Loading a fountain clock with an enhanced low-velocity intense source of atoms

摘要

We present experimental work for improved atom loading in the optical molasses of a cesium fountain clock, employing a low-velocity intense source of atoms [Lu et al., Phys. Rev. Lett 77, 3331 (1996)], which we modify by adding a dark-state pump laser. With this modification the atom source has a mean flux of 4 x 10(8) atoms/s at a mean atom velocity of 8.6 m/s. Compared to fountain operation using background gas loading, we achieve a significant increase of the loaded and detected atom number by a factor of 40. Operating the fountain clock with a total number of detected atoms Nat = 2.9 x 10(6) in the quantum projection noise-limited regime, a frequency instability sy (1s) = 2.7 x 10(-14) is demonstrated.