Neutron transfer kernels in the resonance domain in the harmonic crystal model - 048

To describe neutron scattering in the resonance domain of the nuclear fuel isotopes, the static model is widely in use in nuclear data processing codes. With this model the influence of chemical binding on the transfer cross section is not taken into account since the nucleus is considered to be at rest in the laboratory system. Further, the application of the free gas model to the resonant scattering of neutrons shows that the up-scattering probability is strongly dependent on the incident neutron energy. If the latter is smaller than the resonance energy then the free gas model predicts an enormous chance for the neutron to gain energy after collision. Neither the static nor free gas model is adequate to describe the resonant scattering of neutrons in a crystal. This fact can induce non-negligible errors in reactor calculations and, in particular, in the estimation of the Doppler coefficient. In present paper we propose the theoretical study of the possibility to estimate the neutron transfer cross sections in the harmonic crystal approximation. (author)