Upgrading physics packages for LAHET/MCNPX

A number of the physics capabilities have been upgraded in the development version of LAHET for the eventual use in MCNPX. These include a high-energy generator for particle interactions, complete definition for particle reaction and elastic scattering cross sections, a current mass excess tabulation, and an improved stopping power formulation. These developments are reported in this paper, along with some identification of the areas of continuing effort

CEM2k and LAQGSM as Event Generators for Space-Radiation-Shielding and Cosmic-Ray-Propagation Applications

The CEM2k and LAQGSM codes have been recently developed at Los Alamos National Laboratory to simulate nuclear reactions for a number of applications. We have benchmarked our codes against most available measured data at incident particle energies from 10 MeV to 800 GeV and have compared our results with predictions of other current models used by the nuclear community. Here, we present a brief description of our codes and show illustrative results to show that CEM2k and LAQGSM can be used as reliable event generators for space-radiation-shielding, cosmic-ray-propagation, and other astrophysical applications. Finally, we show the use of our calculated cross sections together with experimental data from our LANL T-16 compilation to produce evaluated files which we use in the GALPROP model of galactic particle propagation to better constrain the size of the CR halo.Comment: 10 pages, 9 figures, LaTeX, talk given at the World Space Congress 2002, 34th COSPAR Scientific Assembly, Houston, Texas, USA, 10-19 October 2002, to appear in Advances in Space Researc

The LAHET code system: Introduction, development, and benchmarking

An introduction to the LAHET code system is presented, showing the function of each code and their interrelation. A summary is made of the principal physics models used in LAHET. Some recent results in benchmarking axe shown for small-angle neutron emission from [sup 7]Li for 800 MeV protons incident, neutron emission from [sup 9]Be at several incident proton energies, and actinide and subactinide fission ratios

Benchmarking the LAHET{trademark} fission models

There has been considerable interest in improving the fission models in the LAHET Monte Carlo code for the transport and interaction of nucleons, pions, muons, light ions, and antinucleons. Although subactinide fission contributes little to neutron production in lead or tungsten targets, it can be significant for simulation of target activation and fission product contamination. The availability of new data permits new comparisons to be made between experiment and calculation

Monte Carlo next-event estimates from thermal collisions

A new approximate method has been developed by Richard E. Prael to allow S({alpha},{beta}) thermal collision contributions to next-event estimators in Monte Carlo calculations. The new technique is generally applicable to next-event estimator contributions from any discrete probability distribution. The method has been incorporated into Version 4 of the production Monte Carlo neutron and photon radiation transport code MCNP. 9 refs

MCNP S(. alpha. beta. ) detector scheme

An approximate method to allow S({alpha},{Beta}) thermal collision contributions to point detectors and DXTRAN by Prael has been implemented in MCNP4. The method is described and test results are presented, including some results that indicate inadequacies in the NJOY processing of the nuclear data. 9 refs., 53 figs., 6 tabs

Addendum to: Applications of evaluated nuclear data in the LAHET code

This document is intended to provide additional information supplementing a prior publication. The discussion describes the details of the implementation of the proton nonelastic cross section parameterization for LAHET usage. It also documents extensions of the method to stable nuclei with 2 {le} Z {le} 5

A nucleon-nucleus elastic scattering model for LAHET{trademark}

A model for elastic scattering of protons and neutrons has been adapted for the LAHET Monte Carlo code. New optical-model cross sections are included, as well as a new algorithm for sampling the scattering distribution

Adaptation of a nucleon-nucleus elastic scattering model for LAHET{trademark}

The LAHET Monte Carlo code for the transport and interaction of nucleons, pions, muons, light ions, and antinucleons has been upgraded by the addition of an elastic scattering model for neutrons above 15 MeV and protons above 50 MeV. Earlier elastic scattering in LAHET has been limited to neutrons below 100 MeV, using a library of elastic optical-model cross sections generated using the Bechetti-Greenlees potential. The new methodology has been adapted from the HERMES code. However, the sampling algorithm for the center-of-mass scattering angle has been completely rewritten, and the elastic cross section data has been replaced below 400 MeV. The new method is viewed as an intermediate step in the effort to provide a library of both elastic and non-elastic cross sections from a global optical-model potential for LAHET usage