Dependence of thermoluminescence sensitivity on temperature of irradiation in LiF (TLD-100) phosphor

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Abstract
A strong dependence of the intensity of the thermoluminescence (TL) output of peaks 5 (208 degrees C), 7 (266 degrees C) and 10 (422 degrees C) on temperature (Tirr) (in the range 25-295 degrees C) at which the phosphor samples were irradiated was observed in LiF (TLD-100) in the dose range covered by the authors (1.7*102-2.5*103 Gy). Below the dose level of 1.26*103 Gy, the intensity of peak 10 was 35-75% higher for high Tirr compared with the room-temperature (25 degrees C) irradiation. Above 1.26*103 Gy, a reversal was observed in which the decrement in TL intensity of peak 10 increased with Tirr. In general, the TL intensities of peaks 5 and 7 decrease with increasing Tirr. The effect of Titt on the sensitisation of peaks 5 and 7 was also studied. The sensitisation of peak 7 depends on the intensity of peak 10. The sensitisation of peak 5 at high Tirr is more than that at 25 degrees C for pre-doses below 1.26*103 Gy and a reversal is then observed from this dose onwards. The authors explain increase of TL intensity and S/S0 at high temperatures as due to increased elimination of competitors to luminescent centres. The decrease in the intensity of TL and S/S0 with increasing Tirr is explained as due to the increased radiation damage to luminescent centres.