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Hayashi, Naoki; Yoshimoto, Masahiro; Moriya, Katsuhiro; Hatakeyama, Shuichiro*
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1096 - 1100, 2019/07
It is necessary to understand the reason why the accelerator has been interrupted due to beam loss or other machine mal function in order to keep high availability in long term period. At J-PARC RCS, 25 Hz rapid-cycling synchrotron, there is a system to record beam intensity and beam loss monitor signal for all pulses with 10 ms period. At this time, in addition, new system to archive data with better time resolution if interlocked events occurred has been introduced. Using these archived data, the events only RCS BLM gives MPS have been analyzed and it turns out that these events are related to the ion source discharge which makes very low intensity within less than a second. In this paper other typical events are presented and discuss how to improve the accelerator performance in future.
Yamamoto, Kazami
Proceedings of 4th International Beam Instrumentation Conference (IBIC 2015) (Internet), p.80 - 84, 2016/02
The 3 GeV rapid cycling synchrotron of the J-PARC accelerates a proton beam up to 3 GeV and delivers it to the main ring and the material and life science facility. The main magnets (dipole and quadrupole magnets) of the synchrotron have large aperture, and thickness of yoke is larger than 200 mm. Considering the stopping power of a proton, a shielding effect of the magnets for beam loss monitor strongly depends on the lost beam energy. When the beam loss occurs during injection, the lost proton cannot penetrate the magnet yoke. But when the beam loss occurs after acceleration, lost beam easily pass the magnet. Therefore the signal response of the beam loss monitor is changed by the lost energy. We estimated the signal dependence on the lost energy by the simulation. The results indicated that the response strongly depends on the location of the lost point and lost energy. It is proportional to the lost power except the condition that the magnets become the radiation shielding.
