Bertrand Boussert, Gaëlle Lucas-Leclin, Frédéric Hamouda, Pierre Cérez, and Geneviéve Théobald
ABSTRACT The optically pumped cesium beam clock named Cs~IV is operated with a new short Ramsey cavity satisfying strict requirements on the microwave leakage level. The most relevant characteristics of the device are presented. Cs IV is presently driven by standard electronics coming from a HP 5061 B clock that provides a sinusoidal modulation of the interrogation microwave signal and a microwave power stability of about 1% at a temperature of 20 ± 1°C. The short- and medium-term frequency stability measurement gives Sigmay 1 day) = 2 x 10-14: this value holds up to 3 days. The accuracy evaluation results in an uncertainty of 10-12, and the repeatability is evaluated to 3 x 10-13. It appears that the flicker floor is beginning at 2 x 10-14 and is mainly due to both the power fluctuations of the free running microwave interrogating signal and the fluctuations of the external static magnetic field. The accuracy is limited by the lack of knowledge of the end-to-end cavity phase shift.
1999 IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control Vol. 46, pp. 366-371, 1999
© 1999, by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.