Acceleration of the integrated TIGER series of coupled electron/photon Monte Carlo transport codes system

The Integrated TIGER Series (ITS) of coupled electron/photon Monte Carlo transport codes system has been accelerated. This was accomplished by examining the program for inefficient coding and replacing the inefficient methods with more computationally efficient ones. Each member code of ITS was benchmarked and profiled with a specific test case. The profiling results directed the acceleration efforts towards the most computationally intensive subroutines. Techniques for accelerating these subroutines were identified and included replacing linear search algorithms with binary versions, replacing the pseudo random number generator, reducing program memory allocation, and proofing the input files for geometrical redundancies. The accelerated code produced either identical or statistically similar results to that of the original code system. Final benchmark timing of the improved ITS showed a speed up factor of 2.00 for TIGER (the 1-D slab geometry code), 1.74 for CYLTRAN (the 2-D cylindrical geometry code), and 1.90 for ACCEPT (the arbitrary 3-D geometry code). An extra step was added to the use of ITS, but this extra step also increased the usefulness of ITS as a design tool. These improvements are machine portable and easily integrated into an existing ITS code installation.