Some Input Functions for Anisotropic Neutron Scattering

Expressions have been derived for computing the effects of anisotropic neutron scattering in the center-of-mass system on the average cosine and the average cosine squared of the scattering angle in the laboratory system, the average logarithmic energy decrement per collision, the average square of the logarithmic energy decrement per collision if the angular distribution of the neutron scattering cross section in the center-of-mass system in known. In a Legendre polynomial representation, the effect of scattering anisotropy is to require additive correction terms to the usual isotropic scattering approximations for these parameters. The magnitudes of the correction terms depend on the mass of the scattering atom and the degree of anisotropy exhibited by the scattering cross section in the center-of-mass system.