Anisotropic Scattering in the S_N Method

The treatment of linear anisotropic scattering in one-group, one-dimensional S_N problems is studied. We conclude, partially on a theoretical basis but primarily from numerical results, that the so-called ‘transport approximation’ by which anisotropic scattering is customarily treated gives inferior results to a new approximation which we propose. This approximation utilizes the diffusion theory relation between neutron current and neutron density and is called the ‘S_N-P₁’ approximation.