We. Kauppila et al., EVIDENCE FOR RESONANCE AND ABSORPTION EFFECTS IN POSITRON-ATOM DIFFERENTIAL ELASTIC-SCATTERING, Hyperfine interactions, 89(1-4), 1994, pp. 143-160
This review focuses on recent positron-atom elastic differential cross
section (DCS) measurements which reveal evidence that interference ef
fects may be occurring between the elastic and inelastic scattering ch
annels. These effects appear as (1) absorption effects which are obser
vable in relative elastic DCSs by the ''washing out'' of structure in
the DCS versus angle as the positron energy is increased above the pos
itronium formation threshold, and (2) a new type of resonance-like str
uctures at intermediate energies (well above the normal inelastic thre
sholds) that have been observed in absolute elastic DCS measurements w
hen plotted at a fixed scattering angle versus energy. A discussion is
provided of possibly relevant information on positron-atom scattering
that also indicates that coupling is occurring between various scatte
ring channels.