Torsional oscillator and synchrotron X-Ray experiments on solid 4He in aerogel.
X-ray diffraction experiments show that solid 4He grown in aerogel is highly polycrystalline, with an hcp crystal structure (as in bulk) and a crystallite size of approximately 100 nm. In contrast to the expectation that the highly disordered solid will have a large supersolid fraction, torsional oscillator measurements show a behavior that is strikingly similar to high purity crystals grown from the superfluid phase. The low temperature supersolid fraction is only approximately 3 x 10(-4), and the onset temperature is approximately 100 mK.
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Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA.
West
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Chan
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Kodituwakku
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Burns
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Lurio
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