Structure in the energy dependence of high-energy electron-capture cross sections

Abstract
Previous experimental and theoretical work has found electron capture to be a monotonically decreasing function of energy in fast ion-atom collisions. We report here the experimental observation of nonmonotonic behavior of the electron-capture cross sections in fast collisions of calcium ions, in charge states 16+ to 19+, with molecular hydrogen, in the energy range 97368 MeV. The structure observed in the measured cross sections is attributed to the contribution of resonant transfer and excitation to electron capture.