The optical properties of CR-39 polymer track detectors irradiated with high Linear Energy Transfer (LET) (alpha particles at energies 3.05 MeV and 4.86 MeV) and followed by low LET (gamma ray irradiation at different doses ranging from 0 to 200 kGy) were investigated. The chemical etching was verified for all samples. Also, the optical properties were studied with an Ultraviolet-Visible (UV-VIS) spectrophotometer for the samples before and after etching. An absorption peak appeared at 208 nm in the UV spectra for the 4.86 MeV samples before etching. On the other hand, the track diameter measurements were satisfied for all samples. Moreover, the optical energy band gap was calculated for the samples before etching. The IR spectra for CR-39 samples (before etching and after 3 h etching time) were investigated. All of the three techniques may reveal the formation of new energy levels induced by radiations in CR-39 polymeric material. This study gives a possibility to using the CR-39 samples as a gamma ray dosimeter by the corresponding optical properties.
Keywords: CR-39 track detectors, optical properties, chemical etching, post-gamma ray irradiation, polymers, linear energy transfer, low LET, high LET, optical energy band gap, post-irradiation, low radiation, spectral response