Mass Coupling and Q −1 of Impurity-Limited Normal 3He in a Torsion Pendulum
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We present results of the Q −1 and period shift, ΔP, for 3He 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 −1 and mass coupling of the impurity-limited 3He 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, ΔP, 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 3He 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 −1 and period shift for bulk 3He.
KeywordsImpurity limited transport Normal 3He
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