Residual radiation dose at J-PARC linac

Kobayashi, Fuminori; Hirano, Koichiro  ; Ito, Takashi  ; Nammo, Kesao; Otani, Masashi*; Liu, Y.*

The linac of the J-PARC high-intensity proton accelerator accelerates negative hydrogen ion beams with a beam energy of 400 MeV and a peak beam current of 50 mA. The linac is installed in the accelerator tunnel, which is about 400 m long, and consists of an acceleration cavity, beam ducts, electromagnets, and beam monitors. During the operation of the accelerator, the accelerator components, the air in the accelerator tunnel, and the shielding concrete are activated by the H particles produced by the interaction of the beam particles with the residual gas in the acceleration cavity and beam duct and by the beam stripping caused by the interaction between the beam particles, in addition to the losses of the accelerated particles. Recently, the MLF beam power of 840 kW has been in service, and the beam intensity has been increased, so the trend of the residual dose in the linac accelerator is summarized and reported here.