ENERGY OF FORMATION OF RADIATION DEFECTS IN CaF//2 .

An investigation was made of the relaxation of the absorption spectra of pure and doped CaF//2 crystals after irradiation with a nanosecond pulse of 200 keV electrons at temperatures from 100 to 520 degree K. At sufficiently high temperatures the F-band absorption, measured immediately after the end of an electron pulse, predominated over the absorption by self-localized excitons. Photochromic color centers were generated in yttrium-doped crystals during an electron pulse. The primary products of decay of the electron excitations were found to be F-H pairs. The energy of formation E//0 of a primary pair of radiation defects was deduced from a study of the kinetics of radiation-stimulated conversion of the M//A into F//A centers and the kinetics of accumulation of the photochromic color centers. It was found that the formation of one primary pair of defects in a CaF//2 crystal required no more than 100 eV of the absorbed radiation energy.