Impact of Importance Quality in Coupled Electron- Photon-positron Simulation Using Splitting/rouletting Vr Techniques

The detailed simulation of the full electron-photon cascade may require large computational resources to obtain adequate statistics in a reasonable amount of time. Therefore, the study of variance reduction techniques for this class of problem is necessary. This paper studies the impact of the quality of the importance function (with a specific focus on deterministic importance function) used for transport biasing in a coupled electron-photon-positron Monte Carlo simulation using splitting/rouletting variance reduction techniques. More specifically, this work addresses the issue of the degradation of the performance and accuracy when explicit positron biasing is not performed for such methodologies.