1981 Construction of a rotating nuclear refrigeration cryostat, capable of cooling liquid 3He down to 0.3 mK, is completed in the Low Temperature Laboratory. 1982 NMR measurements on 3 He-B prove that the vortex core undergoes an unexpected phase transition. The two different vortices belong to the same topological class but possess cores with different structures. This observation triggers renewed theoretical efforts to investigate the symmetry and topology of the vortex core. The singular vortex core in 3 He-B is found to display a spontaneous ferromagnetic moment, manifested by the gyromagnetic effect.
Theoretical investigation shows that parity is spontaneously broken inside the core .
He-A are obtained from measurements on the propagation of negative ions through rotating superfluid. The nature of the vortex core transition in 3 He-B is explained. On the low temperature side, the core splits into two so that axial symmetry is broken. In contrast, the high temperature vortex is axisymmetric. 1988 Construction of the second rotating cryostat in the LTL is completed.