Neuron 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 homogeneous medium containing a heavy resonant nuclide [U238] and a light moderator nuclide [H]. Two statistical methods use the Monte Carlo simulation and two deterministic methods are based on the numerical solutions of the neutron slowing down equation and a corresponding adjoint equation with an appropriate adjoint source. This study has been done for several dilutions and for two neutron source energies (Es = 676.45 eV and Es = 2 MeV). The cut-off energy is placed at 2.77 eV. We have found that the direct numerical solution of the neutron slowing down equation does not agree with the other three methods. In order to eliminate this disagreement, we have taken account of some corrections concerning the hydrogen cross-section in the thermal region.