New pre-soaking technique for PADC and application to wide-range personal neutron dosimeter

摘要

Poly allyl diglycol carbonate (PADC) plastic has been widely used as one of most sensitive detectors for personal neutron dosimeter. However, a considerably large number of false pits, which are very difficult to he distinguished from etched tracks induced by neutrons, appear even on the surface of non-irradiated PADC plastic. We have developed a new pre-soaking technique where PADC is soaked in a chemical solution before etching process. Owing to this procedure, the number of false background pits could be successfully reduced by one tenth compared with that for non-treated PADC samples. We have also applied this improved type of PADC practically to personal neutron dosimetry, coupled with a polyethylene sheet for fast neutrons in MeV region and a boron nitride sheet for lower energy neutrons. The measured detection efficiency of the dosimeter mounted on the water phantom was compared with results calculated by Monte Carlo simulation using the MCNP4C2 code. It was confirmed that the energy response of the dosimeter evaluated by the sum of etch-pits on two regions would agree well with the energy dependence of the neutron-fluence to personal-dose-equivalent conversion coefficient given by ICRP Publication 74. (C) 2008 Elsevier Ltd. All rights reserved.