Nature of the centres of positron annihilation in intensively irradiated alkali halides

The positron capture centres are identified in high irradiated (in the temperature range of 300 to 520 K) KBr. The dependences of the intensity of the annihilated 2γ radiation on the temperature of proton irradiation and that of a following pulse heating of crystals are studied. The spectra of optical absorption of the crystals are measured under identical conditions. The volume rates of a positron capture into the basic radiative defects are calculated. The divacancies are shown to be the basic centres of positron capture in the investigated temperature range in the high irradiated alkali halides. (author)