular-ring coupled structure linac (ACS). The analysis line consists of four dipole magnets for giving the H beam chicane orbit, and a wire scanner monitor (WSM) for measuring the horizontal shift of the H beam. To detect the H0 particles, a carbon plate is installed to the WSM. In the beam commissioning, we detected the signals of H0 particles penetrating the plate and observed the transition of the signal with various vacuum condition in the SDTL section.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA096  
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