Radiation-induced modifications on spectroscopic and thermal properties of CR-39 and SR-90 nuclear track detectors

CR-39 and SR-90 polymer samples were irradiated with gamma-rays at high doses ranging from 5 x 10(4) to 4 x 10(5) Gy. Irradiation effects were studied using Fourier Transform IR spectroscopy (FT-IR) in transmission mode, ultraviolet-visible spectroscopy and thermo-gravimetric analysis. Besides production of carbon dioxide due to polymerization and irradiation processes observed by FT-IR spectrometer, the IR absorption spectra of the fresh (non-aged) and irradiated samples also show the presence of a strong new absorption band at 2273 cm(-1) which is attributed to the gaseous products inside the plastic. Moreover, the IR spectra indicate that on irradiation there is a change in the intensity and the shape of the OH group absorption bands relative to the unexposed sample. Optical absorption of CR-39 is influenced by the irradiation dose, while for SR-90 it was found to be an inverse function of higher doses. The thermal stability of these polymeric detectors shows considerable changes due to irradiation. The present study reveals that gamma-ray irradiation is more effective in the build up of new structures in SR-90 than CR-39 due to the damage that depends on the radiation fluences. (c) 2005 Elsevier Ltd. All rights reserved.