Abstract
This article contains detailed evaluation of thermal, mechanical, radiation shielding and thermoluminescence (TL) properties of heavy metal oxide (HMO) borosilicate glasses having composition xBi2O3- (60-x) B2O3- 20SiO2- 12ZnO- 8BaO (with x= 0, 2, 4, 6, 8, 10 and 12 mol%). Gamma shielding capacity of these glasses was examined in terms of mass attenuation coefficient (MAC) values, exposure and energy absorption build- up factor (EBF/EABF). The experimental MAC values were found to agree well with the theoretical results obtained from Photon Shielding and Dosimetry (PSD/Phy-X) software. Geometric Progression fitting method was used for the calculation of build- up factors in the photon energy region of 0.015-15 MeV with the help of five parameters (a, b, c, d and Xk). The pattern followed by build-up factors with the gamma energy and their variation for different penetration depths up to 40 mfp was observed and analysed. High values of equivalent atomic number and build up factors for high bismuth sample (12 mol%) gave evidence for its improved radiation shielding capacity. Furthermore, thermoluminescence study was done to assess the suitability of the synthesized glasses as a radiation dosimeter in the gamma dose range of 0.25 – 30 kGy. Here, 5 kGy irradiation exhibited major quenching in TL signal on adding bismuth to the glass network. TL performance of ZBiB-8 was noteworthy with charges trapped in high temperature trap centres with longer lifetime. TL dose response curve of ZBiB-8 showed good linearity in the dose range of 0.25 – 5 kGy. Fading analysis was done for this sample to find the loss in TL intensity in the course of one month. Heating the ZBiB-8 sample to 323 K (50 0C) for 15 min was found to be a proper annealing condition for re-using it as a thermoluminescence dosimeter (TLD).