Excitation of Metastable Helium Atoms by Positron Impact

ORAL

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.

*Support: Australian Research Council (ARC) Discovery Grant DP200101294; US NSF Grant PHY-2437820 (TJG); ARC Research Council Future Fellowship Grant No. FT220100670SSH (SSH); ARC Future Research Talent Award (SK).

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Publication: Excitation of Metastable Helium Atoms by Positron Impact
Liam Wymer, S. Kumar, T. J. Gay, Sean S. Hodgman, Stephen J. Buckman and Joshua R. Machacek
accepted for publication in the European Physical Journal D

Presenters

  • Timothy J. Gay

    • University of Nebraska - Lincoln

Authors

  • Timothy J. Gay

    • University of Nebraska - Lincoln

  • Liam Wymer

    • Research School of Physics, Australian National University, Canberra, Australia

  • Sharan Kumar

    • Department of Physics, Indian Institute of Science Education and Research, Pune, 411008, India

  • Sean S Hodgman

    • NPAA, Research School of Physics, Australian National University, Canberra, Australia

  • Steven J Buckman

    • NPAA, Research School of Physics, Australian National University, Canberra, Australia

  • Joshua R Machacek

    • NPAA, Research School of Physics, Australian National University, Canberra, Australia
    • Australian Natl University