Elastic differential cross sections for small-angle scattering of 25-, 50-, and 100-keV protons by helium atoms

Abstract

The first measurements of elastic differential cross sections have been carried out for 25-, 50-, and 100-keV protons scattered through very small angles by helium atoms. The University of Missouri\char22{}Rolla energy-loss spectrometer provided the required high angular resolution and also separated the elastically scattered ions from the inelastically scattered ions. The data are compared to our Born, Glauber, and classical calculations as well as a four-state calculation. All of the measured elastic differential cross sections are more sharply peaked than theory for the smallest scattering angles. At the larger scattering angles all of the measured elastic differential cross sections are below the theoretical calculations. However, if the classical calculation is interpreted as a total differential scattering cross section, it compares well with our estimate of the sum of the elastic, charge-transfer, and inelastic differential cross sections.