Kinetic simulation of the optical absorption dose response of LiF:Mg,Ti (TLD-100) incorporating spatially correlated electron and hole trapping centers

Abstract

A conduction band/valence band (CB/VB) model incorporating a spatially-correlated trapping center/luminescent center (TC/LC) complex is described which is associated with composite glow peak 5 in the thermoluminescence (TL) glow curve of LiF:Mg,Ti (TLD-100). The evidence for such a complex observed in the TL characteristics of TLD-100 is reviewed. Additional experimental evidence from the optical absorption (OA) energy spectrum and dose response of the individual bands has recently been reported in which the 4.0eV band is interpreted to arise from two sub-bands at 3.84eV and 4.3eV. The 3.84eV band demonstrates the commonly observed linear/exponentially saturating dose response and is interpreted to arise from the e-only TC which is not spatially correlated with an LC. The 4.3eV band is interpreted to arise from two sub-bands which are unresolved in the OA spectrum but which show two very different dose-response characteristics. The first arising from the TC/LC which has captured only an electron (resulting again in a linear/exponentially saturating dose response) and the other from an electron-hole captured configuration which continues to increase in concentration up to the highest levels of dose investigated. The CB/VB model is used to simulate the kinetics of charge carrier transport and capture leading to the dose response of all the observed OA bands.