Novel oscillating aerogel experiments in superfluid He-3 at ultralow temperatures.

Brussaard, Peter and Fisher, Shaun N. and Guénault, A.M. and Hale, A. J. and Pickett, George R. (2000) Novel oscillating aerogel experiments in superfluid He-3 at ultralow temperatures. Journal of Low Temperature Physics, 121 (5-6). pp. 555-560. ISSN 0022-2291

Abstract

We present novel experiments on a disk of 98% aerogel oscillating in super-fluid He-3 at ultralow temperatures. The aerogel disk is attached to a goal post shaped vibrating wire resonator and immersed in liquid He-3 cooled by a Lancaster style nuclear cooling stage. At low pressures we see no evidence for superfluidity within the aerogel down to our base temperature of below < 0.11T(c). At higher pressures we observe large temperature dependent frequency shifts, reminiscent of torsional oscillator experiments. We find the transition temperature at 5 bar to be around 600 <mu>K. The response of the resonator is highly non linear when the helium in the aerogel is superfluid. The resonant frequency decreases strongly with increasing wire amplitude. This offers an exciting new technique for measuring the superfluid properties of He-3 in aerogel in the ultralow temperature regime.