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Published on: July 12, 2016
Near-Threshold Ionization of Argon by Positron Impact
T J Babij1, J R Machacek1, D J Murtagh1
1Plasma Research Laboratory, Research School of Physics and Engineering, Australian National University, Canberra ACT 2601, Australia.
Abstract:
The direct single-ionization cross section for Ar by positron impact has been measured in the region above the first ionization threshold. These measurements are compared to semiclassical calculations which give rise to a power law variation of the cross section in the threshold region. The experimental results appear to be in disagreement with extensions to the Wannier theory applied to positron impact ionization, with a smaller exponent than that calculated by most previous works. In fact, in this work, we see no difference in threshold behavior between the positron and electron cases. Possible reasons for this discrepancy are discussed.
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