A cesium fountain frequency standard: preliminary results

摘要: Laser cooling of atoms has opened up new possibilities in the field atomic frequency standards. A cesium fountain, first proposed by Zacharias 1953, is now feasible: atoms, cooled six laser beams, are launched upward using light, pass once through a microwave cavity, continue their ballistic flight and then fall same cavity. The long time between two interactions leads to Ramsey resonance much narrower than conventional Cs clocks thermal beams. stability accuracy such fountain very attractive. use diode lasers cool, launch detect low pressure cell allows construction simple reliable standard. standard operation at LPTF. as narrow 0.8 Hz been obtained. few days continuous routinely In closed loop continuously monitored against H maser allowing an evaluation device. short-term about 5.10/sup -13/ /spl tau//sup - 1/2 / limited only noise source. We intend present preliminary this with discussion major systematic effects which determine accuracy. expected be 10/sup -14/ level. addition, description whole design presented. >