Evaporative Cooling of He* in the multi-partial-wave regime
We
have buffer gas cooled, magnetically trapped, and evaporatively
cooled metastable helium in large numbers. 10 ^11 4He*
atoms are trapped at an initial temperature of 400 mK
and evaporatively cooled into the ultracold regime,
resulting in a cloud of 2x10 9 atoms at 1.4 mK. This
results marks three significant feats. First, the number
obtained at 1.4 mK is larger than that attained via
laser cooling, and with much room for improvement. Second,
evaporation was performed well in the multi-partial-wave
regime and was efficient all the way into the ultracold
regime, indicating low collisional loss in agreement
with theory. And third, this is an increase of 5 orders
of magnitude in phase space density from the initial
loading conditions, the first time a significant increase
in phase space density for a buffer gas loaded sample
has been achieved. The results hold tremendous promise
for achieving large quantum degenerate gases in the
fully hydrodynamic regime and for prospects for sympathetically
cooling polar molecules into the ultracold regime.
For more information:
Detailed description
Paper
Poster
- Extend ultracold physics to new atomic and molecular species.
- Study collisional properties of atoms and molecules in the ultracold and multi-partial-wave regime.
- Produce and study quantum degenerate gases of >
10 ^10 atoms in the fully hydrodynamic regime
- Study strongly correlated many and few body physics with dipolar gases of atoms and molecules.
For more information see: Buffer gas loading vision and proposal.
- Production via both cryogenic rf-discharge and laser ablation
- No laser cooling - entirely evaporative
- Forced evaporation via absorption onto a cryogenic surface
- Ability to simultaneously trap other atoms and molecules
- Rapid removal of buffer gas via a new, cryogenic valve
- 4.2 Tesla deep Anti-Helmholtz superconducting magnetic trap
More about
Buffer Gas Loading 
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