The effect of gamma-irradiation on the density of various types of silica

The radiation-induced changes in density of 11 different silicas, both natural and synthetic, exposed to gamma-irradiation from 10 4–10 9 rad were measured using a linear density gradient column. It was determined that, in general, the ‘dry’ silicas that contain less than 150 ppm OH compact monotonically with dose; however, the silicas containing more than 150 ppm OH tend to expand initially and then compact at higher doses.