Primary and secondary nucleation of the transition between the A and B phases of superfluid 3He
We have studied nucleation in superfluid 3He across the A-B phase transition driven by a magnetic field, in a controllable environment at very low temperatures. Both B-->A and A-->B secondary nucleation appear to be governed by the survival of pockets of the new phase trapped at surfaces. We find that, at fields near B(AB), primary A-->B nucleation cannot be triggered by ionizing or neutron irradiation even at very high intensities. In our cell primary A-->B nucleation can only be triggered externally by mild mechanical shock.
Bartkowiak
M
Department of Physics, Lancaster University, Lancaster, LA1 4YB, United Kingdom.
Fisher
SN
Guenault
AM
Haley
RP
Pickett
GR
Plenderleith
GN
Skyba
P