Torsional oscillator studies of the superfluidity of 3He in aerogel

We have made simultaneous torsional oscillator and transverse NMR measurements (at similar to 165kHz) on He-3 contained within aerogels with nominal densities of 1% and 2% of solid glass. The superfluid transition is seen simultaneously by both techniques and occurs at a temperature which agrees semi-quantitatively with that expected for homogeneous isotropic pair-breaking scattering of He-3 atoms by strands of silica. Values obtained for the superfluid density rho(s) in the 2% sample are in reasonable agreement with those observed previously. Coupling of the torsional mode to a parasitic resonance prevented accurate determination of rho(s) for the 1% aerogel. We have identified other resonances coupling to the torsional oscillations as sound modes within the helium/aerogel medium. (C) 1998 Elsevier Science B.V. All rights reserved.