New Experiments for Spontaneous Vortex Formation in Josephson Tunnel   Junctions
  It has been argued by Zurek and Kibble that the likelihood of producing defects in a continuous phase transition depends in a characteristic way on the quench rate. In this paper we discuss an improved experiment for measuring the Zurek-Kibble scaling exponent $\sigma $ for the production of fluxons in annular symmetric Josephson Tunnel Junctions. We find $\sigma \simeq 0.5$. Further, we report accurate measurements of the junction gap voltage temperature dependence which allow for precise monitoring of the fast temperature variations during the quench. 
R. Monaco, M. Aaroe, J. Myging, R.J. Rivers, V.P. Koshelets