title: Large atom number Bose-Einstein condensate of sodium.
abstract: We describe the setup to create a large Bose-Einstein condensate containing more than 120 x 10(6) atoms. In the experiment a thermal beam is slowed by a Zeeman slower and captured in a dark-spot magneto-optical trap (MOT). A typical dark-spot MOT in our experiments contains 2.0 x 10(10) atoms with a temperature of 320 microK and a density of about 1.0 x 10(11) atoms/cm(3). The sample is spin polarized in a high magnetic field before the atoms are loaded in the magnetic trap. Spin polarizing in a high magnetic field results in an increase in the transfer efficiency by a factor of 2 compared to experiments without spin polarizing. In the magnetic trap the cloud is cooled to degeneracy in 50 s by evaporative cooling. To suppress the three-body losses at the end of the evaporation, the magnetic trap is decompressed in the axial direction.
authors.affiliation: Atom Optics and Ultrafast Dynamics, Utrecht University, TA Utrecht, The Netherlands.
authors.forename: K M R
authors.initials: KM
authors.lastname: van der Stam
authors.forename: E D
authors.initials: ED
authors.lastname: van Ooijen
authors.forename: R
authors.initials: R
authors.lastname: Meppelink
authors.forename: J M
authors.initials: JM
authors.lastname: Vogels
authors.forename: P
authors.initials: P
authors.lastname: van der Straten
mesh_terms: D008280:Magnetics / Q000295:instrumentation; D055095:Optics and Photonics / Q000295:instrumentation; D012964:Sodium / Q000737:chemistry*; D019097:Spin Trapping / Q000295:instrumentation / Q000379:methods
chemical_list: D012964:Sodium