Systematic shift uncertainty evaluation of IEN CSF1 primary frequency standard

We report a preliminary systematic shift uncertainty evaluation of our cesium fountain and of the first comparison with the NIST-F1 clock of the National Institute of Standard and Technology (NIST) with a two way satellite comparison system. The stability of the time scale UTC (IEN), (generated with a commercial Cs beam) is insufficient to allow evaluation of systematic shifts by conventional techniques; therefore, the accuracy evaluation of the fountain was accomplished using mainly fast differential techniques, resulting in an overall uncertainty of 3×10^-15.