The Effect of Pre-Irradiation Heat Treatment on the Evaluated Trapping Parameters of LiF:Mg,Ti (TLD-100)

The effects of high ambient pre-irradiation heat treatment (125 deg. C) on the trapping parameters of the various thermoluminescence peaks of LiF:Mg,Ti (TLD-100) crystals have been investigated in detail by using computerised glow curve deconvolution methods. Deconvolution of glow curves to their individual glow peaks demonstrates that the application of a pre-annealing stage changes the trapping parameters significantly. Computerised peak shape analysis showed that the order of kinetics of peak 1 increases from 1.0 to 2.5 whereas the order of kinetics of other peaks remained constant during the heat treatment. After approximately 7 h of heating, a new peak as a shoulder on the low temperature side of peak 3 and a new peak at the high temperature tail of peak 5 were observed. Shifts of peak temperature of peaks 3, 4 and 5 to the high temperature side were also noted. Significant changes to the activation energies and frequency factors of all peaks, especially peak 4, start immediately and continue throughout the annealing period. These results indicate that important defect structure modifications take place not only in the glow peaks 2 and 5 but also in peaks 1, 3 and 4. (author)