Title :
Initial evaluation of the NPL caesium fountain frequency standard
Author :
Szymaniec, K. ; Chalupczak, W. ; Henderson, D.
Author_Institution :
Nat. Phys. Lab., Teddington, UK
Abstract :
An initial performance evaluation of the caesium fountain primary frequency standard at the NPL is reported. Improved magnetic shielding has resulted in the inhomogeneity of the C-field being below 1 nT and has enabled the observation of full-contrast Ramsey fringes. A direct evaluation of the fountain´s stability in comparison to a hydrogen maser is shown to agree with the short-term stability inferred from the signal-to-noise ratio. The stability is consistent with the limit set by the local oscillator. The measurement of the frequency bias due to cold collisions is described, together with the associated uncertainty.
Keywords :
Zeeman effect; atomic clocks; atomic collisions; caesium; frequency stability; frequency standards; magnetic shielding; measurement uncertainty; C-field inhomogeneity; Cs; NPL caesium fountain frequency standard; Ramsey fringe; cold collision; fountain stability; frequency bias measurement; magnetic shielding; performance evaluation; signal-noise ratio; uncertainty evaluation; Atom optics; Atomic beams; Atomic measurements; Frequency; Laser beams; Laser excitation; Magnetic noise; Masers; Phase noise; Solenoids;
Conference_Titel :
Frequency Control Symposium and PDA Exhibition Jointly with the 17th European Frequency and Time Forum, 2003. Proceedings of the 2003 IEEE International
Print_ISBN :
0-7803-7688-9
DOI :
10.1109/FREQ.2003.1274998
