Electron Interaction and Positron Annihilation in Electron Gases

An intuitive many- body treatment is presented of the distribution in the total momentum of two gamma rays emitted in annihilation of positrons in a gas of interacting electrons. This treatment results in a momentum distribution of photon pairs which is very close to that of the ideal Fermi distribution of quasi-electrons in the electron gas. This seems to be supported by Stewart's experiment for sodium metal