Neutron Scattering in Ortho- and Parahydrogen

Abstract

The cross section for the scattering of cold neutrons by parahydrogen is sensitive to the range of the forces in the triplet state. To facilitate the determination of the range from such measurements, expressions have been obtained for the dependence of the ortho and para cross sections on neutron energy and hydrogen temperature. The interpretation of transmission measurements is complicated by the existence of radiative capture, which is comparable in importance to scattering in parahydrogen. The different energy dependence of the two processes should permit an accurate determination of the individual cross sections.