Neutron Dosimetry with CR-39 Track Detectors using Electrochemical Etching: Recent Improvements, Dosimetric Characteristics and Aspects of Routine Application

Abstract

Recent progress in improving the dosimetric properties of CR-39 etched track detectors is reviewed. With respect to the two-step electrochemical etching (ECE) technique the effects of electrical field strength and various radiator/absorber combinations on the neutron energy response were investigated in the energy range 144 keV to 14 MeV, showing agreement between experimental and theoretical results for the neutron response, if appropriate field strength dependent critical proton angles are used for calculation. Results of international intercomparison experiments show that with respect to energy response the ECE technique has already reached a certain level of optimisation. The energy response, angular dependence, response of CR-39 in contact with (n,a) radiators, dose range and lowest detectable dose are discussed. The results of long-term fading and changes in response and background are presented for commercial CR-39 materials manufactured by American Acrylics and Pershore Mouldings, which were stored over more than one year in air or nitrogen. The high scatter in response and background within the sheet and batch production, and thus the lowest detectable dose and the relatively small dose range, still limit the application of CR-39 in personnel monitoring.