Abstract
The distribution of dose equivalents of neutrons and γ-rays emitted by the collisions of 35-MeV protons or 25-MeV deuterons with the copper of an analyser magnet, a chopper or a slit in the beam transportation room of the cyclotron building of Tohoku University were obtained by measurement with personnel monitors such as film badges, TLDs and CR-39 plastic track detectors. The CR-39 detectors were able to determine fast neutron doses without receiving disturbance of γ-rays. As for γ-rays, the readings with the film-badges were higher than those with the TLDs as much as about 20 to 30 percent. This might be due to the over response of the film badges for higher energy γ-rays (more than 1.25MeV). The doses of neutrons and γ-rays were greatly reduced by the stairs leading to the underground floor. The thermal neutrons showed almost the same values in the room except for the stairs.
