Scattering of Slow Electrons from Helium Atoms

The effect of Pauli exchange on the elastic scattering of a fermion from a many-fermion system has been studied in the context of the "no-polarization" approximation. Calculations of the low-energy elastic-scattering cross sections of electrons on helium atoms have been performed in order to investigate various effects in this approximation. It is shown that the "post" and "prior" forms give essentially identical results when calculated exactly with correct spatially correlated target wave functions. The results also indicate the importance of including all exchange terms and using accurate representations of the target wave function.