Attenuation and Velocity of Sound in Superfluid Helium

Abstract

The attenuation and velocity of sound in liquid ${\mathrm{He}}^{4}$ have been calculated using the Landau-Khalatnikov kinetic equations and the phonon Boltzmann equation. A detailed comparison between theory and experiment is made at 0.35\ifmmode^\circ\else\textdegree\fi{}K and good agreement is obtained over a wide range of requencies.