Upgrading physics packages for LAHET/MCNPX

A number of the physics capabilities have been upgraded in the development version of LAHET for the eventual use in MCNPX. These include a high-energy generator for particle interactions, complete definition for particle reaction and elastic scattering cross sections, a current mass excess tabulation, and an improved stopping power formulation. These developments are reported in this paper, along with some identification of the areas of continuing effort.