VORTEX CREATION IN A FAST ADIABATIC EXPANSION THROUGH THE LAMBDA-TRANSITION

Copious vortex line creation in a fast (approximately 3 ms) adiabatic expansion of a volume of liquid He-4 through the lambda transition has been observed. The maximum line density, inferred from measurements o f second sound attenuation, is found to be much larger than that in a comparable expansion from just below the lambda line. The phenomenon w as predicted by Zurek who proposed it as a model of cosmic string crea tion in the false vacuum/true vacuum phase transition of the early uni verse.