Monitoring of the injected beam to the J-PARC RCS and BPM design for H0 dump line

Hayashi, Naoki  ; Saha, P. K.   ; Yoshimoto, Masahiro  ; Hatakeyama, Shuichiro

The J-PARC Rapid-Cycling Synchrotron (RCS) is designed as an 1-MW high power accelerator. It has been operated since 2007, and its injection energy and beam current are upgraded in 2014. Its operation is very smooth and provides the high intensity beam to the Material and Life science experimental facility (MLF) and the Main Ring (MR). The beam is injected with multi-turn mode. It is possible because the negative hydrogen ion beam from the Linac, H, and the circulating proton beam H are different state. The H is converted to H at the injection point, where a charge stripper foil is set. A small fraction of the injected beam, which is not fully stripped, are transferred to the injection beam dump through H0 dump line to prevent un-necessary activation. Since the limit of beam dump is only 4 kW, which is about 3% of designed injection beam power 133 kW, the beam has to be stopped immediately in case of stripper foil break up incident.