Laser collimation of a continuous beam of cold atoms using Zeeman-shift degenerate-Raman-sideband cooling

In this article we report on the use of degenerate-Raman-sideband cooling for the collimation of a continuous beam of cold cesium atoms in a fountain geometry. Thanks to this powerful cooling technique we have reduced the atomic beam transverse temperature from 60 μK to 1.6 μK in a few milliseconds. The longitudinal temperature of 80 μK is not modified. The flux density, measured after a parabolic flight of 0.57 s, has been increased by a factor of 4 to approximately 107 at. s⁻¹ cm⁻² and we have identified a Sisyphus-like precooling mechanism which should make it possible to increase this flux density by an order of magnitude.