Band Structure and Positron Annihilation in Metals: Be and Mg

Abstract

The angular correlation of positron annihilation radiation from oriented beryllium and magnesium crystals has been measured. The derivatives of the angular distributions from beryllium show fine structure and marked anisotropy compared to the observed nearly isotropic behavior of magnesium. A qualitative theoretical interpretation of the data is given in terms of the Bloch functions of the conduction band. It is emphasized that the correlation curves are sensitive to the details of these wave functions and do not yield directly cross-sectional areas of the Fermi distribution.