Backscattering of light atomic projectiles from thin Au films in the energy range 50–110 keV

Authors:
  • AWA. van Wijngaarden
    A. van Wijngaarden
  • EBE. J. Brimner
    E. J. Brimner
  • WBW. E. Baylis
    W. E. Baylis
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Abstract
Thin gold films, vacuum deposited onto a beryllium substrate, have been irradiated by projectiles of 1H, 4He, 7Li, and 11B in the energy range 50–110 keV and the backscatter intensity measured at a laboratory scattering angle of 136.4°. An analytic expression for the scattering cross section in a shell-shielded Coulomb potential has been derived and is found to be in good agreement with the present experimental results. For thin films the observed backscatter yield is not proportional to the film thickness, but increases more rapidly. The enhancement in the yield can be explained by small-angle multiple deflections. It has been corrected for, using estimates for the angular divergence of a beam passing through a thin stopping region.