Impact parameter dependence of electronic energy loss and straggling in fast proton-atom collisions

The impact parameter dependence of the electronic mean energy loss and energy loss straggling is calculated for fast proton collisions with noble gas atoms. The independent electron model using the Hartree-Slater potential is used for the description of the atoms. A summation over all final atomic states is made explicitly. Results of calculations for Ne, Ar, Kr and Xe atoms are presented and compared with recent experimental data by Auth and Winter. Good agreement with experiment is observed for the impact parameters b < 1.2 a.u., whereas for larger impact parameters the calculations underestimate the experimental data.