GAMMA-RAY AND NEUTRON DOSE-EQUIVALENT BUILDUP FACTORS FOR INFINITE SLABS

Gamma-ray and neutron dose-equivalent buildup factors are calculated for six common shielding materials in a point-source, infinite-slab, point-detector geometry using a decomposition of the solution to the transport problem into single- and multiple-scatter components. A rigorous solution for the single-scatter component is constructed and a Monte Carlo model for the multiple-scatter component is employed. Simplified models are fit to the calculated buildup factors as functions of slab thickness and source-detector separation, and model constants are evaluated for each of several source energies. Single-scatter and total slab buildup factors are presented, both in tabular form and in graphs that also show the fitted models, for six materials. The models are demonstrated for a sample problem.