A study of neutron diffusion lengths in heterogeneous, non-multiplying plate assemblies

A study of the diffusion length of neutrons in an infinite lattice of alternate slabs of two different materials in the direction parallel to the slabs has been carried out on the basis of integral transport theory. In the one-velocity approximation we obtain, numerically, curves for aluminium water lattices from which one can observe the possibility of the existence or non-existence of a discrete decay constant ν for a given configuration.

In the energy dependent case, two of the configurations studied by Palmedo and Conant have been chosen, and it has been shown that neither of them possesses a discrete decay constant, which is consistent with their experimental findings. The asymptotic spectra in the aluminium and water regions for certain configurations have also been discussed. Calculations are also made for the lead-water systems studied experimentally by Mukhin et al. and satisfactory agreement obtained.