Energy loss of Ni ions transmitted through C foils at MeV energies: A charge state approach

The stopping power of MeV ions transmitted through carbon foils is dominated by target electron excitations. However, it is necessary to take into account the fact that several charge states may contribute to the total energy loss. We use a charge state approach to calculate the electronic energy loss to the valence electrons of carbon by Ni ions at MeV/A energies using a dielectric description of the target valence electron excitations and a simple model to describe the projectile ion charge states. Comparison with experiments and with Brandt-Kitagawa effective charge theory is made. The effect of the excitation state of the projectile electrons is also considered, as well as an order of magnitude estimate of the Barkas correction, the energy loss in charge changing processes and the contribution from the target K-shell electrons.