Big Bang Vortex Formation in Neutron-Irradiated (3)He-B Superflow

摘要

Topological defects formed in a symmetry-breaking phase transition in the earlyUniverse could be responsible for large-scale structure formation, for microwave-background anisotropy and for the observed baryon asymmetry of the Universe. The physics of defect formation is similar to that in condensed matter, and thus may be modelled in the laboratory. In the authors' experiments the 'primoridal fireball' is formed in neutron-irradiated superfluid 3He-B due to the nuclear reaction n + (3 over 2)He = p + (3 over 1)H + 0.76MeV, The subsequent rapid cooling of the locally overheated liquid through the superfluid transition results in the formation of vortex rings. If the 3He-B container rotates, sufficiently large vortex rings grow, escape from the heated bubble, and are detected individually with nuclear magnetic resonance. The larger the rotation velocity the smaller the rings which can expand and the more vortices are observed. Thus it is possible to obtain information about the morphology of the initial defect network and hence decide between different scenarios of defect formation in the early Universe.