Evaluation of cold neutron scattering cross sections for light and heavy water

Cross section models for cold and thermal neutron scattering from light and heavy water are developed. They are based on the proper treatment of molecular motions in the water in terms of the diffusive and oscillatory translational motions of a water molecule and the intermolecular space-time correlations for highly bonded molecules. Intramolecular motions such as hindered rotations and internal harmonic vibrations are also included. The total and differential scattering cross sections are calculated for a wide range of incident neutron energies from very cold to epithermal. Good agreement with available experimental results permits us to generate basic cross section libraries for the evaluation of cold and ultracold neutron production