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Repair for scattering expansion truncation errors in transport calculations. [DOT and MORSE computer codes] [electronic resource].

Published
Oak Ridge, Tenn. : Oak Ridge National Laboratory, 1980.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
Pages: 6 : digital, PDF file
Additional Creators
Oak Ridge National Laboratory and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Legendre expansion of angular scattering distributions is usually limited to P/sub 3/ in practical transport calculations. This truncation often results in non-trivial errors, especially alternating negative and positive lateral scattering peaks. The effect is especially prominent in forward-peaked situations such as the within-group component of the Compton Scattering of gammas. Increasing the expansion to P/sub 7/ often makes the peaks larger and narrower. Ward demonstrated an accurate repair, but his method requires special cross section sets and codes. The DOT IV code provides fully-compatible, but heuristic, repair of the erroneous scattering. An analytical Klein-Nishina estimator, newly available in the MORSE code, allows a test of this method. In the MORSE calculation, particle scattering histories are calculated in the usual way, with scoring by an estimator routine at each collision site. Results for both the conventional P/sub 3/ estimator and the analytical estimator were obtained. In the DOT calculation, the source moments are expanded into the directional representation at each iteration. Optionally a sorting procedure removes all negatives, and removes enough small positive values to restore particle conservation. The effect of this is to replace the alternating positive and negative values with positive values of plausible magnitude. The accuracy of those values is examined herein.
Report Numbers
E 1.99:conf-791103-100
conf-791103-100
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Note
Published through SciTech Connect.
01/01/1980.
"conf-791103-100"
American Nuclear Society meeting, San Francisco, CA, USA, 12 Nov 1979.
Childs, R.L.; Emmett, M.B.; Rhoades, W.A.
Funding Information
W-7405-ENG-26
View MARC record | catkey: 14671268