Investigating Many-Electron Exchange Effects in Electron-Heavy-Atom Scattering

S. Bellm
J. Lower
Z. Stegen
Don H. Madison, Missouri University of Science and Technology
H. P. Saha

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In a recent publication we presented measurements and distorted-wave Born approximation (DWBA) calculations for spin asymmetries resulting from the scattering of 148 eV spin-polarized electrons from ground-state xenon atoms. While achieving reasonably good agreement between theory and experiment by accounting for many-body exchange effects through a local exchange potential, sizable discrepancies remained in some cases. It was proposed that a more sophisticated treatment of exchange might be the key to obtaining better agreement. Here we present high-precision experimental results at a lower projectile-electron energy of 112 eV. Due to improvements made to our spectrometer, these data are of significantly-improved statistical accuracy over those obtained previously. They are compared to DWBA calculations, within whose framework electron exchange is treated in three different ways. In the first, only exchange between the projectile electron and ejected target electron is considered and that between the continuum- and bound-electrons is ignored. In the second, exchange between the continuum- and bound-electrons is treated through a local approximation. Finally, exchange is included through a Hartree-Fock (HF) calculation of wave functions for both bound- and continuum-electrons. While this more sophisticated treatment of exchange narrows the gap between experiment and theory, the results suggest improvements in other aspects of the problem may be warranted.