Initial sensitivity change of K-feldspar pIRIR signals due to uncompensated decrease in electron trapping probability: Evidence from radiofluorescence measurements

摘要

The poor dose recovery ratios reported for the infrared (IR) stimulated luminescence and post-IR IR stimulated luminescence (pIRIR) measurements of potassium feldspar (K-feldspar) have been attributed to the initial sensitivity changes. The change in electron trapping probability was inferred as a possible cause of the initial sensitivity change. However, there is still a lack of experimental evidence. In this study, the electron trapping probability changes were traced by recording the radiofluorescence (RF) emitted in the IR band (IR-RF) during the irradiation steps of the "single regenerative point" dose-recovery-like experiments. The IR-RF data shows that both high temperature heating and the preceding received dose during the laboratory measurements lead to a decrease in electron trapping probability for the sample employed in this study. For the pIRIR(290) signal, a 20% sharp decrease in the trapping probability is induced by the high temperature preheat, irrespective of the dose administered. For the pIRIR(225) and pIRIR(170) signals, the trapping probability decreases more gradually during the measurements for small doses and a 20% sharp decrease is only observed after the aliquot was irradiated with a large dose. The decrease of trapping probability does not always lead to initial sensitivity change. We infer that the heating and dosing may induce an increase in recombination probability, which serves as a compensation mechanism to balance out the trapping probability decrease. The amplitude of recombination probability increase may decrease with the increase of dose, and therefore, the occurrence of initial sensitivity change shows dependence on the type of pIRIR signal and the size of given and test doses.