DISCUSSION ABOUT THE EFFECTS OF CRYSTAL LATTICE ON POSITRON ANNIHILATION

In this paper, we use Green's function method to study the first-order ladder graphs which include lattice-electron and lattice-positron interaction lines. We calculate some low order Feynman graphs in taking the static limit for electron-positron effective interaction potential, and obtain the formula of partial annihilation rate of the positron for ppF. Furthermore, we make some numerical calculations, and discuss and compare them with the results of Hede-Oarbotte's theory.