Study of the electron-positron annihilation coincidence peak two-dimensional profile

Abstract

Positron annihilation radiation profile in aluminum was observed with a pair of Ge detectors in coincidence. 22Na was used as a source of positron and the two-dimensional gamma energy spectrum was fitted using a model function. Annihilation components of positron at rest with conduction band, 1s, 2s, and 2p electrons were observed. The in-flight positron annihilation was also observed. The model function also took into account the detector response function, relative efficiency corrections and the gamma backscattering. Coincidences involving a combination of Compton effect, pileup, ballistic deficit, and pulse shaping problems were treated as well.