Development of a cesium atomic fountain frequency standard

We report on the development of a cesium atomic fountain frequency standard at the Korea Research Institute of Standards and Science (KRISS). Cesium atoms were launched upwards by using an optical moving molasses method after they were cooled in a magnetooptical trap. The temperature of launched atoms was about 2.5 (mu)K. From our cesium atomic fountain, we were able to observe Ramsey fringes of 1-Hz linewidth on the 9.2-GHz clock transition of cesium atoms.