A comparison of the theoretical and experimental results for keV electron scattering from argon

Experiments studying the scattering of keV electrons from noble gas atoms have been performed in the past, as the first Born approximation (FBA) was thought to be valid under these conditions, and hence it was expected that these experiments could be modelled relatively straightforwardly by theory. Somewhat surprisingly these experiments have so far attracted only very limited theoretical interest and the ability of modern scattering theory to describe them has not been firmly established. In our earlier study of the cross section for the resonant transitions, we established that the FBA was sufficient to describe the results for small scattering angles, but it did not account for the observed intensity at larger angles. Here we extend this comparison for the case of argon to monopole, quadrupole and octopole transitions below the continuum. The experimental results show differential cross sections spanning many orders of magnitude for these transitions. The relativistic distorted wave theory developed here describes these experiments for many transitions and a large range of scattering angles reasonably well. (paper)