effect of cobalt-60 radiation on thermoluminescence properties of copper doped and terbium doped sodium magnesium borate

Abstract

This thesis presents the investigation of thermoluminescence (TL) properties of copper (Cu) doped and terbium (Tb) doped sodium magnesium borate (NaMgBO3) as a thermoluminescence dosimeter (TLD) material. Undoped NaMgBO3 and two doped samples with various concentrations of dopant Cu (0.1- 0.5 mol%) and Tb (0.02- 0.1 mol%) were successfully prepared by combustion synthesis method. The effect of two different dopants and their concentrations was studied for TL properties subjected to Cobalt-60 gamma irradiation. The structure of the undoped sample was studied using X-ray diffraction and showed the presence of polycrystal structure with average size of 32 nm. The doped samples exhibit simple glow curve with single peak that occurs around 175 oC and 280 oC for Tb doped and Cu doped sample respectively. The undoped sample exhibits double peak glow curve with peaks located around 175 oC and 300 oC. Sample doped with 0.07 mol% Tb shows the highest TL response with activation energy of 1.00 eV. It also exhibits the highest TL response sensitivity which is 222 times compared to that of the undoped sample. Furthermore, it also gives the lowest fading effect with 5% signal loss over 28 days. Tb doped sample also shows good reproducibility with slightly different TL response reading within the range of ( 1.3 – 1.4 ) × 108 nC/g over 6 times readout. All samples show good linearity with linear correlation coefficient of 0.99518 for undoped sample, 0.99713 for Cu doped sample and 0.99518 for Tb doped sample. In conclusion, NaMgBO3 : 0.07 mol% Tb exhibits the best TL properties among the other samples and has the potential to become a new TLD material for radiotherapy and radiation processing.