Multiple scattering theory for slow neutrons (from thermal to ultracold)

The general theory of neutron scattering is presented, valid for the whole domain of slow neutrons from thermal to ultracold. Particular attention is given to multiple scattering which is the dominant process for ultracold ne utrons (UCN). For thermal and cold neutrons, when the multiple scattering i n the target can be neglected, the cross-section is reduced to the known va lue. A new expression for inelastic scattering cross-section for UCN is pro posed. Dynamical processes in the target are taken into account and their i nfluence on inelastic scattering of UCN is analyzed.