Laser-cooled cesium atomic fountain experiment for atomic frequency standard

A cesium frequency standard based on the atomic fountain configuration has the potential of improving the accuracy of primary frequency standard. For the first step toward a realization of slow vertical atomic beam (that is an atomic fountain), we have succeeded to decelerate the horizontal cesium atomic beam by laser cooling with the Zeeman tuning method. Then those slowed atoms are confined with a magneto-optical trap by four laser beams in the tetrahedral configuration. By using these trapped atoms, one can launch them upward with the upstream laser pulses