### A new perspective on some approximations used in neutron transport modeling

In this contribution, we will use the Maxwell-Cartesian spherical harmonics (introduced in [1,2]) to derive a system of partial differential equations governing transport of neutrons within an interacting medium. This system forms an alternative to the well known ${P}_{N}$ approximation, which is based on the expansion of the directional dependence into tesseral spherical harmonics ([3,p.197]). In comparison with this latter set of equations, the Maxwell-Cartesian system posesses a much more regular structure,...