Radiation damage in thermoluminescent LiF TLD-phosphor

Abstract

The thermoluminescence response to gamma rays of the most sensitive glow peaks in LiF (II to V) reaches a maximum and then decreases. The decrease in response is attributed to radiation damage. It is observed that even after the considerable reduction in the TL, which results from a heavy dose, the saturation exposure for these peaks remains the same. However, by redistributing the traps amongst the peaks by pre-annealing at 200 degrees C for 23 hours, the saturation exposure can be altered. Since saturation exposure is indicative of the availability of trap centres, it is suggested that radiation damage in LiF is due to a decrease in the luminescence centres. This decrease could be due to the aggregation of simple luminescent centres into complex centres. The possibility of the M-centre being one such centre is discussed.