Author: Okabe, K.
Paper Title Page
MOPME020 Development of the New Measurement Method for the Incoherent Tune Spread and the Tune Shift Caused by the Space Charge Effect 512
  • S. Kato
    Tohoku University, Graduate School of Science, Sendai, Japan
  • H. Harada, H. Hotchi, M. Kinsho, K. Okabe
    JAEA/J-PARC, Tokai-mura, Japan
  For the high intensity accelerator, the incoherent tune which is the frequency of the individual particles is shifted and decreases due to the space charge effect. In addition, the incoherent tune is formed into spread shape commonly. When the incoherent tune satisfies a resonance condition, it might be occurred the beam emittance growth and the beam loss. So it is necessary to reduce the incoherent tune spread and the tune shift as much as possible. To achieve this condition, it is desired to measure the incoherent tune spread and the tune shift directly. Therefore we are developing the new measurement method of the incoherent tune spread and the shift due to the space charge effect. From the simulation results, it was cleared that the beam distribution can be modified in the case of using the mono frequency dipole exciter because a particle which has the tune corresponding to the exciter can be resonated temporary. In addition, it was cleared that it is possible to evaluate the incoherent tune spread and the tune shift by the measurement of the distribution transition. We present the outline of this method and the developing plane at the J-PARC RCS.  
MOPME028 A Preliminary Study of the Vibration Wire Monitor for Beam Halo Diagnostic in J-PARC L3BT 535
  • K. Okabe, M. Kinsho, K. Yamamoto, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  In the J-PARC 3-GeV Rapid Cycle Synchrotron (RCS), transverse beam halo diagnostic and scraping are required to increase the output beam power. Wire scanners and halo scrapers were used for measurement of projected beam distributions to determine the extent of beam halo formation at Linac-3GeV Beam Transport line (L3BT). In order to determine more detail of halo formation, Vibration Wire Monitor (VWM) was installed in L3BT for the beam halo measurement and the offline study at the test stand with low energy electron gun are started. The high sensitivity of the VWM makes it a prospective one for investigation of beam halo and weak beam scanning. In this paper, we will report a preliminary results of offline studies and beam halo measurement by VWM at L3BT.