title: High-accuracy measurement of the blackbody radiation frequency shift of the ground-state hyperfine transition in 133Cs.
abstract: We report a high-accuracy direct measurement of the blackbody radiation shift of the 133Cs ground-state hyperfine transition. This frequency shift is one of the largest systematic frequency biases encountered in realizing the current definition of the International System of Units (SI) second. Uncertainty in the blackbody radiation frequency shift correction has led to its being the focus of intense theoretical effort by a variety of research groups. Our experimental measurement of the shift used three primary frequency standards operating at different temperatures. We achieved an uncertainty a factor of five smaller than the previous best direct measurement. These results tend to validate the claimed accuracy of the recently calculated values.
authors.affiliation: NIST-Time and Frequency Division, 325 Broadway Div 688 Boulder, Colorado 80305, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Jefferts
authors.affiliation: NIST-Time and Frequency Division, 325 Broadway Div 688 Boulder, Colorado 80305, USA.
authors.forename: T P
authors.initials: TP
authors.lastname: Heavner
authors.affiliation: NIST-Time and Frequency Division, 325 Broadway Div 688 Boulder, Colorado 80305, USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Parker
authors.affiliation: NIST-Time and Frequency Division, 325 Broadway Div 688 Boulder, Colorado 80305, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Shirley
authors.affiliation: NIST-Time and Frequency Division, 325 Broadway Div 688 Boulder, Colorado 80305, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Donley
authors.affiliation: NIST-Time and Frequency Division, 325 Broadway Div 688 Boulder, Colorado 80305, USA.
authors.forename: N
authors.initials: N
authors.lastname: Ashby
authors.affiliation: INRIM, Str della Cacce, 91 10135 Torino, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Levi
authors.affiliation: INRIM, Str della Cacce, 91 10135 Torino, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Calonico
authors.affiliation: Politecnico di Torino, C. Duca degli Abruzzi, 24 10129 Torino, Italy.
authors.forename: G A
authors.initials: GA
authors.lastname: Costanzo