Stopping power of solid argon for helium ions

By means of the Rutherford-backscattering method, the stopping cross section of solid argon has been measured for 0.5-3 MeV helium ions to an accuracy of approx. equal to 3%. The results agree within the experimental accuracies with our earlier measurements for gaseous argon over the energy region studied. This proves that the gas/solid difference for argon predicted in recent stopping-power tabulations is significantly overestimated. With high-order Z1 correction terms included in the theoretical description, calculated shell corrections based on the Lindhard-Scharff model are in good agreement with the experimental results even down to energies close to 0.6 MeV. (orig.)