The atomichron ® - An atomic frequency standard: Operation and performance

The successful design of a self-contained, sealed-off atomic beam tube in which cesium exhibits its resonance properties, has led to the development of a frequency generating system which provides an accuracy of 1 part in 10⁹and a stability of better than 5 parts in 10¹⁰for the lifetime of the equipment. The system consists of a beam tube which resonates at 9192.631840 mc, a frequency source which generates an RF field at the resonance frequency to drive the beam tube, and a control loop for automatic correction of this source. Operation and features of the frequency standard are described, including photographs and recordings.