Role of an Electron Screened Mott–Schwinger Interaction in the Elastic Scattering of Neutrons

Abstract

The Mott–Schwinger potential arising from the interaction of the magnetic moment of a neutron incident upon the (electric) field of a nucleus has a profound effect upon the cross sections for scattering. The purely nuclear interaction (hadronic plus Mott–Schwinger) leads to a divergence in the spin–flip scattering amplitude at 0° scattering and thus to a divergent total scattering cross section. We demonstrate that the screening of this interaction caused by the atomic electron cloud essentially compensates that divergence so that the scattering cross-section values, to be used for example in reactor moderation calculations, are effectively those given by calculations made without consideration of any Mott–Schwinger potential. However, the forward scattered neutrons remain strongly polarised as a result of the (complete) Mott–Schwinger interaction.