Copper doped and strontium co-doped lithium magnesium borate glass as thermoluminescence dosimeter irradiated by co-60

Abstract

The present study has been conducted to investigate the thermoluminescence (TL) properties of copper (Cu)-doped and strontium (Sr) co-doped lithium magnesium borate (LMB) glass. Samples of undoped LMB, Cu-doped LMB, Cu-doped and Sr co-doped LMB were prepared using melt-quenching technique and irradiated with Co-60 gamma radiation at dose range of 1–100 Gy. X-Ray Diffraction (XRD) and Thermogravimetry-Differential Thermal Analysis (TG-DTA) showed all the samples are amorphous with good glass stability. All the samples were characterized using Thermoluminescence Dosimeter (TLD) reader and the TL properties were analyzed. In this study, it is found that the co-doped sample has better TL properties compared to the other samples and therefore was chosen for further analysis. The highest glow peak of the sample was observed at temperature of 190oC with the TL intensity of 4.14 × 105 nC g-1. The best annealing procedure of the sample was determined at 100oC for 20 minutes with the heating rate of 7oC s-1. The sample exhibits a good linearity with regression coefficient, R2 of 0.990 at low dose range of 1–10 Gy and R2 of 0.995 at high dose range of 10–100 Gy. The sensitivity of the sample is higher at 123 nC mg-1 Gy-1 in high dose range than that in a low dose range. The sample also shows low fading with the percentage signal loss of 48.2% at a low dose of 5 Gy and 47.7% at a high dose of 50 Gy after 60 days. The sample possesses good reproducibility with the percentage of standard deviation of 4% at 5 Gy and 6% at 50 Gy. Energy Dispersive X-Ray (EDX) analysis was used to calculate the effective atomic number (Zeff) of the sample which is 8.33 close to Zeff of human tissue. The minimum detectable dose of the sample is 2.44 mGy. In addition, the kinetic parameter analysis revealed that the type of glow curve of the sample is a second order kinetic. The activation energy of 1.2 eV and the frequency factor of 3.5 × 1011 s-1 were obtained using the initial rise method. Meanwhile, using the peak shape method, the calculated activation energy and frequency factor was 0.7 eV and 2.1 × 108 s-1, respectively. Thus, from this study, it can be concluded that the co-doped sample satisfies most of the desirable TL characteristics as a good material and could be used for thermoluminescence dosimetry application.