EVAPORATIVE COOLING OF ATOMIC-HYDROGEN - THEORY OF COOLING AND PROGRESS TOWARDS THE BOSE-EINSTEIN TRANSITION

We present a model for and the results of experiments on evaporative c ooling of magnetically trapped atomic hydrogen. Forced evaporative coo ling and compression were performed simultaneously to produce a sample with a density of 8 x 10(13) cm-3 at a temperature of 100 muK, a fact or of 3.5 above the critical temperature of the Bose-Einstein condensa tion phase transition at this density and well below the 1.3 mK recoil limit for laser cooling. A quantitative model of evaporative cooling has been developed and its predictions are in good agreement with the data.