Bright, slow, and continuous beam of laser-cooled cesium atoms

By the moving molasses technique we have extracted laser-cooled cesium atoms in a continuous way directly from an optical molasses. The mean launching velocity is precisely tunable from 1 to 12 m/s. The atomic beam has a flux of 1.3×10⁸ atom/s at 7 m/s and a longitudinal temperature of 70 μK, which represents the highest flux and lowest velocity spread obtained so far in a continuous beam of cold atoms. These features makes it well suited for atomic fountains. The atomic flux can be slightly increased in a two-dimensional magneto-optical trap operation $(+40%).$ A simple model accounts for the observed dependence of the flux with the magnetic-field gradient.