First-Sound Attenuation and Viscosity of Superfluid 3He-B

Abstract

The attenuation of first sound in normal and superfluid 3He in a cylindrical resonator has been measured from 40 kHz to 300 kHz at 8 and 28 bars. In the B phase a decreasing viscosity down to the lowest temperature (0.5Tc) is observed. In the normal phase the viscosity agrees with previously reported values. The data analysis is based on a recent theory of sound propagation in superfluid 3He in a resonator.