Sublinear dose dependence of thermoluminescence and optically stimulated luminescence prior to the approach to saturation level

Analysis of alpha-alumina by variable dose and Tm -TSTOP methods and simulations of the whole process

The T_m -T_STOP and the variable dose methods were applied to alumina experimentally, and then all the steps of the methods were simulated numerically. The T_m -T_STOP experiments were performed between 70 and 300°C, and results showed that the glow curve of the used alumina had six distinct peaks between 40 and 400°C. The glow curves were analyzed using computerized glow curve fitting programs, the analytical equations were also fitted to the experimental data, and the trapping parameters of the peaks were measured. The samples were irradiated above the saturation level to ensure the complete filling of the electron traps and, therefore, the concentrations of traps were measured experimentally. Short-term anomalous fading behaviours of the peaks were investigated, and a new equation was proposed to compute the anomalous fading rate. In addition, the variable dose and T_m -T_STOP methods were simulated using the six trap-one recombination centre (6T1C) model and the experimental trapping parameters. Results showed that there was good harmony between numerical and experimental glow curves. After all the simulations were performed with acceptable accuracy, an estimate was made for the trapping coefficients (A_i = 1-6 ) that could not be measured directly from thermoluminescence experiments. Results showed that the trapping coefficients were affected by the applied dose.

Thermoluminescence characterization of Ag-doped Li2 B4 O7 single crystal materials

In this study, the thermoluminescence (TL) characteristics of Ag-doped and undoped lithium tetraborate (Li₂ B₄ O₇ , LTB) materials, grown using the Czochralski method, were reported. The TL properties of LTB:Ag, such as glow curve structure, dose response, fading and reproducibility, were investigated. The glow curve of the Li₂ B₄ O₇ :Ag single crystal consists of four peaks located at approximately 75, 130, 190 and 275°C; in undoped LTB, the single crystal shows a broad glow curve with peaks at 65, 90, 125, 160 and 190°C using a heating rate of 5°C/s in the 50-350°C temperature region. The high temperature peak of Ag-doped sample at 275°C has a nonlinear dose response within the range from 33 mGy to 9 Gy. There is a linear response in the range of 33-800 mGy; after which, a sublinear region appears up to 9 Gy for Ag-doped LTB single crystal. For undoped single crystal, the dose response is supralinear for low doses and linear for the region between 1 and 9 Gy. The thermal fading ratio of the undoped material is almost 60% for the high temperature peak after 7 days. Ag-doped LTB single crystal exhibits different behaviour over a period of 7 days.