Development of alpha tracks and neutron-induced recoil protons in CR-39 for dosimetric applications

Abstract

In the present work, CR-39 plastic detectors have been used in alpha and neutron detection studies. Detectors were first treated chemically, before irradiation, for background reduction and registration efficiency improvement. CR-39 detectors etched pre-chemically in 6.25N NaOH solution at 70°C for 10 h were found to be necessary to minimize the background tracks.

Alpha tracks were treated chemically and electrochemically and the distribution of the electric spot diameter has been studied at different values of high voltage and etching durations using our previously constructed electrochemical etching system. CR-39 foils were also exposed to various neutron doses from 0.17 to 4.0 rem using 5.0 Ci ²⁴¹ Am-Be source. A study of recoil proton tracks in CR-39 detectors have been performed under different conditions of etching. The average detector sensitivity to neutron-induced proton track registration was found to be about 21.0 ± 7% track cm⁻² mrem⁻¹. Result of the present work reflected the feasibility of using the CR-39 detectors as fast neutron dosimeter through the measurement of recoil proton track density.

Key Words:

• CR-39 detectors
• alpha tracks
• neutron dosimetry