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We present an improved model relating the frequency shift between 133Cs hyperfine Zeeman substates to the Lorentz-violating coefficients of the Standard-Model Extension (SME) framework. This model is based on a second order boost Lorentz transformation, which enables us to constrain the isotropic coefficient CTT. It also takes into account the nuclear structure, beyond the usual Schmidt model, extending...
The ACES (atomic clock ensemble in space) mission is an ESA - CNES project with the aim of setting up onboard the international space station (ISS) several highly stable atomic clocks with a microwave communication link (MWL). The specifications of the MWL are to perform ground to space time and frequency comparisons with a stability of 0.3 ps at one ISS pass and 7 ps at one day. The ACES mission...
We report on measurements to characterize phase gradients inside the Cs microwave cavity in the SYRTE double fountain FO2. The clock frequency is measured as a function of the tilt of launch velocity with respect to gravity, as a function of the microwave power and when feeding the Ramsey cavity from either sides or symmetrically using the two microwave feedthroughs. These measurements are made with...
We report on a new experiment that tests for a violation of Lorentz invariance (LI), by searching for a dependence of atomic transition frequencies on the orientation of the spin of the involved states (Hughes-Drever type experiment). The atomic frequencies are measured using a laser cooled 133Cs atomic fountain clock, operating on a particular combination of Zeeman substates. We analyze the results...
Over the last few years the number of high accuracy (uncertainties in the low 10−15 or less) primary frequency standards contributing to TAI has increased significantly from only two over the period 2000 – 2002 to seven over the period 2002 – 2005. As a consequence the number of individual measurements of TAI frequency by such standards over the period 1999 to 2005 is > 60 and increasing rapidly...
For a long time, one of the main limitations of cesium atomic fountains has been the cold collision frequency shift [2, 7, 10, 11]. By using a method based on a transfer of population by adiabatic passage (AP) [12, 16, 18] allowing to prepare cold atomic samples with a well defined ratio of atomic density as well as atom number we have a better measurement of this effect. By improving the method we...
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