Residual dose measurement and activation of the injection area in the J-PARC RCS

Yoshimoto, Masahiro  ; Yamakawa, Emi*; Takeda, Osamu; Yamamoto, Kazami   ; Harada, Hiroyuki  ; Saha, P. K.   ; Okabe, Kota  ; Kinsho, Michikazu  

In the 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC), we adopted the multi-turn charge exchange injection scheme using the stripper foils to achieve the high power proton beam. Therefore it is difficult to suppress the interaction between the stripper foils and the beam theoretically. And then, there are high residual dose around the stripper foil. From the measurements of the residual dose distribution and simulations using the PHITS, it is identified that secondary particles produced in the nuclear reactions with the foil had caused the high residual activity around there. And then, it was clear that the beam loss caused by the H particles which were converted from the injected H particles by the residual-gas stripping generates the localized high peak residual dose. In this presentation, we report the current status and the cause of the residual dose at the injection area in the RCS.