Diffusion Length for Arbitrarily Anisotropic Scattering

For the case of arbitrarily anisotropic scattering in monoenergetic neutron transport theory with no multiplication, the smallest root κ₀ of the determinantal equation (which is equal to the inverse of the diffusion length) is considered as given by an infinite series in powers of the absorption parameter, where Σ_a is the macroscopic absorption cross section and Σ is the total macroscopic cross section. It is shown that α_m depends only on the first m Legendre moments of the scattering probability.