Bose-Einstein condensation in a gas of sodium atoms

We have observed Bose-Einstein condensation of sodium atoms. The atoms were trapped in a novel trap that employed both magnetic and optical forces. Evaporative cooling increased the phase-space density by 6 orders of magnitude within seven seconds. Condensates contained up to 5 x 105 atoms at densities exceeding 1014 cm-3. The striking signature of Bose condensation was the sudden appearance of a bimodal velocity distribution below the critical temperature of ~2µK. The distribution consisted of an isotropic thermal distribution and an elliptical core attributed to the expansion of a dense condensate.