A Study of the Effect of Etching Time on the Optical Properties of Irradiated CR-39 Polymer.

The track etch detector, CR-39, in common usage, is highly sensitive to recording charged particles. CR-39 polymer samples were irradiated with alpha particles at different energies (2.17 MeV and 3.95 MeV) followed by chemical etching with different times (1.50, 3.00 and 6.00 h). Tire tracks formed in CR-39 due to irradiations were visualized by using etching technique. The optical properties of the CR-39 polymer before and after the etching processes were studied with ultraviolet-visible (UV-vis) spectroscopy. The optical band gap energy was calculated for the CR-39 polymer samples. The average value of the track diameter of irradiation at 2.17 MeV and etching time 1.5 h is fairly large compared with its value at 3.95 MeV. This is due to the production of defect levels in the band gap of polymer at the 2.17 MeV. The results revealed that the CR-39 samples at 3.00 h are insensitive to the optical variations in the fundamental absorption edge. [ABSTRACT FROM AUTHOR]