With the release of MCNP 5, much more emphasis has been placed on improving its functionality on PCs running Microsoft Windows (9X/NT/2000/XP). Enhanced installation and build systems, support for more Fortran compilers, integration with X11 graphics build files, and MPI and PVM parallel capabilities have been implemented in MCNP 5 for Windows PCs. MCNP 5 can be installed with an InstallShield setup programs, similar to other Windows programs, for users who only need to install executables and data libraries. For those users who need to compile the source, the GNU make utility can used in conjunction with three supported Fortran compilers: Compaq Visual Fortran (CVF), Lahey Fortran 95 (LF95) or Absoft Fortran 95 (AF95). Alternatively, Compaq Developer Studio can be used to compile MCNP 5. The X-Windows plotting capabilities have been improved, and all the appropriate open source X11R6 files for compiling MCNP 5 are bundled with the MCNP 5 source code. X client software is still needed, however, to display geometry, cross-section or tally plots. Parallel capabilities which exist on other platforms have been extended to Windows PCs, allowing users to utilize dual CPU PCs, clusters of homogeneous Windows PCs (preferably with MPI), or heterogeneous clusters (preferably with PVM). Wall-clock runtimes show that MCNP 5 compiled with CVF runs 1.4 times faster than when it is compiled with LF95 or AF95. Wall-clock runtimes also show MCNP 5 with MPI more effectively utilizes a dual-processor Windows 2000 PC than MCNP 5 with PVM.

This talk summarizes the main aspects of the LANL ASCI Eolus project and its major unclassified code project, MCNP. The MCNP code provide a state-of-the-art Monte Carlo radiation transport to approximately 3000 users world-wide. Almost all hardware platforms are supported because we strictly adhere to the FORTRAN-90/95 standard. For parallel processing, MCNP uses a mixture of OpenMp combined with either MPI or PVM (shared and distributed memory). This talk summarizes our experiences on various platforms using MPI with and without OpenMP. These platforms include PC-Windows, Intel-LINUX, BlueMountain, Frost, ASCI-Q and others.

The Monte Carlo transport workhorse, MCNP, is undergoing a massive renovation at Los Alamos National Laboratory (LANL) in support of the Eolus Project of the Advanced Simulation and Computing (ASCI) Program. MCNP Version 5 (V5) (expected to be released to RSICC in Spring, 2002) will consist of a major restructuring from FORTRAN-77 (with extensions) to ANSI-standard FORTRAN-90 with support for all of the features available in the present release (MCNP-4C2/4C3). To most users, the look-and-feel of MCNP will not change much except for the improvements (improved graphics, easier installation, better online documentation). For example, even with the major format change, full support for incremental patching will still be provided. In addition to the language and style updates, MCNP V5 will have various new user features. These include improved photon physics, neutral particle radiography, enhancements and additions to variance reduction methods, new source options, and improved parallelism support (PVM, MPI, OpenMP).

Modern radiation treatment planning for photons includes full 3D modeling of the adsorbed dose distribution, accurate inclusion of the patient anatomy, and consideration of significant changes in material density and composition. Such efforts are founded in an accurate description of the radiation source and the beam delivery system. Modern fast neutron therapy facilities employ highly penetrating beams and isocentric beam delivery. Treatment planning is largely based on analytic models adapted from photon codes and interaction cross sections normalized to macroscopic attenuation. However, the recent PEREGRINE initiative at Lawrence Livermore Laboratory offers the possibility of fully stochastic modeling if the neutron source can be adequately described. In this article we report neutron source modeling of three high energy facilities. Neutron production is based on the intra-nuclear cascade model of the LAHET code while neutron transport through the beam delivery system is managed by MCNP using cross section libraries extended to 100 MeV neutron energy. PEREGRINE is then used to transport the neutron beam through typical phantoms. The resulting neutron sources are in excellent agreement with the limited experimental information and the measured phantom data are well described by the PEREGRINE transport using the LAHET/MCNP determined neutron sources.