Effect of reader and oven annealing on the glow curve structure and fading of a LiF:Mg,Cu,P TL dosimeter.

The effect of pre-irradiation annealing in an oven at 240 degrees C/10 min (oven anneal) and in a TLD reader at 6 degrees C s(-1), 10 s dwell time at a maximum temperature 240 degrees C (reader anneal), on the glow curve structure of a home made sample of LiF:Mg,Cu,P powder has been investigated. It is shown that on oven annealing the glow peak areas of peaks 2 and 3 increase and that of peak 4 decreases, while on reader annealing the area of peak 4 increases and those of peaks 2 and 3 effectively decrease. Values of fading during a post-irradiation storage of 6 months were measured to be 26% and 12% for samples undergoing oven and reader annealing respectively. To reduce the effect of fading several pre-heats at temperatures of 100, 110, 120 and 130 degrees C for 10 min were investigated and 120 degrees C/10 min was chosen as the optimal condition for pre-heat. It is also observed that when imposing pre-heat thermal treatment on this dosimeter or storing the irradiated dosimeter the height of peak 4 effectively increases while the integral of TL signals remains constant.