Quantitative evaluation of distributed cavity phase shifts to improve the accuracy of SYRTE FO2

We report measurements and ab initio calculations of the distributed cavity phase (DCP) shifts of the LNE-SYRTE FO2 atomic fountain clock. The measurements and validated model provide the first complete and quantitative evaluation of the DCP shift in an atomic fountain, reducing the FO2 DCP uncertainty to ±8.4×10
^-17
. Here we emphasize the experimental techniques that precisely determine the fountain parameters to stringently test the DCP model.