Electron capture by proton and alpha particle impact on helium atoms

The symmetric eikonal (SE) approximation, recently developed for K-K-shell electron capture in ion-atom collisions at intermediate and high energies, has been extended to charge exchange from 1s to low excited nlm states. Cross sections for capture into selective nl subshells (with n=1,2,3 and l=0,1,2) and into all possible bound states are calculated for the H + +He and He 2+ +He systems. Comparisons with experimental results and other theoretical approximations are shown.