Monte Carlo Calculation of Neutrons Transmitted through Matter

Abstract

The neutron Monte Carlo code, CYGNUS, which is written in Fortran IV has been shown. This code can easily be used for several limitted geometries and requires considerably less computing time than O5R. In this paper, two methods of calculation are described : one by weight method and the other by collision density method, and the two techniques for determination of the anisotropic scattering angle in the center-of-mass system, i.e., Legendre expansion and Coveyou technique, and the method for determination of the excited level in the inelastic scattering are also described. The results calculated with CYGNUS code are compared with the numerical solution by PALLAS code for the sealer flux in water and graphite spheres, and with experimental spectra for the angular neutron flux in water and iron shields. The agreement obtained between the CYGNUS calculations and numerical or experimental results is good.