A new multistage etching method for calibration of CR-39 nuclear track detector for alpha particles spectroscopy

In this paper, application of the CR-39 passive nuclear track detector for spectrometry of alpha particles is investigated. To this end, a standard Am-241 source as the alpha radiation source, and brass collimators with different heights for energy determination of alpha particles were utilized. The detectors were irradiated by alpha particles in the energy range of 0.8 to 4.8 MeV and then were etched by sodium hydroxide solution in the temperature of 85 ℃ based on the multistage etching process with 1.5 hr etching time intervals. The experimental results showed that by increasing the etching time, the maximum track diameter happens in the higher energies of alpha particles. Owing to the occurrence of the overlap effect in the “alpha energy-track diameter” curve for insufficient etching times, experiments were carried out to define the minimum required time for efficient spectrometry over the alpha energy range of 0.8 to 4.8 MeV. It is shown that by increasing the etching time to 10.5 hr the overlapping effect can be overcome for the mentioned energy range and a practical diagram for alpha particles spectrometry in unknown fields can be obtained. Also, the detection efficiency of this method for alpha particles was measured to be near 100%.