Determination of thermoluminescence kinetic parameters in polymer pencil lead graphite under photon exposures

This study performed thermoluminescence (Tl) measurements of polymer pencil lead graphite (PPLG) with varying temperature from 100 to 300 K and heating rates from 2 to 10 °C. From the analysis of both initial rise and curve fitting methods, the principal trap parameters of PPLG were determined by analysing its Tl properties under photon dose range of 0.5 Gy to 200 Gy. The trap parameters include the order of kinetics, the activation energy, the frequency factor, and the initial concentration of trapped electrons. The Tl glow curves (the plot of light emitted with time/temperature) provides information on the physical parameters of the defects participating in luminescence process. Relevant Tl glow curves were de convoluted to restore the original signal and then fitted using advanced software. From the fitted Tl signals, the trap parameters of the individual peaks were numerically determined. The fading, the post-irradiation stability of Tl signal against time, for the investigated material was predicted and discussed based on the calculated trap parameters. Since the principal trapping parameters (the activation energy and the frequency factor) are used for the evaluation of the stability of the Tl signal at a given temperature, thus the values of these parameters reveal the suitability of the studied materials to be used either in Tl dosimetry or dating of archaeological or geological samples. Implications about the possible results in glow curve deconvolution are discussed. (author)