Towards a prediction of long-term anomalous fading of feldspar IRSL

Anomalous fading of the infrared stimulated luminescence in feldspar is described by a new equation in which the unwanted loss of luminescence is given as a function of three variables, the measured fading rate, the laboratory radiation dose rate, and the environmental radiation dose rate. This equation is labelled dose rate correction (DRC) and it is tested on (a) young sediment samples for which the radiation growth curve is in the linear part of the dose-response curve, and (b) geologically old sediments in luminescence field saturation. Most of the experimental results are consistent with predictions that can be deduced from this equation. Given the common range of dose rates in luminescence laboratories and in natural soil environments, the time necessary for the unstable luminescence generated by artificial irradiation to fade away is predicted to be ca. 10(4)-10(5) years. (C) 2003 Elsevier Science Ltd. All rights reserved.