Gamma Irradiation of Lead Silicate Glass

Abstract

GLASSES exposed to gamma radiation darken due to the trapping of electrons in defects. Much work has been done by Seitz and others on colour centres produced in alkali halides by irradiation. Glass has also been studied by many workers, and it is well known that the intensity of the colour produced in glass fades in the dark and that this process is accelerated by increase in temperature or by exposing the glass to light. The present work was undertaken to investigate the mechanism involved in the darkening of glass, and the recovery in the dark with time, in an attempt to obtain better understanding of the structure of glass. A lead silicate glass of weight percentage composition PbO–80, SiO₂–20 was chosen because of the simplicity of its chemical composition (approximately PbO.SiO₂). Such glass might be expected to provide a simple absorption spectrum after irradiation. Rectangular blocks of glass 1 cm. × 1 cm. × 3 cm. cut from a single block of glass had their 1 cm. × 3 cm. faces ground and polished to be flat and parallel.