Abstract
The dynamic structure factor of a He and Ne gaseous mixture at and total number density has been measured by inelastic neutron scattering at small angles. In the range of wave vectors studied, , we find clear side peaks at frequencies following the hydrodynamic sound dispersion of the binary mixture (with the adiabatic sound speed in the mixture). Surprisingly, neither fast modes nor a transition from normal to fast sound are observed in the above low- region, indicating that hydrodynamic behavior persists up to values which are larger than those predicted by theories and computer simulations.
- Received 21 September 2000
DOI:https://doi.org/10.1103/PhysRevLett.86.1019
©2001 American Physical Society