0000000000860544
AUTHOR
J. R. Hook
First and second viscosity measurements in superfluid 3He-B
By means of diaphragm-driven flow experiments in 3He-B in a thin slab geometry, we have measured the first and second viscosities, η and 3 at pressures of 0, 5, 10 and 29.3 bar. Our measurement of 3 has better established theoretical foundations than previous measurements and also extends to higher pressures. 3 and η were deduced from the frequency dependence of the flow dissipation determined from bandwidth measurements for several normal modes of the diaphragm; a first order slip correction was used in the determination of η. Near Tc, 3 α (1 - T/Tc)-1/2 in accordance with theoretical predictions but below T/Tc ~ 0.6 we observe a rapid drop in 3 signifying a departure from the hydrodynamic…
Momentum creation by vortices in 3He experiments as a model of primordial baryogenesis
We show that recent 3He experiments at Manchester demonstrate the creation of excitation momentum (momentogenesis) by quantized vortices, a process analogous to baryogenesis within cosmic strings. Since superfluid 3He is the most complex field theoretic system available in the laboratory, this experiment gives a firmer foundation to chiral anomaly calculations for baryogenesis on non-trivial backgrounds of the Higgs field such as cosmic strings.
Metastability and hysteresis of the vortex states in rotating superfluid3He-B
We have investigated the vortex core transition in 3He-B by measuring the associated changes in mutual friction dissipation within the superfluid. If rotation is continuously stopped and restarted while cooling or warming then the transition occurs at a clearly defined temperature, but temperature sweeps during continuous rotation show substantial supercooling and superheating. Moreover, the high temperature vortex shows a continuum of metastable states when supercooled to a constant, arbitrary low temperature, the mutual friction dissipaton depending on the temperature at which rotation was started. Our current interpretation is that the high temperature vortex state is a temperature-depen…
Vortex mutual friction in rotating superfluid 3He
The Manchester rotating cryostat has been used to measure the longitudinal and transverse coefficients of vortex mutual friction in the A and B phases of superfluid 3He. In the B phase the dominant contribution to the mutual friction is scattering of excitations off occupied bound states in the vortex core. The A phase results are explained quantitatively by assuming that doubly quantised continuous vortices are created with a dynamics determined by the equation of motion of the orbital vector I; the measurements enable us to put an upper limit on the orbital inertia of less than 0.01h{stroke} per Cooper pair. History-dependent textural effects which had to be overcome in order to make mean…