title: Microwave leakage-induced frequency shifts in the primary frequency standards NIST-F1 and IEN-CSF1.
abstract: In atomic fountain primary frequency standards, the atoms ideally are subjected to microwave fields resonant with the ground-state, hyperfine splitting only during the two pulses of Ramsey's separated oscillatory field measurement scheme. As a practical matter, however, stray microwave fields can be present that shift the frequency of the central Ramsey fringe and, therefore, adversely affect the accuracy of the standard. We investigate these uncontrolled stray fields here and show that the frequency errors can be measured, and indeed even the location within the standard determined by the behavior of the measured frequency with respect to microwave power in the Ramsey cavity. Experimental results that agree with the theory are presented as well.
authors.affiliation: NIST, Time and Frequency Division, Boulder, CO 80305, USA.
authors.forename: Jon H
authors.initials: JH
authors.lastname: Shirley
authors.forename: Filippo
authors.initials: F
authors.lastname: Levi
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Heavner
authors.forename: Davide
authors.initials: D
authors.lastname: Calonico
authors.forename: Dai-Hyuk
authors.initials: DH
authors.lastname: Yu
authors.forename: Steve R
authors.initials: SR
authors.lastname: Jefferts
mesh_terms: D003198:Computer Simulation; D017408:Guidelines as Topic; D038622:Internationality; D008872:Microwaves; D008956:Models, Chemical; D011846:Radio Waves; D012015:Reference Standards; D013997:Time Factors; D014732:Vibration