Torsional Oscillator and Synchrotron X-Ray Experiments on Solid 4He in Aerogel

X-ray diffraction experiments show that solid (4)He 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 similar to 3x10(-4), and the onset temperature is similar to 100 mK.