Mass coupling and $Q^{-1}ofimpurity-limitednormal$^3$He in a torsion pendulum

Abstract

We present results of the $Q^{-1}$ and period shift, $\Delta P$, for ${}^3$He confined in a 98% nominal open aerogel on a torsion pendulum. The aerogel is compressed uniaxially by 10% along a direction aligned to the torsion pendulum axis and was grown within a 400 $\mu$m tall pancake (after compression) similar to an Andronikashvili geometry. The result is a high $Q$ pendulum able to resolve $Q^{-1}$ and mass coupling of the impurity-limited ${}^3$He over the whole temperature range. After measuring the empty cell background, we filled the cell above the critical point and observe a temperature dependent period shift, $\Delta P$, between 100 mK and 3 mK that is 2.9 of the period shift (after filling) at 100 mK. The $Q^{-1}$ due to the ${}^3$He decreases by an order of magnitude between 100 mK and 3 mK at a pressure of $0.14\pm 0.03$ bar. We compare the observable quantities to the corresponding calculated $Q^{-1}$ and period shift for bulk ${}^3$He.

8 pages, 3 figures

References in corpus (5)

• Strong orientational effect of stretched aerogel on the 3He order parameter
• Orbital glass and spin glass states of 3He-A in aerogel
• Observation of Coherent Precession of Magnetization in Superfluid 3He A-phase
• Stability of the A-like Phase of Superfluid 3He in Aerogel with Globally Anisotropic Scattering
• Superfluid Phase Stability of ${}^3$He in Axially Anisotropic Aerogel

Cited by in corpus (2)

• Modification of the 3He Phase Diagram by Anisotropic Disorder
• Dissipation signatures of the normal and superfluid phases in torsion pendulum experiments with 3He in aerogel