Effects of annealing and high radiation dose on the thermoluminescence characteristics of natural fluorite

Abstract

In this study, the various dosimetric properties of the thermoluminescent (TL) phosphor of CaF2:natural including response characteristics, sensitivity to thermal annealing and decay of stored energy were investigated in detail. The analysis of the peak temperature values and the half widths of the resolved components in the glow curves, by using the Computerized Glow Curve Deconvolution (CGCD) Method, resulted in the activation energy (E) of 0.85-1.83 eV and frequency factor (s) of 6.17E+9-2.90E+15 s(-1). The effects of pre-irradiation thermal annealing on the radiation-induced sensitization of the thermoluminescent response of CaF2:natural were presented. An enhancement of sensitivity after being subjected to a high beta particle exposure was clarified. The effect was complicated by the influence of heat treatments before the exposure to radiation. Replicate runs on CaF2:natural after irradiation with 1 Gy absorbed dose indicated good reproducibility of peak temperatures and intensities; they can be re-used for repeated measurements. It appeared that the main dosimetric peak at 280 degrees C exhibits negligible fading over 4 weeks and may be used for dosimetry. This study has demonstrated that the potential exists for the use of CaF2:natural for TL radiation dosimetry. (C) 2012 Elsevier Ltd. All rights reserved.