Excitation of Swift Heavy Ions in Foil Targets. V Production of Rydberg States

Abstract

The results are summarised of previous experiments on the beam-foil excitation of Rydberg states of Br ions containing L vacancies. These show two populations, namely one with high angular momentum .e leading to 'yrast' cascades, and a separate low-.e population. Models for the production of such states in solid targets are discussed, and experiments to test the predictions of these models are described. The target-thickness dependence and downstream decay of the 'yrast' states is consistent with a standard charge-changing and capture model. The low-.e population is very sensitive to the presence of an applied electric field, and it is concluded that such Rydberg states are partly created by the radiative recapture of free 'convoy' electrons which travel physically near their host ions. Detailed level and decay schemes are described for the Br2S+, Ne-like system.