FURTHER INVESTIGATIONS ON CR-39 FAST-NEUTRON PERSONAL DOSIMETER

A fast neutron personal dosemeter based on CR-39 nuclear track detecto rs has been developed in as simple a form as possible to be used in ro utine monitoring. It has been investigated during the last joint irrad iation exposures to neutrons organised by EURADOS-CENDOS committee on the application of track detectors in neutron dosimetry. The energy re sponse and the angle dependence of two types of CR-39 material, produc ed by Pershore Mouldings Ltd (as standard grade material) and American Acrylics (as dosimetry grade material), have been studied using neutr on energies ranging from 144 keV up to 66 MeV and the Cf-252 neutron s pectrum at different angles of incidence, i.e. 0 degrees, 30 degrees, 60 degrees and 85 degrees. Irradiated detectors have been processed us ing a conventional chemical etching (CE) and a two-step electrochemica l etching at low (200 Hz) and high (2 kHz) frequencies (ECE). Under th e ECE etching conditions a 80 mu Sv minimum dose equivalent value is a chieved. The response of these detectors to the ambient dose equivalen t in the range 0.4-13 mSv has also been studied for monoenergetic neut ron beams of 1.2, 5.3 and 15.1 MeV. The dosimetric characteristics of the proposed dosemeter have been much improved by using the ECE condit ions. The variations and values of these characteristics approach the required ones in a better way than that given till now in previous wor ks.