Optimization of Voxelization Parameters in Geant4 Tracking and Improvement of the Shooter Benchmarking Program

The geometry-based tracking of the ubiquitous particle physics simulation toolkit Geant4 utilizes the idea of voxels, which effectively partition regions into multi-dimensional slices that can decrease simulation time. The extent of voxelization and the size of the voxels is determined by a set of parameters, which until now, defaulted to arbitrary numbers. In this report I document how I tested different values for these parameters and determined which values should be the default. I modified the existing G01 Geant4 example program to get an initial look at how the performance depended on the parameters. Then I modified the Shooter benchmark program, which lacks extraneous physics processes, to collect more refined data and to provide a tool for future testers to perform comprehensive benchmarks. To this end, I created a new geometry, added features to aid in testing over ranges of parameters, and setup the default tests to provide a good sampling of different simulation scenarios.