A 2D dosimeter based on glass for gamma irradiation

Abstract

The aim of this thesis was to develop a 2D dosimeter based on glass. Porous VYCOR® 7930 silicate glass doped with fluorescent quantum dots (QDs), CdSe/ZnS was investigated. Initial studies were made of the radiation resistance of a soda-lime glass microscope slide. The PENELOPE Monte Carlo was used to understand the deposition of radiation in the materials under consideration. In this work, the study of the radiation resistance behaviour was made in term of changes to the optical absorbance. The microscope slide was irradiated with 60Co gamma rays and damage at optical absorption bands of 400 – 440 nm and 600 – 620 nm was observed. The long-term annealing of this glass in the dark was measured over a period of 175 days. The effect of changing the dose rate was measured. New measurements of the radiation tolerance of Corning VYCOR® 7930 nano-porous glass showed low radiation damage at any region of the visible spectrum at doses up to 900 Gy. It is thus a stable substrate for hosting a material with significant change in properties with radiation. In an optical experiment, VYCOR® 7930 with a doping of fluorescent CdSe/ZnS core-shell quantum dots (QDs) which are easily damaged by radiation doses of order 10 Gy demonstrates the possibility as a readout dosimeter by measuring the visible fluorescence. The QDs fluorescence was stable under near UV excitation for a period of at least 6 hours.