Excitation and ionization of excited helium atoms in collisions with bare ions

A comparative study has been made on the cross sections for excitation of He(n=2-->2-5) and He(n=3-->3-5) and for ionization of the He n(1,3)S and n(1,3)P states with n=2-5 in collisions with H+, Be4+ and B5+ in the Glauber and the continuum distorted wave-eikonal initial state approximations, respectively, besides the Born approximation. A comparison is made between the present results and other theoretical predictions.