Scattering of Slow Neutrons by Water

The motions of hydrogen atoms in water are considered in terms of the ${\mathrm{H}}_2$O molecule at the basic dynamical unit. Vibrations, hindered rotations, and translations of the molecule are included. For the numerical calculations, the hindrance of the translations is neglected, and the hindered rotations are replaced by a torsional oscillation with a single energy, $h\nu =0.06\mathrm{}$ ev. When certain approximations are made in the average over molecular orientation, this model allows for the computation of differential and total slow-neutron cross sections. The computed cross sections are in good agreement with most of the available slow-neutron scattering data. The features of the high-resolution experiments directly associated with the hindrance of the molecular translations in the liquid are not reproduced.