Cryogenic microjet for exploration of superfluidity in highly supercooled molecular hydrogen

We describe a new approach to producing a sample of supercooled molecular para-hydrogen (pH2) at temperatures down to $1.3\un{K}$, well below the predicted superfluid transition temperature for pH2. Unique features of the present scheme are 1) the suppression of both homogeneous and heterogeneous nucleation processes and 2) the possibility to control the liquid temperature in a wide range across the transition. As a first step we demonstrate the stable production in vacuum of continuous hydrogen filaments of macroscopic dimensions. This technique coupled to light scattering experiments will enable microscopic investigations of superfluidity in liquid para-hydrogen.