Number 78 (Story #1), May 4, 1992 by Phillip F. Schewe and Ben Stein|
PHYSICISTS CONFIRM BAKED ALASKA MODEL . Helium-3 will often remain in the superfluid A phase even when the temperature drops low enough for the liquid to enter another distinct superfluid state, the "B" phase, characterized by a change in orientation between helium pairs. Eventually, the B phase does grow from the "supercooled" A phase, but it typically develops at highly unpredictable, irreproducible times. In 1984, Anthony Leggett of the University of Illinois proposed that cosmic rays trigger the phase transition. At the recent APS Meeting in Washington, Peter Schiffer of Stanford showed experimental results in which Co-60 gamma rays, simulating the effect of cosmic ray muons, sped up the onset of the A-B phase transition by up to 1600 times. The results of the Stanford team agree closely with Leggett's model, which is named after "Baked Alaska" (in which meringue is baked around ice cream) because the cosmic rays create ionized electrons which can deposit their energies into localized spots in the liquid, creating cold regions surrounded by hot regions. It is in these cold regions that the B phase has a chance to nucleate and grow throughout the liquid.