Binary-encounter stopping cross sections. II. Calculations for helium in multielectron atoms, target Z dependence

A previously developed model which describes the slowing down of energetic heavy charged particles in matter due to electronic collisions is generalized to multielectron target atoms. The model utilizes the binary-encounter approximation to describe the slowing-down collisions and explicitly takes into account the equilibrium charge-state composition of the incident ion beam. Extensive calculations of the electronic stopping cross sections of atomic targets from hydrogen to krypton for incident helium are made using the model, and the results are presented as a function of incident energy between 0.1 and 10 MeV for selected targets and as a function of target atomic number for various incident energies. Agreement with experiment is fairly good for light target elements, but the calculated results seriously overestimate measured cross sections for the heavy transition elements at large energies. Possible explanations of this discrepancy are discussed and comparisons are made with various other theories.