Interpretation of Electron Scattering Experiments

Abstract

Experiments on the elastic scattering of fast electrons by several elements, reported by Hofstadter, Fechter, and McIntyre in the preceding paper, are interpreted with the help of the first Born approximation. This interpretation of the experiments implies nuclear charge distributions that are peaked at the center and taper off smoothly. The root-mean-square radii of the charge distributions, and the nuclear Coulomb energies, are, however, in approximate agreement with those computed from the usual uniform charge distribution. The effects of radiation loss and nuclear excitation are discussed qualitatively, and the effect of a nuclear electric quadrupole moment is considered more quantitatively. It is concluded that these effects probably cannot account for the discrepancy between the observed scattering cross section which decreases monotonically with increasing angle and the diffraction minima and maxima expected on the basis of the Born approximation from a uniform charge distribution with a sharp or moderately rounded edge. Exact calculations of the elastic scattering from various charge distributions are now under way.