Experimental study on radiation streaming through a labyrinth in a proton accelerator facility of intermediate energy

A radiation streaming experiment has been carried out at the Takasaki Ion A ccelerator Facility for Advanced Radiation Application at the Japan Atomic Energy Research Institute in a room housing a Cu target irradiated with 68 MeV protons and in a labyrinth of three-legs having a total length of 29 m. In the experiment, neutron and gamma ray energy spectra, neutron reaction rates, and neutron and gamma ray dose equivalent rates were measured using various counters and dosimeters. The experimental data show the applicabili ty of some empirical formulas for estimating the thermal neutron flux in a room and neutrons streaming in a labyrinth designed for a proton accelerato r operating in the intermediate energy region. The data suggest that it is mandatory to estimate the gamma ray dose equivalent rate in a labyrinth, wh ich is dominated by the secondary gamma rays due to the neutron capture rea ction.