Thermoluminescence response of CaF2:Dy as a function of irradiation temperature between room temperature and 270 °C

Abstract

The Themoluminescence (TL) response of CaF2:Dy (TLD-200) as a function of irradiation temperature was studied in the present work. The irradiation of a TL material at elevated temperatures has a twofold scope: (a) To provide knowledge and insight regarding the possibilities of radiation dosimetry at high temperature environments; (b) The fact that during irradiation at elevated temperatures trap filling and trap emptying take place simultaneously, makes this pre-conditioning the most promising for the reflection in the net glow-curve of competition effects between traps and centres. The irradiation temperature (Tirr) region was between room temperature (RT) and 270 °C in steps of 10 °C. Using the same conditions as far as dose and temperature are concerned, post irradiation annealing (PIA) measurements were also performed, which give only the results of trap emptying. Both experiments were performed using (a) one sample for all measurements (single-aliquot procedure) and (b) two samples for each temperature (multi-aliquot procedure). Deconvolution was also applied in all cases towards investigating the impact of the two protocols on the kinetic parameters of all peaks for this specific material. The results showed that there is not any dependence of the TL response in the case of multi-aliquot procedure. However, in the case of single-aliquot procedure, a very interesting dependence of the TL response on Tirr is observed only for the last TL peak of TLD-200. These results, although weaker, were also observed in the case of PIA procedure. Activation energies of the high-temperature, more stable peaks yield a dependence on both irradiation and PIA temperatures. The results are discussed in the framework of the trap competition models.