Preliminary accuracy evaluation of a cesium fountain primary frequency standard at NIST

Since November of 1998, we have performed four uncertainty evaluations on NIST F-1, our laser-cooled cesium fountain. The results from the latest evaluation have a statistical uncertainty of 2.6/spl times/10/sup -15/ and an uncorrected bias of 1.1/spl times/10/sup -15/. This paper presents a brief overview of the evaluations and their uncertainties.

[1]  M. Bahoura,et al.  The LPTF preliminary accuracy evaluation of cesium fountain frequency standard , 1996 .

[2]  Jon H. Shirley,et al.  Some Causes of Resonant Frequency Shifts in Atomic Beam Machines. I. Shifts Due to Other Frequencies of Excitation , 1963 .

[3]  Leo W. Hollberg,et al.  NIST caesium fountain frequency standard: preliminary results , 1998, Proceedings of the 1998 IEEE International Frequency Control Symposium (Cat. No.98CH36165).

[4]  T. Parker,et al.  Hydrogen maser ensemble performance and characterization of frequency standards , 1999, Proceedings of the 1999 Joint Meeting of the European Frequency and Time Forum and the IEEE International Frequency Control Symposium (Cat. No.99CH36313).

[5]  A. DeMarchi,et al.  NIST cesium fountain microwave cavities , 1998, Proceedings of the 1998 IEEE International Frequency Control Symposium (Cat. No.98CH36165).

[6]  A. Clairon,et al.  AN EXPERIMENTAL STUDY OF THE SPIN-EXCHANGE FREQUENCY SHIFT IN A LASER-COOLED CESIUM FOUNTAIN FREQUENCY STANDARD , 1996 .