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

Abstract

Positron annihilation radiation profi le in aluminum was observed with a pair of Ge detectors in coincidence. 22 Na was used as a source of positron and the two-dimensional gamma energy spectrum was fi tted 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 effi ciency corrections and the gamma backscattering. Coincidences involving a combination of Compton effect, pileup, ballistic defi cit, and pulse shaping problems were treated as well.

Study of the Doppler broadening of positron annihilation radiation in silicon

“…Usually, the results of Doppler broadening experiments have been analyzed through the comparison of the calculated annihilation probability density with the experimental data. In this work we went in the inverse direction: a model function was fitted to the experimental data in order to obtain the distribution of electron momenta, similar to the analysis accomplished for the aluminum [3,4]. In these works the coincidence energy spectrum was fitted using a model function, accounting for both Doppler broadening and detector system response.…”