Kinetic analysis of the 300 °C TL peak in Solonópole natural quartz sensitized by heat and gamma radiation

Earlier, the sensitization of a thermoluminescence (TL) peak near 300 °C in Solonópole quartz was investigated taking into account the combined effect of heat-treatments and irradiation with high doses of γ rays. At that time, it was shown that the sequence: heat at 500 °C, irradiation at 25 kGy and annealing at 400 °C, was a suitable procedure to measure doses as low as 0.1 mGy using this quartz. However, sensitization with doses higher than 50 kGy and the kinetic analysis of the 300 °C peak were not considered. The aim of the present study is to measure the TL sensitivity and the main kinetic parameters of this peak as a function of various sensitization conditions. Five lots of samples were sensitized at different heating temperatures and incremental doses up to 200 kGy. The activation energy was calculated by the peak-shape and the repeated initial rise methods. As a result, the decay noticed in TL sensitivity above 100 kGy was less intense for the lots that were heated before irradiation. The geometrical factor analysis was important to clarify the kinetic-order and the probability of retrapping for each condition of sensitization. The activation energies measured by each method are in fair agreement with each other and were mainly affected by the heat-treatment performed at 1000 °C before irradiation. Activation energies averaging (1.51 ± 0.06) eV were calculated for untreated and heat-treated lots at 500 and 800 °C.