Large-Angle Inelastic Scattering of 500-keV Electrons

Experimental results are given for the energy spectra of electrons inelastically scattered at 100 deg, with 500-keV electrons incident on thin targets of gold and of aluminum. This large-angle inelastic scattering arises primarily from the two processes of bremsstrahlung and of atomic $K$-shell ionization with a small contribution from multiple-scattering effects. In the 300-keV energy region for the scattered electron, the sum of the theoretical cross sections evaluated with the Born calculations of Racah and of Weber, Deck, and Mullin for the respective two processes is approximately an order of magnitude smaller than the experimental values. This disagreement can be attributed to the breakdown in this energy region of both the high-energy approximation in the latter calculation and the Born approximation in both calculations.