Positron trapping at H- and D- ions in MgO crystals

Low-temperature positron lifetime and Doppler-broadening measurements Stave been performed on MgO single crystals containing either H- or D-. The temperature dependence of the mean positron lifetime and the parameter S indicate that the positron trapping coefficient for H-(D-) ions increases with temperature. A model involving delocalized, self-trapped, and bound states [e(+)-H-] and [e(+)-D-] for positrons predicts the temperature dependence observed for the annihilation parameters.