Kinetic modeling of charge transfer following photon bleaching post-irradiation of spatially correlated trapping and luminescent centers in LiF:Mg,Ti

Abstract

Illumination of LiF:Mg,Ti by photons of energy 3.65 eV and levels of fluence from 1.2 1018 ph cm−2 to 3.6 1018 ph cm−2 results in a decrease of the thermoluminescence (TL) dose response supralinearity of peak 5 in the glow curve of LiF:Mg,Ti. No further effect on the dose response is observed at higher photon fluences up to 1.4 × 1019 ph cm−2. The threshold of dose response non-linearity usually reported at a dose of 1 Gy, is increased to 30 Gy. A kinetic model is described herein in the framework of conduction band/valence band solid state theory incorporating spatially correlated trapping centers (TCs) and luminescent centers (LCs). The model successfully simulates the bleaching action of the 3.65 eV photons on the increased region of TL dose response linearity as resulting from the depletion of the occupied trapping centers and to a lesser degree by charge transfer via the conduction band between the various configurations of the TC/LC system associated with composite peak 5.