IncoherentJ=1→0neutron scattering from solidH2

Abstract

The cross section for the $J=1\ensuremath{\rightarrow}0$ orthohydrogen-parahydrogen conversion by incoherent scattering of neutrons in solid hydrogen is calculated for a variety of $o\ensuremath{-}{\mathrm{H}}_{2}$ concentrations and at temperatures high compared to the angular momentum ordering temperature. It is shown that, just as for the $J=1\ensuremath{\rightarrow}1$ scattering discussed earlier, the $J=1\ensuremath{\rightarrow}0$ scattering depends in a simple way on the $o\ensuremath{-}{\mathrm{H}}_{2}$ angular momentum autocorrelation functions. This reinforces our earlier conclusions that neutron scattering can provide a direct probe of these functions. When taken as a whole, the results presented here and those obtained in our earlier papers on the subject present a complete theoretical picture of high-temperature incoherent neutron scattering from solid mixtures of orthohydrogen and parahydrogen.