Proton-recoil neutron dosimeter for personnel monitoring.

Abstract

A personnel neutron dosimeter based on a CR-39 plastic track detector registering recoil protons has been developed. The sensitivity, energy response, angular dependence and fading characteristics have been measured. The sensitivity to AmBe neutrons is 22.7 tracks cm−2 mrem−1. The energy response was investigated both experimentally and theoretically. It was determined that neutrons having energies as low as 144 keV can be detected. The energy response curve (tracks cm−2 mrem−1) is uniform to within 30% between 0.2 and 20 MeV. However, at energies outside this interval, considerably larger departures from uniformity exist. The in-air sensitivity decreases as the neutron direction changes from perpendicular to glancing incidence. The sensitivity at glancing incidence is less than 5% of that at perpendicular incidence. Fading studies show that the dosimeter is stable at room temperature over periods of months. Background distribution studies show that the lower limit of detection is ∼10 mrem for a spectrum of AmBe neutrons.