Weak hyperfine interaction of E ' centers in gamma and beta irradiated silica

We report on the effects of photon (gamma) and electron (beta) irradiation in a dose range extending from 100 to 5 x 10(9) Gy in a variety of silica s amples studied by electron paramagnetic resonance. The E-' centers and a we ak intensity satellite signal of their resonance line were generated both i n gamma- and in beta -irradiated samples. We investigated the dependence of their intensity on the irradiation dose. Evidence of the existence of a co mmon generation mechanism for the related paramagnetic point defects is fou nd. These defects are induced mainly through the conversion of precursors e xcept at very high doses, where the direct activation from the unperturbed matrix is concurrent. Our data support the model attributing the satellite signal to the weak hyperfine structure of the E' center arising from intera ction with a second nearest neighbor nuclear spin. (C) 2001 American Instit ute of Physics.