Absolute Wirkungsquerschnitte für Elektronenstreuung um kleine Winkel Experimente zum Gültigkeitsbereich der ersten Bornschen Näherung

Abstract

The cross sections ofIbers andVainshtein are the current basis for the discussion of the small-angle scattering of electrons. As these cross sections have been calculated in the first Born approximation the limits of their validity are but roughly known. By absolute measurements of the cross sections for Ar, Kr, and Xe at 37, 60, and 100 keV between 5 and 65 mrad the range in which the Ibers and Vainshtein values are no longer valid was determined. The agreement with these values was good for Ar at all energies and for Kr at 60 and 100 keV. In the other cases deviations have been found which increase with increasing angle and atomic number and decreasing energy. Similar results have been found by measurement of the cross sections for inelastic scattering and comparison with the corresponding theoretical results ofFreeman andWatson.