New experiments on quantization of circulation in superfluid⁴He

We measure circulation in superfluid⁴He around a thin vibrating wire which can serve as the core of a vortex. As well as confirming earlier measurements of the quantum of circulation, our data yield new information on the dynamics of transitions between stable circulation states. A situation in which a vortex line partially detaches from the wire, with the free end precessing about the wire, is observed.