Improvement of response of CR-39 nuclear track detectors in fast neutron dosimetry

CR-39 in combination with (n,p) radiators is used in routine fast neutron dosimetry. This material is highly sensitive to charged particles. Its application is restricted due to a high lower limit of detection caused by the large scattering from the background even from badge to badge of a single manufacturer. For its improvement it is necessary to investigate the etch process in detail. CR-39 was chemically and electrochemically etched in NaOH. The response to protons as the track generating particles in neutron dosimetry was measured as a function of the angle of particle incidence in the energy range up to 7.5 MeV. Appropriate proton beams were produced by Rutherford backscattering of accelerator particles. By means of a special evaluation technique the influence of stray particles was reduced. The curve of the critical angle of incidence for proton detection as a function of energy was determined experimentally. It can now serve as a basis for neutron response modelling.