The bleaching effect of positron irradiation of KCl and KBr single crystals previously colored with electrons or protons was investigated. Positrons injection in the colored alkali halide samples reduces the F-centers concentration considerably. For KCl crystals thicker than the positrons range the appearance of additional bands in the absorption spectra is noticeable. The experimental data show that the bleaching phenomenon should be observed merely throughout the positron exposure both for irradiated and nonirradiated regions of the sample. Irradiation effects, due to positron source, on the peak counting rate of ( gamma - gamma ) angular correlation in KCl crystals under applied magnetic field were also investigated. The growth of peak counting rate shows the increase of positronium-like states formation near defects of cation sublattice.
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