A Real Time Wide Energy Range Personal Neutron Dosemeter with Two Silicon Detectors

Abstract

A real time personal neutron dosemeter was developed by using two types of silicon p-n junction detectors, Type A and Type B, fabricated by Fuji Electric Co. Ltd. The Type A detector is a 10B(96% enriched) doped silicon detector with a polyethylene radiator and a polyethylene moderator. The Type B detector is the usual silicon detector with a polyethylene radiator. The neutron responses of these two detectors to thermal neutrons and monoenergetic neutrons of five energies from 150 keV to 15 MeV were measured in a free air field and attached to a water phantom. No experimental data for the neutron responses could be obtained between thermal and 150 keV because of the lack of a monoenergetic neutron source; the neutron response from thermal to 15 MeV energy was calculated using the MORSE Monte Carlo code. It was found that the combination of two detectors gives a rather flat response for dose equivalent from thermal energy to 15 MeV, excluding a drop from 100 keV to 1 MeV, when attached to a phantom. This new type of dosemeter may be quite promising as a dose equivalent counter, since it is insensitive to gamma rays of ambient dose equivalent up to 0.2 Sv.h-1(20 R.h-1) and has low angular dependence from 0 to 45 deg.