Kinetic simulation of the effect of 3.6 eV and 4.2 eV photon excitation on the optical absorption energy spectrum of ¹³⁷Cs gamma irradiated LiF:Mg,Ti (TLD-100)

The effect of photon excitation on the optical absorption (OA) energy spectrum of LiF:Mg,Ti (TLD-100) following gamma ray irradiation to a dose-level of 2500 Gy are presented. Photon energies of 3.6 eV and 4.2 eV were chosen to selectively excite the trapping centers (TCs) associated with the 3.8 eV and 4.3 eV OA bands. The TCs associated with these OA bands are believed to give rise to the electron-only and electron-hole components of composite glow peak 5 in the thermoluminescence (TL) of TLD-100. Kinetic modeling is shown capable of simulating the changes in the optical density of the OA bands induced by the two photon energies with the same values of the recombination coefficients. This result is in contrast to a previous investigation which could not simulate the OA following both gamma irradiation and photon bleaching with the same values of the recombination coefficients. The results reported herein are consistent with: (i) the interpretation of the e-only and e-h charge configurations giving rise to the 3.8 eV and 4.3 eV OA bands and (ii) the possibility that the recombination processes following gamma irradiation occur not only following thermalization of the electron and hole charge carriers but at higher energies as well.