The Theory and Application of SMART Electron Scattering Matrices

SMART (simulation of many accumulative Rutherford trajectories) scattering theory is based on a scattering matrix designed to eliminate angular and possibly energy discretization errors. This is done without resorting to negative matrix elements. In effect, the true scattering law is replaced by one with fewer collisions but larger deflections per collision. The two scattering laws are equivalent, at least in space-independent calculations. To the extent that this equivalence holds true for space-dependent problems, the major numerical obstacle to electron transport modeling is removed. SMART scattering theory has been used in one-dimensional streaming ray and two-dimensional S_N codes in lieu of Fokker-Planck or extended transport correction techniques, and in a one-dimensional discrete angle Monte Carlo code in place of the condensed history approach. Excellent results have been obtained.