BEST Experiment Team Finds First Evidence of Dynamic Finite-Size Scaling

The Boundary Effects at the Superfluid Transition (BEST) Experiment is a collaboration between the University of California, Santa Barbara (PI Prof. Guenter Ahlers) and JPL (Co-PI Feng Liu) to study the effects of a solid boundary and the finite size of the system on critical thermal transport near the superfluid transition of helium-4. The theory of Dynamic Finite-Size Scaling predicts that a set of universal scaling functions govern how the critical thermal transport varies with the size of confinement. The BEST team studied the thermal conductivity (a dynamic variable of the fluid) of 4He confined in highly uniform glass capillary arrays with 0.5 micron and 1.0 micron diameters. The data provides the first experimental evidence in support of the Dynamic Finite Size Scaling theory. BEST scientist Dr. Edgar Genio (UCSB) presented the latest results at the American Physical Society's March, 2001 meeting in Seattle. A more rigorous verification of the theory over a wide parameter range requires a microgravity environment free of gravity smearing. BEST will conduct the microgravity measurement on the second mission of the Low Temperature Microgravity Physics Facility on the International Space Station.