Systematic shifts in the frequency of NPLI-CsF1

At CSIR-National Physical Laboratory, India (NPLI) we have developed first generation of Cesium atomic fountain (NPLI-CsF1) primary frequency standard (PFS). NPLI-CsF1 is now fully operational and its frequency is now being evaluated along with all systematic and statistical uncertainties. The present experimental data conforms that fountain frequency is stable to few parts in 1015 at less than one day averaging time. The fountain frequency is compared with the Hydrogen MASER (H-MASER) which is contributing to TAI already and hence fountain frequency is traceable to TAI. Recent evaluation results were communicated to BIPM and published in circular T. Typical stability of NPLI CsF1 is ∼7 × 10⁻¹³ τ^−1/2. The present performance of fountain is limited by the measurement uncertainty of cold collisional shift.