Study of gray level properties of alpha-particle tracks in solid-state nuclear track detectors

Abstract

In this paper, an investigation on the optical appearance of etched tracks from alpha particles with different incident angles and energies in solid-state nuclear track detectors (SSNTDs) was conducted. Optical properties such as gray levels, major and minor axes from experiments are considered as quantitative variables to distinguish among various types of tracks. The transmission operation mode of optical microscope was used for track observation. It was found that the gray level properties for the same tracks under different exposures varied to large extents. This can be corrected by finding the optimum operation conditions of the camera inside the microscope so as to obtain consistent gray levels. Gray level results and dimensions of major and minor axes were obtained for tracks from alpha particles in CR-39 SSNTDs, with incident angles ranging from 40° to 80° and incident energies from 1.5 to 4.5 MeV. Automation in differentiating among recorded tracks was done by using a self-developed program, for which the values of different optical properties are used as the inputs and from which the angle and energy of the incident alpha particles are given as the outputs. The findings show that using those optical properties can help in the determination of alpha energies with an accuracy of 0.5MeV. ± A comparison between the experimental results and the theoretical values from a test program using ray-tracing method based on geometrical optics was also made. It shows that the comparison in terms of dimensions of major and minor axes is more accurate than that in terms of average gray level.