Delocalized recombination kinetic modelling of the LiF : Mg,Ti glow peak 5 thermoluminescence system

Abstract

TL kinetic theory based on delocalized recombination mechanisms is successful in predicting many characteristics of TL mechanisms when these are considered singly. However, the greater challenge of predicting a set of measured TL characteristics while using the same, or very nearly the same, parameter values has yet to be adequately addressed. In this work we apply delocalized kinetic modelling to describe four experimentally measured characteristics of the TL behaviour of peak 5 in LiF : Mg,Ti (TLD-100). These include: (i) optical absorption linear/exponentially saturating dose response of the appropriate OA bands with the experimentally measured dose filling constants; (ii) linear/supralinear TL dose response with f(D)max = 4–6 at a dose level of ∼400–600 Gy; (iii) constancy of Tmax with dose; (iv) agreement with the experimentally measured behaviour of Tmax and f(D)max with heating rate. We are successful in describing most of the details of these characteristics; however, we have failed to find parameter values which also correctly describe the dose response behaviour at low dose levels (preceding the linear, then the supralinear region) and the behaviour of f(D)max with heating rate. It is suggested that kinetic modelling based on a mixture of localized and delocalized recombination could successfully describe all the characteristics involved.