Double excitation of He and H{sup {minus}} by fast proton and anti-proton impact

Abstract

Theoretical investigation has been made on double excitation processes of He and H{sup {minus}} by fast proton and anti-proton impact in the MeV/u-energy region. The cross sections are calculated by use of both the close-coupling and the perturbation expansion methods, and the wave functions of target atoms are generated based on the hyperspherical coordinate method. The excitation to the 2p{sup 2} {sup 1}D{sup e} state of H{sup {minus}} by anti-proton impact is dominant by about three times in comparison with that by proton impact at the incident energy of 0.1 MeV/u. The spectral shape of an ejected electron from the 2s2p {sup 1}p{sup o} state of H{sup {minus}} at the incident energy of 1.5 MeV/u is consistent with the line profile of the H{sup {minus}} photodetachment observed by Bryant et al.