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

Abstract

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.

Review of the thermoluminescent dosimetry method for the environmental dose monitoring

“…The peak four has been shown to have a high ther mal sta bil ity and fades in de pend ently of the tem per a ture whereas the low tem per a ture peaks de cay ex po nen tially and are strongly de pend ent on tem per ature [43]. The to tal TL out put has been re ported to post-ir ra di a tion fade up to 26 % [46]. The peak area ratios in volv ing lower tem per a ture peaks were found to de crease more quickly than those in volv ing higher tem per a ture peaks.…”

“…Sev eral well-con ducted stud ies [43][44][45][46] have inves ti gated the pre-ir ra di a tion and post-ir ra di a tion fading rates of LiF:Cu,Mg,P. These stud ies have re ported the ex po nen tial de cay of third glow curve peak both be fore and af ter an ir ra di a tion and an in crease in the total area of fourth peak dur ing pre-and post-ir ra di a tion fad ing [43,45].…”