Half-integer random resonance compensation for further beam power ramp-up in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

Kojima, Kunihiro ; Harada, Hiroyuki  ; Tamura, Fumihiko   ; Okita, Hidefumi  ; Chimura, Motoki  ; Saha, P. K.   

A comprehensive study on the random resonances was conducted to mitigate beam losses and ensure sufficient tunability of the operating point for further beam power ramp-up in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex. Low-intensity beam studies revealed considerable excitation of the half-integer random resonance. This half-integer random resonance was successfully compensated using trim quadrupole magnets without exciting other higher-order resonances. By implementing a conventional theoretical procedure based on resonance driving terms, we identified the leakage field from extraction magnets as the primary source of the error field driving the random resonance. High-intensity beam studies confirmed that our resonance compensation approach substantially mitigated beam loss in higher-tune regions, making it highly effective in improving operating point tunability.