The Status of Cesium Beam Frequency Standards

There har been a lot ofprogress in cesium beam frequenq standards in the k t few years some of which will be reported here. Optical pumping is being pursued actively in u number of lahorufories. Optically slowed and cooled beums have been demonstrated as well as traps for cold neutral atoms. The microwuve cavity performance with regurd to hculphuse shgt at the beam hoks has been improved by use of carefully designed and built ring structuresfor the cavity ends. Work k being done on improvements in electronics with some emphasi,~ on use of digital circuitry and microprocessors. The frequenq pulling due to microwuve AM = f 1 trunsitions (Rumsey pulling) has been analyzed and shown to be important. Stdus of cesium beam frequency standards in some of the laboratories well as some of the commercial work will be discusuJ'~ed. Since much ofthe hboratory work going on invo1ve.s optical pumping und dettctwn, those items will get the most attention here.