Insights into Stratified Splitting Techniques for Monte Carlo Neutron Transport

Several different stratified splitting techniques for sampling the distance to collision are compared with the standard (unstratified) weight window splitting used in MCNP. The results indicate that typical neutron penetration problems could be modestly more efficient using one of the stratified splitting techniques. For many penetration problems, one of the simplest techniques compares favorably with several more complicated techniques.

As a cautionary note, a very highly scattering neutron penetration problem shows that some stratification techniques do not always reduce the variance of the score distribution.