Thermally assisted photo transfer OSL from deep traps in Al2O3:C grains exhibiting different TL peak shapes

Abstract

The present work studies the thermally assisted photo transfer OSL (TAPT OSL) signal in the case of Al2O3:C samples showing double-structured main dosimetric TL peaks. The measurement signal provides indirect experimental evidence regarding the presence of deep traps along with one transfer mechanism extremely powerful and efficient. The experimental features of this signal are presented along with those yielded for samples with narrow TL peaks for the sake of comparison. In the framework of a dosimetric characterization, the straightforward relation observed between the TAPT OSL integrated intensity and the dose, even if non-linear, implies that this signal could be effectively used towards dosimetry purposes in the high dose region up to 250Gy. Furthermore, the study on the influence of the annealing temperature on the TL glow curve shape on Al2O3:C grains is attempted. The variety of glow curve shapes reported especially in the case of single grains is not affected by high temperature annealing, since its effect is dominant even after heating at 1085°C. Thus, this variety should not be correlated to the different deep trap occupancies, but rather be attributed to a possible structural defect. The main dosimetric TL peak af all grains is considered to be a composite of two unambiguously different traps of non-first-order kinetics. The low temperature part of these traps, reaching a maximum at ∼190°C is an electron trap and the high temperature part with maximum at ∼250°C is a hole trap. TL dose response of Al2O3:C grains presenting double peak structures is presented for the first time in literature, suggesting the usefulness on the applicability of Al2O3:C in the dose regime up to 100Gy.