The Three-Photon Annihilation of Positrons and Electrons

Abstract

The physical characteristics of the radiations emitted in the annihilation of positrons and electrons in the triplet state have been studied with a triple coincidence method. The energies of the three gamma rays, the angular distribution, and their polarization were found to agree with theory. Triplet annihilation was studied both from positrons stopping in gases where positronium was formed, and from positrons stopping in condensed materials. In the case of metallic absorbers, we verified within the accuracy of the experiment that the number of triplet annihilations is 1/370 of the number of singlet events. Experiments on the number of three-quantum annihilations in different materials are described.