I. Eliyahu

The modified unified interaction model: incorporation of dose-dependent localised recombination

The unified interaction model (UNIM) was developed to simulate thermoluminescence (TL) linear/supralinear dose-response and the dependence of the supralinearity on ionisation density, i.e. particle type and energy. Before the development of the UNIM, this behaviour had eluded all types of TL modelling including conduction band/valence band (CB/VB) kinetic models. The dependence of the supralinearity on photon energy was explained in the UNIM as due to the increasing role of geminate (localised recombination) with decreasing photon/electron energy. Recently, the Ben Gurion University group has incorporated the concept of trapping centre/luminescent centre (TC/LC) spatially correlated complexes and localised/delocalised recombination into the CB/VB kinetic modelling of the LiF:Mg,Ti system. Track structure considerations are used to describe the relative population of the TC/LC complexes by an electron-hole or by an electron-only as a function of both photon/electron energy and dose. The latter dependence was not included in the original UNIM formulation, a significant over-simplification that is herein corrected. The modified version, the M-UNIM, is then applied to the simulation of the linear/supralinear dose-response characteristics of composite peak 5 in the TL glow curve of LiF:Mg,Ti at two representative average photon/electron energies of 500 and 8 keV.

Thermoluminescence Theory and Analysis: Advances and Impact on Applications

Abstract Thermoluminescence (TL) refers to the emission of light during heating of a material previously excited by ionizing radiation. The TL mechanisms are described herein with the emphasis on the kinetic theory of trapping and recombination based on the energy bandgap model and the solution of multiple, non-linear, and coupled differential equations. These are used to simulate glow curve structure, dose–response, and activation energies. Linear/superlinear dose–response is explained on the basis of nanodosimetric concepts involving the joint electron–hole occupation of trapping center/luminescent center spatially correlated complexes. The major applications of TL (dosimetry and dating) are described as well as the modern methods of analysis of the TL signal.

Kinetic modeling of thermoluminescence, optical absorption and bleaching in LiF:Mg,Ti

In this paper we describe some aspects of our recent work which treats via kinetic simulations the experimentally observed linear/supralinear/saturating dose response of the thermoluminescence, optical absorption and behavior of optical bleaching at various photon energies in irradiated LiF:Mg,Ti (TLD-100) system in a physically realistic scenario. The results of the simulations are in good agreement with the experimental observations and this can be considered as a validation of the details of the proposed models.