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 S e obtained are compared with theory. The previously reported periodic dependence of S e in solids on the atomic number Z 1 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 Z 1 values are discussed.