Thermoluminescent properties and kinetics parameters of MgO:Sm,Tb+PTFE dosimeters.

This work reports on the TL response of magnesium oxide co-doped with Sm and Tb (MgO:Sm,Tb), synthesized through the solution combustion method. To characterize the structural and compositional properties of the prepared material, XRD and SEM techniques were employed. Some of the obtained powders were prepared in pellet form using Polytetrafluoroethylene (PTFE) as binder (MgO:Sm,Tb + PTFE). After some trials, it was found that the MgO:Sm,Tb + PTFE with 0.4 and 0.1 mol% of Sm and Tb, respectively, showed the best TL results. The thermoluminescent response was investigated under gamma and UV radiation. For gamma irradiation the results indicate that the sensitivity of these new dosimeters showed an increase of 2.3 times with respect to the sensitivity shown by the material without binder. The lower detection limit (LDL) of these new dosimeters was 0.06 mGy, with a coefficient of variability (CV) of 0.69%. No fading was found in the first 3 days while the TL signal fades approximately 26% after 30 days. The Sequential Quadratic Programming Glow Curve Deconvolution (SQPGCD) method was applied to the glow curves to determine their kinetic parameters revealing two peaks of general-order kinetics. Concerning the TL response of MgO:Sm,Tb + PTFE under UV radiation (λ = 254 nm) a single glow curve centered at 452 K was found and the TL signal as a function of the dose showed a non-linear behavior approaching saturation for doses higher than 433.8 mJ/cm2. These new dosimeters could be promising in dosimetry applications.