title: The interpretation of polycrystalline coherent inelastic neutron scattering from aluminium.
abstract: A new approach to the interpretation and analysis of coherent inelastic neutron scattering from polycrystals (poly-CINS) is presented. This article describes a simulation of the one-phonon coherent inelastic scattering from a lattice model of an arbitrary crystal system. The one-phonon component is characterized by sharp features, determined, for example, by boundaries of the (Q, ω) regions where one-phonon scattering is allowed. These features may be identified with the same features apparent in the measured total coherent inelastic cross section, the other components of which (multiphonon or multiple scattering) show no sharp features. The parameters of the model can then be relaxed to improve the fit between model and experiment. This method is of particular interest where no single crystals are available. To test the approach, the poly-CINS has been measured for polycrystalline aluminium using the MARI spectrometer (ISIS), because both lattice dynamical models and measured dispersion curves are available for this material. The models used include a simple Lennard-Jones model fitted to the elastic constants of this material plus a number of embedded atom method force fields. The agreement obtained suggests that the method demonstrated should be effective in developing models for other materials where single-crystal dispersion curves are not available.
authors.affiliation: Physics and Materials Research Centre, University of Salford, The Crescent, Salford, Greater Manchester M5 4WT, United Kingdom.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Roach
authors.forename: D Keith
authors.initials: DK
authors.lastname: Ross
authors.forename: Julian D
authors.initials: JD
authors.lastname: Gale
authors.forename: Jon W
authors.initials: JW
authors.lastname: Taylor
keywords: polycrystalline coherent inelastic neutron scattering