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arXiv · 1706.04948

Probing positron cooling in noble gases via annihilation $γ$ spectra

D. G. Green
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Abstract

$γ$ 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 $γ$ spectra produced during positron cooling in noble gases. The $γ$-spectra and their $\bar{S}$ and $\bar{W}$ 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.

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D. G. Green. 2017-06-29. Probing positron cooling in noble gases via annihilation $γ$ spectra. https://doi.org/10.1103/physrevlett.119.203404

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