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- Title
Mass Coupling and Q of Impurity-Limited Normal He in a Torsion Pendulum.
- Authors
Bennett, R.; Zhelev, N.; Fefferman, A.; Fang, K.; Pollanen, J.; Sharma, P.; Halperin, W.; Parpia, J.
- Abstract
We present results of the Q and period shift, Δ P, for 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 μm tall pancake (after compression) similar to an Andronikashvili geometry. The result is a high Q pendulum able to resolve Q and mass coupling of the impurity-limited 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, Δ P, between 100 mK and 3 mK that is 2.9% of the period shift (after filling) at 100 mK. The Q due to the He decreases by an order of magnitude between 100 mK and 3 mK at a pressure of 0.14±0.03 bar. We compare the observable quantities to the corresponding calculated Q and period shift for bulk He.
- Subjects
TORSION pendulums; AEROGELS; VISCOSITY; SUPERFLUIDITY; SIGNAL-to-noise ratio; ELECTRIC oscillators; ELASTIC scattering
- Publication
Journal of Low Temperature Physics, 2011, Vol 162, Issue 3/4, p174
- ISSN
0022-2291
- Publication type
Article
- DOI
10.1007/s10909-010-0295-z