experimental and monte carlo studies on the response of cr-39 detectors to am-be neutron spectrum

background: the poly-allyl diglycol carbonate (padc) detector is of particular interest for development of a fast neutron dosimeter. fast neutrons interact with the constituents of the cr-39 detector and produce h, c and o recoils, as well as (n, α) reaction. these neutron- induced charged particles contribute towards the response of cr-39 detectors. material and methods: electrochemical etching was used to enlarge track diameter which was made by low energy recoil protons. before electrochemical etching, a chemical etching was performed for 1 hour. the responses were also calculated by monte carlo simulations, using mcnpx code in different energy bins considering h, c and o recoils. the total registered efficiency and partial contributions of the efficiency, due to interactions with each constituent of cr-39, were calculated. results: the optimized condition of etchant was obtained to be 6n koh 15kv.cm-1, and 6 hours etching time. the obtained results show that track efficiency of cr-39 was a function of incident neutron energy. the tracks caused by o and c recoil nuclei were negligible for neutron energies lower than 1 mev. at neutron energies lower than 1 mev, only recoil protons would have sufficient energy to leave visible tracks. but, o and c recoils had important contributions in overall response of padc at neutron energies of few mev. conclusion: the efficiency of a cr-39 based dosemeter could be calculated by mcnpx code and the results were in a good agreement with experimental results in energy range of 241am – be bare source and 241am-be was softened with a spherical polyethylene moderator of radius of 20 cm. iran. j. radiat. res., 2011 9(2): 95-102