Coupling between positron-atom scattering channels above the first inelastic threshold.
Experimentally determined cross sections for the elastic scattering of positrons by argon and xenon atoms have been found to exhibit a steplike increase at the first inelastic threshold energy--i.e., that for positronium formation. Rather than supporting the existence of a cusplike behavior predicted theoretically, this feature, which is more pronounced for xenon, suggests the existence of an intermediate virtual positronium state which enhances the elastic interaction probability.
Coleman
P G
PG
Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom.
Cheesman
N
N
Lowry
E R
ER