COMPARISON OF DISCRETE-ORDINATES AND MONTE CARLO CALCULATIONS WITH MEASUREMENTS OF FAST NEUTRON SPECTRA IN PARAFFIN SHIELDS.
Technical rept. 17 Feb-17 Oct 66,
GENERAL DYNAMICS SAN DIEGO CA GENERAL ATOMIC DIV
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Measurements of the fast neutron angular flux spectrum in CH2 have been made in point-source, cylindrical geometry, using the same time-of-flight method previously applied to spherical and infinite medium geometries. This work is a continuation of the comparison of accurate, detailed, high-resolution measurements with DTF-IV discrete-ordinate and O5R Monte Carlo calculations. The sphere experiment was reanalyzed with a P16 Gauss-Legendre quadrature set in DTF-IV using the best available evaluated cross sections and P3 scattering. Reasonably good agreement was found except near 0 deg. where the discrete-ordinate code fails to calculate the very anisotropic flux. 05R calculations were made with a more complete description of the spectrum and angular distribution of the source neutrons, and included the continuum inelastic scattering, using new source generator and general inelastic scattering subroutines written for this research. Differences were small. An angular flux cylinder analysis program was written for 05R and unbiased calculations were made for the cylinder. Variance-reduction schemes are needed, however, for a meaningful comparison with the cylinder measurements. The DTF-IV code 1DF version was put into operation on the Kirtland CDC6600 computer and the report includes input instructions. Author
- Nuclear Physics and Elementary Particle Physics