Observation of Bose-Einstein condensation in atomic hydrogen by laser spectroscopy

Summary form only given. Atomic hydrogen is the newest member of the small family of atomic gases that display Bose-Einstein condensation (BEC). The conditions are quite different from those of the alkali metal atom condensates, for the gas condenses at a temperature of 40 microkelvin, rather than in the nanokelvin regime. The atoms are initially trapped using cryogenic methods and is then cooled to BEC by evaporation. More than 10/sup 9/ atoms were trapped in the initial experiments, larger than previous condensates by a factor of thirty. The condensate is studied primarily by two-photon laser spectroscopy on the 1S-2S transition. Both Doppler-free and Doppler-sensitive transitions are visible. The spectral response of the condensate displays some unexpected properties.