Accession Number : ADA461547


Title :   Simulation of HEAO 3 Background


Corporate Author : GEORGE MASON UNIV FAIRFAX VA


Personal Author(s) : Graham, B L ; Phlips, B F ; Kroeger, R A ; Kurfess, J D


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a461547.pdf


Report Date : Jan 2007


Pagination or Media Count : 6


Abstract : A Monte Carlo technique for modeling background in space-based gamma-ray telescopes has been developed. The major background components included in this modeling technique are the diffuse cosmic gamma-ray flux, the Earth's atmospheric flux, the decay of nuclei produced by spallation of cosmic rays, trapped protons and their secondaries, the decay of nuclei produced by neutron capture, and the de-excitation of excited states produced by inelastic scattering of neutrons. The method for calculating the nuclear activation and decay component of the background combines the low Earth orbit proton and neutron spectra, the spallation cross sections from Alice91, nuclear decay data from the National Nuclear Data Center's (NNDC) Evaluated Nuclear Structure Data File (ENSDF) database, and three-dimensional gamma-ray and beta transport with Electron Gamma-ray Shower version 4 (EGS4). This Monte Carlo code handles the following decay types: electron capture, Beta- Beta+, meta-stable isotopes and short lived intermediate states, and isotopes that have branchings to both Beta- and Beta+. Actual background from the HEAO 3 space instrument is used to validate the code.


Descriptors :   *MONTE CARLO METHOD , *ASTRONOMICAL OBSERVATORIES , DATA BASES , SIMULATION , GAMMA RAYS , SPACE BASED , COSMIC RAYS , NUCLEAR STRUCTURE , NEUTRON CAPTURE , INELASTIC SCATTERING , ELECTRON CAPTURE , TELESCOPES , PROTONS , EARTH ORBITS


Subject Categories : Astronomy


Distribution Statement : APPROVED FOR PUBLIC RELEASE