Beam loss monitor system of the Rapid Cycling Synchrotron of Japan Proton Accelerator Research Complex

Yamamoto, Kazami   ; Hayashi, Naoki  ; Hatakeyama, Shuichiro; Saeki, Riuji; Iwama, Yuhei

The 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton AcceleratoR Complex (J-PARC) provides more than 300 kW beam to the Material and Life Science Facility (MLF) and the Main Ring (MR). In such high intensity hadron accelerator, the lost protons that are a fraction of the beam less than 0.1% cause many problems. Those particles bring about a serious radioactivation and a malfunction of the accelerator components. Therefore, the beam loss monitor (BLM) is one of the most important equipment to observe the state of the beam during operation, and to keep a steady operation. Moreover, if we set operation parameters of BLM adequately, it can detect the beam loss that is 10 fraction of the beam. Thus it enables fine-tuning of the accelerator. In the J-PARC RCS, a proportional counter and a plastic scintillation counter are used for the beam commission and the stable operation as BLM. We report present status of the BLM system in J-PARC RCS.