Quadratic parametrization of the maximum alpha track lengths in CR-39 detector for various energies and incident angles

Abstract

CR-39 is a widely used solid-state nuclear track detector for alpha-particle detection. In this study, the alpha-particle range was investigated for various incident energies and angles using Geant4 Monte Carlo simulations. The maximum track length was measured and found to exhibit a quadratic dependence on the primary energy of the incident alpha particles. Additionally, the distribution of maximum longitudinal length as a function of particle energy revealed that the critical detection angle for alpha particles in CR-39 is 71° for a chemical etching solution of 6.25 N NaOH at 70 $\pm 0.1$ °C. For a minimum etching time of 40 min, required for track visualization under an optical microscope, the energy threshold ranges from 0.191 ± 0.001 MeV for normally incident particles to 10.87 ± 0.02 MeV for a dip angle of 71°. In the context of radiation level monitoring using CR-39, the optimal chemical etching time for reliable track density measurement is 400 min. Under this condition, the energy threshold varies between 3.13 ± 0.01 MeV for normal incidence and 14.3 ± 0.2 MeV at 70°. Notably, for incident angles of 71° or greater, no detectable tracks are observed at this etching time.