Stopping cross section in atmospheric air of 0.2–0.5 MeV atoms with

Abstract

The stopping cross section S = dE/NdR in atmospheric air has been measured for ions with [Formula: see text] and the energy ranging from 0.2 to 0.5 MeV. The experimental data have been corrected numerically for nuclear stopping, and the electronic stopping cross sections Se obtained are compared with theory. The previously reported periodic dependence of Se in solids on the atomic number Z1 of the incoming ion for constant velocity is also seen in the present data for a gas target. The structure of the oscillations is found to be insensitive to whether the target is a solid or a gas. In the last part of the paper, some preliminary measurements of the charge-state distributions of the ions emerging from the gas target for various Z1 values are discussed.