Superfluidity in a Doped Helium Droplet

Superfluidity in a doped helium droplet.

Path-integral Monte Carlo calculations of the superfluid density throughout 4He droplets doped with linear impurities are presented. After deriving a local estimator for the superfluid density distribution, we find a decreased superfluid response in the cylindrically symmetric region of the first solvation layer. The helium in this region has a superfluid transition temperature similar to that ...

Superfluidity in Solid Helium-4

Universal molecule injector in liquid helium: Pulsed cryogenic doped helium droplet source

Progress toward the construction of a universal molecule injector for doping bulk liquid helium is reported. A pulsed valve that operates at cryogenic temperatures, down to 4 K, is demonstrated within the confinement of a cryostat, operating in the vapor above a steady level of liquid He. The insulated valve can be operated at elevated temperatures with preseeded helium gas in supersonic expans...

Helium Droplets Doped with Sulfur and C60

Clusters of sulfur are grown by passing superfluid helium nanodroplets through a pickup cell filled with sulfur vapor. In some experiments the droplets are codoped with C60. The doped droplets are collided with energetic electrons and the abundance distributions of positively and negatively charged cluster ions are recorded. We report, specifically, distributions of S m+, S m-, and C60S m- cont...

Third Sound and the Onset of Superfluidity in Unsaturated Helium Films

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