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Behavior of quartz forks oscillating in isotopically pure He-4 in the T -> 0 limit

Garg, Deepak and Efimov, V. B. and Giltrow, M. and McClintock, P. V. E. and Skrbek, L. and Vinen, W. F. (2012) Behavior of quartz forks oscillating in isotopically pure He-4 in the T -> 0 limit. Physical Review B, 85 (14). -. ISSN 1098-0121

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    Abstract

    We report that at low drives, the resonant frequencies and linewidths of nominally 32-kHz quartz tuning forks oscillating in isotopically pure superfluid He-4 at similar to 10 mK are dependent on the dimensions of their environment. We confirm the importance of coupling between forks and acoustic modes within the cell, and develop a theory of their coupled dynamics to account for the observations. The frequencies and linewidths are reproducible on a time scale of tens of minutes, but pronounced drifts are seen over longer intervals. We suggest that the drifts are attributable to changes in the velocity of sound due to tiny pressure changes. In studies at high drives, we observe two critical velocities: v(c1) approximate to 0.6 cm/s, where the drag may either increase or decrease, depending on the linewidth; and v(c2) approximate to 10 cm/s, above which there seems to be fully turbulent flow. At high drives, the behavior of the drag differs markedly between forks that appear otherwise to be very similar.

    Item Type: Article
    Journal or Publication Title: Physical Review B
    Additional Information: ©2012 American Physical Society
    Subjects: Q Science > QC Physics
    Departments: Faculty of Science and Technology > Physics
    ID Code: 54940
    Deposited By: ep_importer_pure
    Deposited On: 07 Jun 2012 15:05
    Refereed?: Yes
    Published?: Published
    Last Modified: 09 Apr 2014 23:38
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/54940

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