HALF WIDTHS OF NEUTRON-SPECTRA IN DENSE HELIUM-NEON GAS-MIXTURES

Results are presented of seven inelastic-neutron-scattering experiment s on dense gas mixtures of helium and neon, performed on the Interfacu lty Reactor Institute time-of-flight spectrometer RKS2. The concentrat ion ratio of neon in the mixture is varied from 0 to 1 at 47 K and 285 bar. The neutron spectra S(k,omega), obtained for wave numbers 2.5 < k < 30 nm-1, are centered around the frequency omega=0 with half width s omega(H)(k). The experimental omega(H)(k) agree well with the revise d Enskog theory for equivalent binary hard-sphere fluid mixtures and s how de Gennes minima similar to those in monoatomic fluids.