The optical absorption spectra of nominally pure or rare-earth ion-doped (Ho3+ or Er3+) glasses were measured before and after γ-irradiation. The induced absorption spectra (defined as the difference between the spectra of irradiated and unirradiated glasses) exhibited characteristic absorption bands which were produced by the respective rare-earth ion. The intensity of the induced bands depended upon the rare-earth oxide content. The response of the glass to irradiation was related to the formation of color centers

which were associated with intrinsic defects in the lattice structure of the glass. The rates of formation and annihilation of the color centers were suggested to approach saturation or equilibrium during prolonged irradiation.

Interaction of Gamma Rays with Calcium Aluminoborate Glasses Containing Holmium or Erbium. H.A.El-Batal, M.A.Azooz, F.M.Ezz-El-Din, N.A.El-Alaily: Journal of the American Ceramic Society, 2001, 84[9], 2065-72