Modelling Neutron Transport in Planetary Media via Analytical Multigroup Diffusion Theory

A novel analytical solution to the 1-D, steady-state, multi-slab, multi-group diffusion equation is proposed as a mean to compute the energy-dependent GCRs-induced neutron fluxes established in planetary media. More specifically, the proposed algorithm is implemented to allow fast and highly accurate determination of low energy cosmic ray neutrons inside Earth’s surface and atmosphere. Two sets of experimental measurements have been considered to validate our model. In both cases a good agreement between the calculated and observed neutron fluxes is achieved. Subsequently, neutron diffusion calculations have been performed for various Earth-based scenarios comprising a) two-slab (air-soil) configuration and b) three-slab (air-soil-ice) configuration to investigate the functional relationship between soil composition and neutron spatial distribution.