https://doi.org/10.1140/epjd/s10053-026-01123-0
Research - Atoms, Molecules, Ions, and Clusters
Excitation of metastable helium atoms by positron impact
1
NPAA, Research School of Physics, Australian National University, Canberra, Australia
2
Department of Physics, Indian Institute of Science Education and Research, 411008, Pune, India
3
Department of Physics and Astronomy, University of Nebraska, 68588-0288, Lincoln, NE, USA
a
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Received:
2
December
2025
Accepted:
19
January
2026
Published online:
12
February
2026
Abstract
We present measurements of the excitation of the 21S metastable state of helium by positron impact at energies between the threshold for excitation (20.6 eV) and 40 eV. The present results are obtained by directly measuring the yield of excited atoms that result from crossing a low-energy, high-resolution, magnetically confined and pulsed positron beam from a buffer gas trap with an effusive beam of He atoms. The measured excitation function is compared with previous measurements which used a scattering cell and with a recent state-of-the-art theoretical calculation.
© The Author(s) 2026
modified publication 2026
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