New concepts on the A-B transition in superfluid 3He

There is no doubt that the A-B transition in He-3 can be triggered by neutrons, or some other radiation, which locally heats the liquid into the normal state with consequent fast cooling through T-c. Many experiments show a very small probability for this triggering process. In a new scenario that we call "Venice" we consider the fast local cooling through T-c, with simultaneous and independent creation of many superfluid seeds of different order parameter. The stochastic process of triggering the A-B transition can be explained as the formation of a sufficiently big cluster of B-phase seeds. We consider the statistical conditions required for the triggering of the A-B transition. (C) 2000 Elsevier Science B.V. All rights reserved.