Thermoluminescence response of LiF to gamma rays

The thermoluminescence of lithium fluoride shows twelve peaks, of which II (1000C), III (1350C), and V (1900C) grow linearly first and then become nonlinear, eventually saturate and finally show decreased response or damage. Peaks beyond the Vth peak on the other hand seem to grow supralinearly right from the beginning. None of the available explanations for the supralinearity of the dosimetry peak (V) is entirely satisfactory. Similarly damage too is not understood. It has been shown that the radiation induced sensitization is linked with the XIIth peak (4000C). It is postulated that this peak is created as a result of irradiation and hence is supralinear right from the beginning. The other high temperature peaks, though supralinear, are not found to be responsible for radiation induced increase in sensitivity of lower temperature peaks. It is shown that the trap centers (TC's) responsible for the XIIth peak are generated as a result of the break up of complex centers TCLC's on irradiation. This break also causes the addition of luminescence centers (LC's) which leads to increase in sensitivity. The complex centers (TCLC's) themselves are formed due to the 4000C annealing. Decreased response or damage after saturation is the result of loss of luminescence centers while the traps remain unaffected