Calibration of International Atomic Time by the Optically Pumped Cesium Frequency Standard

Abstract

The optically pumped cesium (Cs) frequency standard at NRLM (NRLM-4) was developed. We determined the frequency stability by comparing the phase with that of a hydrogen maser: the Allan deviation was σ_y(τ)=5×10^-13/√τ. We estimated the frequency corrections and uncertainties due to various sources, and the total uncertainty was found to be 2.9×10^-14. The frequency difference between NRLM-4 and the international atomic time (TAI) was also measured.