Positron Annihilation in Metals

An adequate description of positron annihilation rates in metals is obtained by extension of the high-density limit, for annihilation in an electron gas, to realistic densities. A short-range electron-positron force is obtained in the high-density limit and is used to treat accurately the two-body correlations between the positron and metallic valence electrons. This description proves to be satisfactory for metals with low valence electron densities as well. The variation of annihilation rates with valence electron density, and also the absolute rates, agree quite well with those obtained experimentally by Bell and Jrgensen.