https://doi.org/10.1007/s100530050572
Buffer-gas loaded magnetic traps for atoms and molecules: A primer
1
Department of Physics,
Harvard University, Cambridge, MA 02138, USA
2
Department of Chemistry and Chemical Biology, Harvard
University, Cambridge, MA 02138, USA
Received:
2
November
1998
Revised:
19
February
1999
Published online: 15 October 1999
Over the past three years we have developed the technique of buffer-gas
cooling and loading of atoms and molecules into magnetic traps. Buffer-gas
cooling relies solely on elastic collisions (thermalization) of the
species-to-be-trapped with a cryogenically cooled helium gas and so is
independent of any particular energy level pattern. This makes the cooling
technique general and potentially applicable to any species trappable at the
temperature of the buffer gas (as low as ). Using
buffer-gas loading, paramagnetic atoms (europium and chromium) as well as a
molecule (calcium monohydride) were trapped at temperatures around 300 mK.
The numbers of the trapped atoms and molecules were respectively about
1012 and 108. The atoms and molecules were produced by laser
ablation of suitable solid precursors. In conjunction with evaporative
cooling, buffer-gas loaded magnetic traps offer the means to further lower
the temperature and increase the density of the trapped ensemble to study a
large variety of both static (spectra) and dynamic (collisional
cross-sections) properties of many atoms and molecules at ultra-low temperatures.
In this article we survey our main results obtained on Cr, Eu, and CaH and
outline prospects for future work.
PACS: 32.80.Pj – Optical cooling of atoms; trapping / 06.30.Ft – Time and frequency / 32.30.Jc – Visible and ultraviolet spectra
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999