Design and calibration of a passive detector for separating neutron, proton and $\upalpha$-particles in mixed radiation fields

Abstract

In this study, a new detector is designed based on CR-39, and separately calibrated for protons, neutrons and $\upalpha$-particles under the same etching condition. To that end, an americium–beryllium standard source (${}^{241}\hbox {Am--Be}$) and a plexiglass phantom for neutron irradiation, brass collimators and an americium standard source (${}^{241}\hbox {Am})$ for alpha irradiation, as well as a Van de Graaff accelerator for proton irradiation were employed. Sodium hydroxide solution of 6.25 N at $85^{\circ }\hbox {C}$ was also used for CR-39 chemical etching. Considering the detection principle of the device, different filters were designed to help distinguish between fast neutron particles, thermal neutrons, albedo neutrons, protons and $\upalpha$-particles in mixed radiation fields. Moreover, both the contribution of each particle and the ability of the designed detector to discriminate energy of charged particles were quantified.