Half widths of neutron spectra in dense helium-neon gas mixtures.

Abstract

Results are presented of seven inelastic-neutron-scattering experiments on dense gas mixtures of helium and neon, performed on the Interfaculty Reactor Institute time-of-flight spectrometer RKS2. The concentration ratio of neon in the mixture is varied from 0 to 1 at 47 K and 285 bar. The neutron spectra S(k,\ensuremath{\omega}), obtained for wave numbers 2.5k30 ${\mathrm{nm}}^{\mathrm{\ensuremath{-}}1}$, are centered around the frequency \ensuremath{\omega}=0 with half widths ${\mathrm{\ensuremath{\omega}}}_{\mathit{H}}$(k). The experimental ${\mathrm{\ensuremath{\omega}}}_{\mathit{H}}$(k) agree well with the revised Enskog theory for equivalent binary hard-sphere fluid mixtures and show de Gennes minima similar to those in monoatomic fluids.