Comparison of relativistic partial wave calculations of triply differential electron-atom bremsstrahlung with simpler theories

C. David Shaffer^*, R. H. Pratt
Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260

Abstract:

The results of our exact partial wave triply differential electron-atom bremsstrahlung calculations are compared with those of simpler theories. This triply differential cross section is expected to provide a more sensitive test of the adequacy of theoretical descriptions of the process than the doubly differential cross section, not observing the scattered electron. Our method is an extension and reformulation of the relativistic partial wave and multipole decomposition method of Tseng and Pratt, which was only used to calculate the doubly differential cross section. We compare our calculations to those using the Bethe-Heitler equation (first Born approximation including form factors) and to calculations using the formalism of Elwert and Haug (which utilize approximate Coulomb wave functions and form factors). We examine silver and heavier elements, where the validity of the simpler theories is in question. For such elements we find no significant region of agreement with the Bethe-Heitler theory. We find some agreement with the theory of Elwert and Haug at small momentum transfers, improving with increasing energy. We find poor agreement of our results with the Elwert-Haug results for large momentum transfers. The differences from simpler theories are indeed much greater in the triply differential cross section than in the double differential cross section.