Helium has always been a bit of an outsider on the Periodic Table. Its two isotopes, helium-3 and helium-4, remain liquid down to absolute zero and have the lowest liquefaction temperature among the gases. These features can be traced to the high zero-point energy relative to their attractive potential. In two dimensions, helium4 will form a liquid and become superfluid at temperatures that dep...

this article describes an accurate subpico flowmeter bifurcatedin to liquid and gas flowrates less than 1mol/s for both mems/nems and cryogenic technology applications. the mems/nems are described as either two gauges (instrument), or quartz fluctuating forks, even if the liquid or gas flows through an element, as well as cryogenic technology consisting of arrays of either parallel photonic cry...

This paper presents results pertaining to the numerical modeling of the cryogenic system at the Canadian Light Source. The cryogenic system consists of the cryostat that houses a Radio Frequency (RF) Cavity used for boosting energy of an electron beam. For consistent operation of the RF Cavity, it must be kept immersed in liquid helium at a constant level with the pressure in the gas space main...

Positively charged helium clusters, also called 'snowballs', have been investigated within normal liquid helium. Thermodynamic state equations for ionic helium clusters in liquid helium have been developed, allowing us to discern the 'hydrodynamic' radius for a wide range of hydrostatic pressures and temperatures. The mobilities derived from the cluster sizes using stokes law match experimental...

This paper presents results pertaining to the numerical modelling of the cryogenic system at the Canadian Light Source. The cryogenic system consists of a cryostat that houses a Radio Frequency (RF) cavity used for boosting the energy of an electron beam. For consistent operation of the RF cavity, it must be kept immersed in liquid helium at a constant level with the pressure in the gas space m...

Systematic studies of the phase and density dependence of the delayed annihilation time spectra of antiprotons (DATS) in gaseous, liquid and solid helium have been performed using the Low Energy Antiproton Ring (LEAR) at CERN. The results show a small but signiicant dependence of DATS on the phase and density of the helium medium. The average lifetime of antiprotons (T av) in gas at 10-30 K was...

We explore experimentally the fluidization of vertically agitated polymethylmethacrylate spheres wetted by liquid 4He . By controlling the temperature around the lambda point, we change the properties of the wetting liquid from a normal fluid (helium I) to a superfluid (helium II). For wetting by helium I, the critical acceleration for fluidization (Gamma_{c}) shows a steep increase close to th...

Helium droplets provide the possibility to study phenomena at the very low temperatures at which quantum mechanical effects are more pronounced and fewer quantum states have significant occupation probabilities. Understanding the migration of either positive or negative charges in liquid helium is essential to comprehend charge-induced processes in molecular systems embedded in helium droplets....

On the basis of electronic structure calculations, the structure of intrinsic positive charge solvated in superfluid helium is identified as triatomic He3(+) ion, which is bound to the surrounding ground state helium atoms through the charge–charge induced dipole interaction in a pairwise additive manner. Bosonic density functional theory calculations show that this ion forms the well-known Atk...