Thermoluminescence characteristics of LiF:Mg,Cu,P + PTFE irradiated with beta particles

Among the various thermoluminescent (TL) phosphors developed in our laboratories, the tissue equivalent, high sensitive and very stable LiF:Mg,Cu,P TL material has turned out to be of special interest to be used in environmental monitoring and medical dosimetry. Dosimetric characteristics of this material, in powder form, have been reported in previous works. In order to have this material in solid form we developed a method to prepare pellets of this phosphor embedded in polytetrafluoroethylene (LiF:Mg,Cu,P + PTFE). This paper presents the results of studying the thermoluminescent response and the kinetics of these LiF:Mg,Cu,P + PTFE pellets when irradiating them with 90Sr/90Y beta particles. The results showed that LiF:Mg,Cu,P + PTFE exhibits a typical glow curve with three peaks at 120, 210 and 285 deg C, respectively, which were separated by the deconvolution method. Applying this method, we obtained that all of them obey a first order kinetics and have an activation energy of 1.35, 1.58 and 2.51 eV respectively. The TL response as a function of dose was linear in the range from 4.35 mGy to 2.17 Gy, which became supralinear up to 21.75 Gy. This response saturates from 43.5 Gy. All the results were compared with those obtained for TLD-100 chips submitted to the same irradiation conditions. (author)