research

Probing positron cooling in noble gases via annihilation γ\gamma spectra

Abstract

γ\gamma spectra for positron annihilation in noble-gas atoms are calculated using many-body theory for positron momenta up to the positronium-formation threshold. This data is used, together with time-evolving positron-momentum distributions determined in [arXiv:1706.01434 (2017)], to calculate the time-varying γ\gamma spectra produced during positron cooling in noble gases. The γ\gamma-spectra and their Sˉ\bar{S} and Wˉ\bar{W} shape parameters are shown to be sensitive probes of the time evolution of the positron momentum distribution, and thus provide a means of studying positron cooling that is complementary to positron lifetime spectroscopy.Comment: This version contains minor update to references, otherwise unchange

    Similar works