Calculations of the energy loss of ⁴He ions in solid elements

We have calculated the energy loss of 4He ions in a number of elemental and rare-gas solids in the energy range from 0.4 to 4.0 MeV. The calculations are based on the Lindhard-Winther energy-loss formalism and use solid-state charge densities for the target atoms. Stopping cross sections εα are presented as a function of projectile energy and are compared with the Hartreee-Fock-Slater isolated-atom calculations and semiempirical cross sections. It is found that the solid-state charge densities generally produce a somewhat better energy dependence than the atomic charge densities but that neither produces an adequate fit in the low-energy region. In particular, solid-state effects of Ne and Ar lead to a 4-10% increase over the atomic calculations.