The Influence of Irradiation Temperature on the Thermoluminescence Response of Rock Salt Irradated in the MGy Range

Abstract

The effect of irradiation temperature on the thermoluminescence response of two types of rock salt is described. For experimental purposes an industrial irradiator, consisting of several sources of 60 Co with an activity close to 300,000 Ci, was used. This facility permitted integrated doses close to 1 MGy (981 kGy). To fulfil the research objectives a special heating system was designed and constructed, which maintains a constant temperature between -15°C and 200°C. The temperatures of the experiments were fixed constant at 60°C, 100°C, 140°C and 170°C These temperatures were selected after a detailed study of the results of the radiation-induced damage arising from a mathematical model (modified Jain-Lidiard model). Those results showed a large influence of the irradiation temperature on the radiation damage. Thermoluminescence studies have shown differences of one order of magnitude depending on the mineralogical composition of the samples. Furthermore, the TL maxima partially agree with the model predictions. The fading effect, which has also been studied at room and irradiation temperature, is enhanced at temperatures higher than 100°C. Optical absorption spectroscopy measurements are consistent with TL results. The aforementioned study complements the results reported previously of the effect of dose rate on the thermoluminescent response of rock salt.