Simulation of the effects of the dose rate and temperature on zircon thermoluminescence

Abstract

After exposure to ionizing irradiation, mineral zircon exhibits thermoluminescence (TL), which can be used to calculate the irradiation dose and the age of natural samples. Different aspects of the dating procedure based on zircon TL, including laboratory added irradiation at room and elevated temperatures, fading and preheat processes, have been considered within the framework of the kinetic model developed by our group earlier. It is shown that dose rate effects arising due to the difference between natural and laboratory irradiation can be removed by a suitable preheat treatment of the laboratory irradiated samples prior to the TL measurements. We demonstrate that the TL behaviour of zircon which has been irradiated under natural conditions can be reproduced by means of laboratory irradiation at some elevated temperature. This opens a promising possibility of (i) getting rid of dose rate effects and anomalous fading and (ii) reconstructing the dose dependence of the total TL signal emitted by samples irradiated under natural conditions. The model has been checked by simulating the dating procedures used for our coastal dune sand samples from Ameland (NL), the age of which is known from historical records; the results agree well with the available experimental data. The results of this investigation demonstrate the utility of the kinetic model for planning dating experiments and for development of new and innovative TL dating methods.