Modelling thermal activation characteristics of the sensitization of thermoluminescence in quartz

The sensitization of the ∼110°C thermoluminescence peak in quartz, also termed the 'pre-dose' effect, was previously explained using an energy level model including two electron trapping states and two hole centres. The experimental procedure includes a stage of high temperature activation following a relatively large irradiation of the sample. The response to a small test-dose was found to depend on this activation temperature. With different quartz samples, different behaviours of the thermal activation characteristics (TACs) were found. In typical TACs, the sensitivity reached a maximum at ∼500°C, followed by a rather sharp decline in some samples; in others a maximum was reached at ∼350°C followed by a slight decline towards a plateau level. In this work, we show that these behaviours can rather easily be explained within the framework of the two traps-two centres model. This is done by numerical solution of the relevant sets of differential equations governing the different stages of the experimental procedure. The different kinds of dependence were simulated with different sets of trapping parameters. A better insight into the processes taking place is reached, which may have implications in the application of pre-dose dating of archaeological quartz samples and in retrospective dosimetry.