We report the first direct observation of a resonancelike structure for positron scattering by an atom or molecule. Our initial absolute elastic differential cross-section measurements for positron scattering by argon when plotted versus energy (8.7 to 300 eV) at fixed scattering angles of 60^∘{}, 90^∘{}, and 120^∘{} reveal an unexpected drop (a factor of 2 at 60^∘{}) between 55 and 60 eV. This structure is puzzling because it does not occur near any known inelastic threshold energy and may relate to a cross-channel coupling effect with an open inelastic-scattering channel.
No takes yet. Share an insight, caveat, or question.
Dou et al. (1992) studied this question.