Investigating the OSL Components and the Sensitivity Changes in a Natural Quartz Crystal Showing an Intense Post-Sensitization TL Signal

This study aims to investigate the optically stimulated luminescence of quartz grains exhibiting an intense thermoluminescent signal between 250 and 350 degrees C after sensitization with a high dose of gamma radiation and moderate heat treatments. Pellet discs produced with zeroed and sensitized grains were irradiated with test doses ranging from 0.5 to 40 Gy. After sensitization, the OSL signal of the fast component stimulated with blue light increased more than 1000 times. Annealing at 400 degrees C was adopted to erase the residual signal. The sensitivity changes were assessed after various TL and OSL readings. The annealing cycles were responsible for a significant increase in OSL and a 20% reduction in TL signals. The analysis of the residual TL indicated that the traps responsible for the main components of the sensitized peak (280 degrees C) are harder to bleach than those related to the so-called 110, 325, and 375 degrees C peaks. The sensitivity changes and the relationship between OSL and TL signals were explained in terms of a mechanism of competition involving active and deep electron traps. No correlation was observed between the fast OSL component and the 325 degrees C TL peak.