The journey of hydrogen to quantized vortex cores
  Nanoscale hydrogen particles in superfluid helium track the motions of quantized vortices. This provides a way to visualize turbulence in the superfluid. Here, we trace the evolution of the hydrogen from a gas to frozen particles migrating toward the cores of quantized vortices. Not only are the intervening processes interesting in their own right, but understanding them better leads to more revealing experiments. 
Gregory P. Bewley and J\"urgen Vollmer
cond-mat.stat-mech cond-mat.other