Search

In this study an open-source tool GCD Analyzer, based on Microsoft® Excel, for Computerized Glow Curve Deconvolution analysis (CGCD) of thermoluminescence (TL) glow peak has been developed using a more accurate rational approximation. It is capable of deconvolution of glow curves having discrete or continuous trap distribution and can be used for routine as well as emergency radiation dosimetric analysis. This tool has a unique feature of TL glow curve analysis by combining discrete and continuous energy distributions for crystalline, amorphous, and mixed materials. To obtain best values of trap parameters like activation energy (E), frequency factor (s), order of kinetics (b), GCD Analyzer has the capability of analyzing glow curve using selectable individual peak of various physical kinetic models i.e. FOK, SOK, GOK, MOK, and Continuous Traps Distribution (CTD) with subtraction of optional background signal. The residual graph gives a clear visual understanding of the Figure of Merit (F.O.M). A comparison of asymptotic and rational approximation to the built-in second order exponential integral function E 2 (E/KT) for E/KT < 600 is also presented. The results are verified by deconvolution of test synthetic glow curves with F.O.M up to 0.0005%, experimental glow curve for CTD with F.O.M of 0.9781%, and in the case of GLOWCANIN project glow curves, the F.O.M is comparable to the least values achieved by inter-comparison participants. • Development of easy to use CGCD tool based on Microsoft Excel®. • Deconvolution of TL glow curves using individual or combination of various models. • An inter-comparison of asymptotic and rational approximations in TL expressions. • Accuracy of fitted results depends upon the selection of approximation. • Use of GLOWCANIN project and synthetic glow curves for validation and analysis. [ABSTRACT FROM AUTHOR]

A nano-sized, tissue equivalent, polycrystalline Li 2 B 4 O 7 :Cu, Ag phosphor was synthesized for dosimetric applications. Repeated annealing, irradiation and readouts may alter the color and affect the sensitivity of the phosphor. One of the aims of the present work was to dope Li 2 B 4 O 7 with an appropriate amount of Ag and Cu atoms in order to diminish such effects and consequently improve reproducibility and reusability of the dosimeter. For this purpose, Li 2 B 4 O 7 was primarily doped with Ag ions, and the Cu atoms were introduced with minimal concetration. A sample co-doped with 0.35 wt% Ag and 0.015 wt% Cu exhibited optimum TL response. To facilitate handling of the material, the powdered sample was also reproduced in pellet form. Linear integrated TL response was observed from 1 mGy to 20 Gy. No change in material's sensitivity and color was observed after repeated annealing, irradiation and readout episodes. Response of the material was found to be reproducible with a COV between 1.7 and 2.3%. Thermal quenching effects with increasing heating rate were seen for the current material. Less than 5% fading was observed during a two month study. The obtained glow curve was very simple having a main dosimetric peak at about 200 ± 10 °C with two small shoulder peaks. Kinetic analysis of the glow curve was performed by an experimental method (T m -T stop) and by curve fitting approximation. Kinetic parameters (b, s and E) were found within the prescribed limits. The promising dosimetric characteristics and the optimal glow curve favours this new material for use as a field dosimeter. • Polycrystalline (nano sized) Li 2 B 4 O 7 :Cu, Ag was synthesized via solid state sintering route for TL dosimetry. • A promising TL phosphor doped with optimal proportion of applied impurities (Ag = 0.35 wt%, Cu = 0.015 wt%). • The new dosimeter exhibited an ideal reproducibility (COV: 1.7–2.3%). [ABSTRACT FROM AUTHOR]

Thermoluminescence (TL), kinetic parameters and dosimetric features of Pakistani limestone (CaCO 3) is reported in this study. Both compositional and structural analyses reveal that the material has a crystalline nature with rhombohedral structure and non-uniform crystallite size having major content of CaCO 3. A powdered limestone sample of 30 mg is found to be the optimized weight for TL and other dosimetric studies. After irradiating the samples with a test dose of 100 Gy using a β source three composite glow peaks termed as P1, P2 and P3 are visible at 100, 230 and 330 °C respectively using a linear heating rate of 1 °C/s during the TL readout. The Coefficient of Variation (COV) is found to be about 4%. Kinetic parameters (i.e., frequency factor (f), activation energy (E), and the kinetic order (b)) are estimated using both first and second Order of kinetics using an in-house Computerized Glow Curve Deconvolution (GCD) software. The figure-of-merit (FOM) is found to be 2.12%. The distribution of continuum traps with activation energy in the range of 0.77–2.59 eV is observed in the kinetic parameter analysis of the glow peaks of the sample. The TL response in the dose range of 1–5 Gy (not reported previously) and linearity in the dose response in the dose range of 1–10 Gy is observed in samples of Pakistani limestone. The Minimum Detectable Dose (MDD) is 1.01 Gy clearly resembling the experimentally linear fitted results. After a fading study for a period of thirty days, only the first peak i.e., P1 majorly fades while no major change is observed in the amplitude of peaks P2 and P3. In addition, P1 is the main contributor fading by 92% within the first 24 h of irradiation while P2 fades by 30 %. However, P3 shows stability with a very minor fading of 0.05% within 24 h of irradiation. This study concludes that Pakistani limestone can be further assessed as a potential radiation dosimeter for various applications. • Material characterization, TL, kinetic parametric analysis and other dosimetric features of Pakistani limestone were investigated. • Sample weight optimization study was performed for powdered Pakistani limestone. • Three glow peaks P1, P2 and P3 were observed with a test dose of 100 Gy with beta source while fourth peaks was identified using deconvolution by CGCD method. • TL response observed between 1–5 Gy with Minimum Detectable Dose (MDD) of 1 Gy and 3.4 % Coefficient of Variation (COV). [ABSTRACT FROM AUTHOR]