Development of a MOT-based continuous cold Cs-beam atomic clock

Summary form only given. We discuss our compact clock physics package and report the realization of a continuous, cold Cs atomic beam from a vapor-cell magneto-optical trap (MOT) of Cs atoms. Briefly, we generate the cold Cs beam by perturbing the trap potentials with a small opaque disk inserted in one of the MOT beams. Along the narrow dark column thus formed, Cs atoms are continuously accelerated out of the trap volume to form a Cs beam while the MOT remains in functioning of capturing and cooling Cs atoms from the Cs vapor. The fluorescence image of the Cs trap and the continuous Cs atomic beam are shown. Our MOT captures and confines 8 /spl times/ 10/sup 7/ Cs atoms at a loading rate of 2 /spl times/ 10/sup 8/ atoms/s and cools the atoms to a thermal temperature of 300 /spl mu/K. The longitudinal velocity of the cold Cs beam is measured by a time of flight (TOF) method. A single-shot laser-induced fluorescence signal recorded at a distance of 18 cm downstream from the MOT is shown. Under the nominal experimental conditions, the TOF measurement determines that our cold Cs atomic beam travels at 7 m/s and has a velocity spread of 0.9 m/s. With the cold Cs beam thus formed and a compact Ramsey cavity of 20 cm in length, we have estimated a short-term Allan deviation of 1.8 /spl times/ 10/sup -13/ /spl tau//sup -1/2/ (T is the averaging time) for the atomic clock under development.