Application of commercial glasses for high gamma dose measurement using optical densitometric technique

Commercial glass plates have been studied for their optical density (OD) changes following 60Co gamma radiation exposure in the dose range 0.10-100kGy. These glasses have responded linearly upto 15kGy gamma doses; thereafter, the OD response became slower and reached to saturation level at 80kGy. No further increments in the optical densities of the glasses have been observed beyond 80kGy gamma doses. In general the glasses are found suitable for gamma radiation measurement in the dose range 0.10-40kGy using optical densitometric technique. Glasses have shown OD signal fading in the range of 5.0-14.0% in first 24 h after exposure under laboratory conditions. However, the fading contributions due to various environmental conditions such as; dark and 25∘C; fluorescent room light and 25, 50, 70∘C; solar light and 35∘C in first 5 h after radiation exposure have been observed as 0-5%, 0-6%, 11-32%, 31-65% and 54-68%, respectively. Optical densitometry technique using glass plates reveal reproducible dosimetric results within ± 15%. Some elements present in the glasses (K, Na, Mg, Zn and Fe) have been observed as the main contributors in the formation of colour centres in glass lattice, which change the absorption spectra of visible light. The glass with higher percentage of these elements has shown higher OD sensitivity after gamma exposure. Commercial glass plates can be used as radiation dosimeter for radiation processing facilities. It can also be used for quality assurance and absorbed dose estimation in irradiated samples for any high radiation dose facilities. The irradiated glass samples must be protected from ambient and solar light exposure during or after irradiation and should be stored in cool environment to minimize the losses of stored optical densitometric informations.