Improved Thermal Neutron Scattering Kernels for Liquid Hydrogen and Deuterium

Recent experimental information about the dynamics and structure of liquid hydrogen and deuterium has been used to produce new descriptions of the interaction of slow neutrons with these cryogenic moderators. These models were employed as input data to generate new scattering cross-section libraries using the NJOY code. The molecular translational motion, for both diffusive and collective degrees of freedom, has been reanalysed and represented by different spectral frequency distributions compared to those originally built into the code. Recent structural studies of liquid deuterium are considered in the present work, to use a realistic structure factor for the calculation of the scattering law at different temperatures within the ranges corresponding to the liquid phase of H2 and D2. The preliminary validation tests performed so far using the new libraries indicate that they are able to produce results in better agreement with the experiments than the existing ones.