Reference stopping cross sections for hydrogen and helium ions in selected elements

Abstract

This article presents new fits to all the available published experimental data on electronic stopping for hydrogen projectiles (10 to 2500 keV/nucleon) on Au, Ag, Cu, Ni, and Al, and for helium projectiles (60 to 7500 keV) on Au and Ag. In all of these cases, we also have data measured in our own group. The data from 13 (Out of 123) publications are rejected a priori, mostly because the measurements are relative. We use a least-squares fit to a four-parameter function of the energy, and we reject discrepant data using two statistical criteria. Our fit results are shown graphically together with all the data points and with various fits by other authors. For hydrogen projectiles, we find that the stopping maximum has a lower value than given by Andersen and Ziegler, except in the case of Al, where almost all the fits agree well. For helium projectiles, the agreement of the various data sets and of the fits is generally better. For both types of projectiles, the fitted cross sections for Ag and Au do not cross in the energy region considered, which is not true of fits by other authors.