OSL and photo-transferred TL of quartz single crystals sensitized by high-dose of gamma-radiation and moderate heat-treatments

This study investigates the optically stimulated luminescence (OSL) and the photo-transferred thermoluminescence (PTTL) signals in quartz single crystals showing a strong TL peak near 300 °C after being sensitized by irradiation with 25 kGy of gamma rays and heating at 400 °C. Natural and sensitized samples were prepared from two crystals with different sensitivity levels in the 300 °C TL region. Continuous-wave (CW) and linearly-modulated (LM) OSL signals were stimulated with blue light-emitting diodes during 40 and 1000 s, respectively. Two components were isolated from the CW-OSL signals of sensitized samples. These components were clearly seen in LM-OSL measurements together with two long-term components. LM-OSL showed that the sensitization process considered in this study sensitized an ultrafast OSL component of these crystals. The similar behavior found for the thermal stabilities of OSL and TL signals and the dependence of these signals with sample origins suggested that the trapping site related to the ultrafast component is also related to the TL process of the sensitized peak. The PTTL signal induced by blue LEDs increased the intensity of the sensitized glow peak. On the other hand, a remarkable reduction in the intensity of this peak as a result of the accumulated effect of blue light exposure was clearly seen in both kinds of crystals. These results were explained by a mechanism of competition between optically unstable deep traps and trap levels responsible to the sensitized TL peak.