A TL model based on deep traps competition

Abstract

TL appears as a very complex phenomenon. However, some general features are widely presented by TL materials: low TL yields, nonlinear growth with dose (supralinearity or saturation), lower efficiency for high LET particles etc., which are not explained by the well-known classical one-trap band model. In the past, the competition between TL traps and deep (thermally disconnected) traps was proposed in theoretical models accounting for some specific TL features. Arguments are presented here for a more general role of deep traps, in order to get an overall satisfying (at least qualitatively) description of the TL phenomenon either in the irradiation stage (TL or ESR) or in the heating one. A corresponding theoretical model is proposed. It is outlined that the competition between TL and deep traps leads to spatial correlations between electrons in TL traps and recombination centres (trapped holes). On the other hand, occurrence of recombination is taken into account as well in the irradiation step as during the heating one. As a result, on a very simple basis, the model accounts for supralinear behaviour of TL output with dose, non-exponential shape of TL or ESR growth curves, slight temperature shift of glow peaks with dose and scarceness of observed second-order kinetics.