Computational Methods R&D

Laboratory programs require new computational techniques in particle and radiation transport to address complex science and engineering projects with high accuracy. Group members conduct research and development on advanced algorithms to be employed in current and future transport packages.

SIMC – The Symbolic Implicit Monte Carlo effort is developing new methods for solving the time-dependent radiation transport equations.  SIMC methods track photons with symbolic weights and model atomic absorption and emission in materials. A recent theoretical breakthrough has resulted in a new formulation of the radiation transport equations – called the difference formulation. Current effort is being devoted to implementing the difference formulation in order to further improve speed and accuracy in highly opaque media.

RNG – The Random Number Generator package is acollection of algorithms that generate pseudo random numbers between 0 and 1. This generator was designed to support the massively parallel computing simulations of the LLNL Advanced Simulation and Computing Program (ASCI) program. RNG can generate 2⁶⁴ (or 18,446,744,073,709,551,616) numbers without repetition. A new version currently under development will generate 2¹²⁸ numbers.

MCAPM – The Monte Carlo All Particle Method package is a collection of routines that use processed nuclear data to simulate the transport of particles through matter. Currently, MCAPM can track neutrons, protons, deuterons, tritons, ³He, ⁴He, and photons. MCAPM returns the mean free path of the tracked projectile and samples the exiting angles and energies of the secondary particles for each collision.

APT – The All-Particle-Tracking (APT) subroutine library contains over 300 subroutines, primarily for Monte Carlo and geometric applications. It is designed especially to support 2-D and 3-D codes that generate and track particles or beams of matter or energy, and contains subroutines useful in many other kinds of codes. This users' document and other documentation, the ANSI Standard FORTRAN source files, and the compiled binary modules are available on the Open Network GPS Cluster.

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