Measuring the Decay of Vorticity in Superfluid 3He-B - A Progress Report

Recent measurements in superfluid ³ He-B have been interpreted as evidence in support of the Kibble-Zurek hypothesis for the formation of defects in the early Universe. The superfluid ³ He analogue to the cosmic string is the quantum vortex. We report here the preliminary attempts to detect the heat evolution from the decay of this vorticity in superfluid ³ He-B at temperatures down to 110 K. We produce vorticity by neutron irradiation of a small superfluid ³ He-B sample and attempt to measure the heat released as the vorticity decays. We detect a long time scale heat release and find that the lifetime of this decay varies inversely proportional to the quasiparticle excitation number density in the superfluid. However, we have yet to be convinced that this heat is from the decay of vorticity.