Very long storage times and evaporative cooling of cesium atoms in a quasielectrostatic dipole trap - art. no. 031402

We have trapped cesium atoms over many minutes in the focus of a CO2-laser beam employing an extremely simple laser system. Collisional properties of the unpolarized atoms in their electronic ground state are investigated. In elastic binary collisions changing the hyperfine state lead to trap loss, w hich is quantitatively analyzed. Elastic collisions result in evaporative c ooling of the trapped gas from 25 mu K to 10 mu K over a time scale of abou t 150 s.