Helium facility

The ultracold metastable helium facility

Applying laser cooling and trapping at a wavelength of 1083 nm an ultracold gas a helium atoms in a metastable state is produced at a temperature of 1 mK. About a billion atoms are trapped in a magneto-optical trap and, in one of the two experimental setups, are further cooled by forced evaporative cooling to a temperature of 1 microkelvin. Both helium isotopes can be cooled allowing experiments near the quantum degenertae regime, where Bose-Einstein Condensation of helium-4 can be studied and a Degenerate Fermi Gas of helium-3.
The figures below show the trapping schematically.

 trap2nature trap

   
The atoms are trapped in a cloverleaf magnetic trap and can be studied releassing them from the trap and detection by time-of-flight to a microchannel plate detector (right figure) or by absorption imaging.
This system has been used in a very fruitfull LASERLAB-ACCESS project to study the Hanbury Brown Twiss effect with ultracold bosons and fermions. Details can be found here.
Contact Person at LaserLaB: Wim Vassen, email: w.vassen@vu.nl