# Improved accuracy of the NPL-CsF2 primary frequency standard: evaluation of distributed cavity phase and microwave lensing frequency shifts

@article{Li2011ImprovedAO, title={Improved accuracy of the NPL-CsF2 primary frequency standard: evaluation of distributed cavity phase and microwave lensing frequency shifts}, author={Ruoxin Li and K. Gibble and K. Szymaniec}, journal={Metrologia}, year={2011}, volume={48}, pages={283-289} }

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… Expand

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#### References

SHOWING 1-10 OF 14 REFERENCES

First accuracy evaluation of the NPL-CsF2 primary frequency standard

- Physics
- 2010

An accuracy evaluation of the caesium fountain NPL-CsF2 as a primary frequency standard is reported. The device operates with a simple one-stage magneto-optical trap as the source of cold atoms. Both… Expand

Evaluating and minimizing distributed cavity phase errors in atomic clocks

- Physics
- 2010

We perform 3D finite element calculations of the fields in microwave cavities and analyse the distributed cavity phase (DCP) errors of atomic clocks that they produce. The fields of cylindrical… Expand

Phase variations in microwave cavities for atomic clocks

- Physics
- 2004

We analyse the phase variations of the microwave field in a TE011 microwave cavity and how these variations affect the frequency of an atomic clock. We analytically solve for the microwave fields in… Expand

Recoil Effects in Microwave Ramsey Spectroscopy

- Physics
- 2004

We present a theory of recoil effects in two zone Ramsey spectroscopy, particularly adapted to microwave frequency standards using laser cooled atoms. We describe the atoms by a statistical… Expand

Evaluation of the primary frequency standard NPL-CsF1

- Physics
- 2005

A new caesium fountain frequency standard (NPL-CsF1) at the National Physical Laboratory is described. Procedures for evaluation of the systematic frequency shifts are presented. The NPL-CsF1 has a… Expand

Evaluation of Doppler shifts to improve the accuracy of primary atomic fountain clocks.

- Physics, Medicine
- Physical review letters
- 2011

Experimental verification of the finite element models of the cavities gives the first quantitative evaluation of this leading uncertainty and allows it to be reduced to δν/ν=±8.4×10(-17). Expand

Primary Frequency Standard NPL-CsF2: Optimized Operation Near the Collisional Shift Cancellation Point

- Physics, Computer Science
- IEEE Transactions on Instrumentation and Measurement
- 2011

An additional optical pumping stage has been implemented and the number of detected atoms is increased by a factor of four, which has led to a fourfold reduction in averaging time required to achieve a given statistical resolution, e.g., that matches the type-B uncertainty of NPL-CsF2. Expand

Power dependence of the frequency bias caused by spurious components in the microwave spectrum in atomic fountains

- Physics, Medicine
- IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
- 2006

It is, at best, difficult to use elevated power microwaves in fountain frequency standards to test for the presence of spurs in the microwave spectrum, because of the extremely rich and unintuitive behavior of these frequency shifts. Expand

Apparent Power-Dependent Frequency Shift Due to Collisions in a Cesium Fountain

- Physics, Medicine
- IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
- 2007

A situation where a varying collisional frequency shift in cesium fountain primary frequency standards can be misinterpreted as a power-dependent shift may affect analyses of fountains test-operated at multiple pi/2 microwave pulse areas. Expand

Cooling in an optical lattice for a caesium fountain frequency standard

- Materials Science, Computer Science
- IEEE Transactions on Instrumentation and Measurement
- 2005

Progress toward a Cs-fountain frequency standard operating in the nanokelvin temperature range is reported, and the Raman sideband cooling in a far-off-resonance optical lattice is implemented and observed subrecoil temperatures of 200 nK. Expand