Cesium Fountain Primary Frequency Standard NMIJ-F2 with Uncertainty Evaluated

We completed the first uncertainty evaluation of NMIJ-F2, the second cesium fountain primary frequency standard at National Metrology Institute of Japan. The type A uncertainty was given as 2.3 × 10
⁻¹³
(τ/s)
^−1/2
(τ: averaging time), and the total type B uncertainty was 4.6 × 10
⁻¹⁶
. In addition, we started contribution to the calibration of International Atomic Time. The frequency of NMIJ-F2 agreed well with that of the other primary and secondary frequency standards within the uncertainty.