NEUTRON SOURCE ENERGY ON RESONANCE-ABSORPTION

Four different methods are used to study the neutron slowing down and to evaluate the neutron resonance escape probability in an infinite ho mogeneous medium containing a heavy resonant nuclide [U238] and a ligh t moderator nuclide [H]. Two statistical methods use the Monte Carlo s imulation and two deterministic methods are based on the numerical sol utions of the neutron slowing down equation and a corresponding adjoin t equation with an appropriate adjoint source. This study has been don e for several dilutions and for two neutron source energies (E-s = 676 .45 eV and E-s = 2 MeV). The cut-off energy is placed at 2.77 eV. We h ave found that the direct numerical solution of the neutron slowing do wn equation does not agree with the other three methods. In order to e liminate this disagreement, we have taken account of some corrections concerning the hydrogen cross-section in the thermal region. (C) 1997 Elsevier Science Ltd. All rights reserved.