Neutron dose rate in the facility at the Cyclotron Center of Chung Shan Medical University

The neutron dose equivalent rate (DR) leaking from the self-shielded cyclotron was measured using an FHT-751 neutron counting system in the facility at the Cyclotron Center of Chung Shan Medical University. This system was calibrated using two 252Cf neutron sources and simulated according to MCNP code. The results show various DRs up to 120 μSv h-1 in the cyclotron room. Two-dimensional distributions of measured neutron DRs indicate an explicit, heavy leakage of neutrons through the self-shielded interlock. The neutron DR of the operating cyclotron that is hazardous to the health of medical personal and the public is evaluated.