The effect of gamma spectrum on thermoluminescent dosimeter response

Abstract

The response as a function of photon energy, normalised to cobalt-60 gamma rays response, for the most used thermoluminescent dosimeters (lithium fluoride, lithium tetraborate, aluminum oxide, calcium sulphate and calcium fluoride) is analysed, for energies ranging from 0.010 to 1.25 MeV. A calculation method based on Burlin general cavity theory is used. The method is applied to obtain the response of thermoluminescent dosimeters for the case of spectra in 0, 5, 10, 20, 30 and 40 cm in water, irradiated by a cobalt-60 source plaque. The results show that, for the cases of lithium fluoride and lithium tetraborate, the response differs, respectively, by less than 1.3 and 0.2% from the response to cobalt-60 gamma-rays. For the other dosimeters the response differs significantly from that for cobalt-60 gamma-rays. In these conditions the deviation must be known or thin dosimeters should be used, which are nearly photon energy independent.