Radiation shielding design for treatment room of HIMM

To guarantee the radiation safety of heavy ion medical machine (HIMM) during operation, the prompt neutron source term was calculated with the FLUKA code, and the effects of secondary neutron and gamma radiation on shielding were analyzed. The semiempirical formula and FLUKA code were adopted to calculate the shielding thickness, and the shielding design of HIMM treatment room was given. At the condition of full power operation of HIMM, the measured neutron dose rate is in agreement with the simulation result. The results indicate that the calculation method is reasonable, and the result is in accordance with the requirements of the national standard. (authors)