A fast-neutron dosimeter with nearly flat dose equivalent response using CR-39 detectors with various combinations of radiators

CR-39 foils of thickness 500 μm placed behind several combinations of radiators, have been irradiated with monoenergetic neutrons of energies ranging from ∼ 100 keV to ∼ 19 MeV at normal incidence from a Dynamitron accelerator. The dose equivalent response of the detector has been studied by using conventional pre-etching followed by electrochemical etching. The results obtained are compared with calculated values. The thicknesses and compositions of the radiators are chosen so as to suppress the CR-39 response below ∼ 4 MeV by preventing the recoils of hydrogen nuclei, out of the hydrogen-rich radiators, from reaching the post-etch surface of the detector. When 27Al and 56Fe are used as primary radiators, they contribute towards the enhancement of the detector response for neutron energies above ∼ 6 MeV through (n, p) and (n, α) reactions, while the thickness of the configuration suppresses the response below ∼ 4 MeV. (author)