Thermal Neutron Diffusion in an Array of Plates

The exact solution to the diffusion equation for thermal neutrons emitted into an infinite medium containing absorbing and scattering plates is obtained. A fully explicit analytical representation is found through the solution of the resulting recurrence relation for the interfacial fluxes. Departure from Galaninʹs theory, which assumes infinitesimally thin absorbing plates, is demonstrated with increasing absorber thickness and decreasing diffusion coefficient.