Radiation effects in hydrogen‐impregnated vitreous silica

γ irradiation of vitreous silica normally leads to the formation of a large number of optical defects and to an increase in density. Irradiation of hydrogen‐impregnated vitreous silica suppresses the formation of these optical defects, but does result in the formation of large quantities of bound hydroxyl and hydride. This process is accompanied by the expansion (density decrease) of the glass. The rates of hydroxyl and hydride formation and the density decrease all are proportional to the square root of the applied dose. The mechanism responsible for these results is not clear at this time.