State-of-the-art beam loss minimization at high intensity beam operation of the 3 GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

Saha, P. K.   ; Harada, Hiroyuki  ; Tamura, Fumihiko   ; Okabe, Kota  ; Yoshimoto, Masahiro  ; Shobuda, Yoshihiro   ; Okita, Hidefumi  ; Kojima, Kunihiro ; Nakanoya, Takamitsu  ; Hatakeyama, Shuichiro; Takayanagi, Tomohiro   ; Yamamoto, Kazami   ; Hotchi, Hideaki*

In this research, the beam loss in the J-PARC 3-GeV Rapid Cycling Synchrotron (RCS) has been significantly mitigated at the designed 1 MW beam power. It was possible by identifying all beam loss sources and implementing appropriate measures based on numerical simulations and systematic beam studies. The major one includes of using a smaller size charge-exchange foil and optimizing the injection beam to minimize foil scattering uncontrolled beam loss, modifications of the transverse and longitudinal beam painting parameters to mitigate the high-intensity effects. The beam loss as compared to 1 MW trial operation in 2020 was 80% reduced and perfectly localized at the designated collimator area. The beam loss power is only less than 0.1 kW as compared to the collimator limit of 4 kW. As a result. the residual radiation throughout the ring is substantially reduced for achieving a sustainable operation of the RCS with nearly 99% availability.