γ-Radiation-induced sensitization, supralinearity, and photostimulated thermoluminescence in LiF TLD-100. Correlation studies

With decreasing post-annealing temperature in the region 300 to 220 °C, the sensitization factor of TL glow peak 5 in LiF TLD-100 is found to decrease systematically from a value of 8 to 3. This is accompanied by a marked increase of intensity of the residual TL peaks occuring in the region 250 to 320 °C. This is a positive indication of the conversion, on thermal annealing, of trap centres responsible for the residual TL to those responsible for the sensitisation. The mechanism of sensitization is otherwise similar to that proposed by Nink and Kos. The sensitization factor of peak 6 (250 °C) is found nearly 3.5 times higher than that of peak 5 (195 °C). This observation confirms Attix's theory of increased range of hole migration at higher temperatures. The model of Kos and Nink, after taking into account the influence of residual TL at low postannealing temperatures, is found to explain satisfactorily the photostimulated TL in LiF. The increased supralinearity of photo-TL as compared to the TL due to γ-rays is attributed to the difference in the relative spatial distribution of trap centres and luminescence centres.