TY - JOUR
T1 - Improved accuracy of the NPL-CsF2 primary frequency standard
T2 - Evaluation of distributed cavity phase and microwave lensing frequency shifts
AU - Li, Ruoxin
AU - Gibble, Kurt
AU - Szymaniec, Krzysztof
PY - 2011
Y1 - 2011
N2 - We evaluate the distributed cavity phase (DCP) and microwave lensing frequency shifts, which were the two largest sources of uncertainty for the NPL-CsF2 caesium fountain clock. We report measurements that confirm a detailed theoretical model of the microwave cavity fields and the frequency shifts of the clock that they produce. The model and measurements significantly reduce the DCP uncertainty to 1.1 × 10-16. We derive the microwave lensing frequency shift for a cylindrical cavity with circular apertures. An analytic result with reasonable approximations is given, in addition to a full calculation that indicates a shift of 6.2 × 10-17. The measurements and theoretical models we report, along with improved evaluations of collisional and microwave leakage induced frequency shifts, reduce the frequency uncertainty of the NPL-CsF2 standard to 2.3 × 10-16, nearly a factor of two lower than its most recent complete evaluation.
AB - We evaluate the distributed cavity phase (DCP) and microwave lensing frequency shifts, which were the two largest sources of uncertainty for the NPL-CsF2 caesium fountain clock. We report measurements that confirm a detailed theoretical model of the microwave cavity fields and the frequency shifts of the clock that they produce. The model and measurements significantly reduce the DCP uncertainty to 1.1 × 10-16. We derive the microwave lensing frequency shift for a cylindrical cavity with circular apertures. An analytic result with reasonable approximations is given, in addition to a full calculation that indicates a shift of 6.2 × 10-17. The measurements and theoretical models we report, along with improved evaluations of collisional and microwave leakage induced frequency shifts, reduce the frequency uncertainty of the NPL-CsF2 standard to 2.3 × 10-16, nearly a factor of two lower than its most recent complete evaluation.
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U2 - 10.1088/0026-1394/48/5/007
DO - 10.1088/0026-1394/48/5/007
M3 - Article
AN - SCOPUS:80053177118
SN - 0026-1394
VL - 48
SP - 283
EP - 289
JO - Metrologia
JF - Metrologia
IS - 5
M1 - 007
ER -