Performance of the beam collimation system in the J-PARC RCS

Yamamoto, Kazami   ; Kato, Shinichi*; Harada, Hiroyuki  ; Yoshimoto, Masahiro  ; Yamazaki, Yoshio ; Hayashi, Naoki  ; Saha, P. K.   ; Hotchi, Hideaki  ; Kinsho, Michikazu  

The most important issue in a high-intensity proton accelerator is achieving low beam loss operation in order to keep the accelerator tunnel in a hands-on-maintenance condition. To achieve such a condition, a collimation system was designed and installed in the Japan Proton Accelerator Research Complex (J-PARC) 3GeV Rapid Cycling Synchrotron (RCS). The experimental results indicated that the RCS collimation system performs well enough such that nearly all the ring components are maintained in good condition. However, as the beam power increased, unexpected losses downstream of the injection foil increased. Therefore, an additional collimator was installed that successfully reduced such unexpected losses.