1-MW beam operation at J-PARC RCS with minimum beam loss

Saha, P. K.   ; Harada, Hiroyuki  ; Okabe, Kota  ; Okita, Hidefumi  ; Shobuda, Yoshihiro   ; Tamura, Fumihiko   ; Yamamoto, Kazami   ; Yoshimoto, Masahiro  ; Hotchi, Hideaki*

In the 3-GeV RCS of J-PARC we have performed a systematic experimental studies and numerical beam simulations to minimize the beam loss at the designed 1 MW beam power. We have optimized and modified both longitudinal and transverse injection paintings and succeeded obtaining a significant beam loss mitigation throughout the RCS. The beam loss at the collimator and the 1st arc section is reduced to be as much as more than 60% as compared to that using original painting methods. The residual beam loss at 1 MW is estimated to be as low as well below than 0.1%, which is dominated by the beam loss caused by foil scattering of the circulating beam. As a result, we obtained a very stable user operation of the RCS with nearly 1 MW beam power to the MLF with low beam loss and less machine activation.