Operation of the NIST-F1 caesium fountain primary frequency standard with a maser ensemble, including the impact of frequency transfer noise

Abstract

The operation of a caesium fountain primary frequency standard is greatly influenced by the characteristics of two other important facilities. The first is a stable frequency reference and the second is the frequency-transfer system. A stable frequency reference such as a hydrogen maser is a virtual necessity since essentially no fountain dead time can be tolerated without it. The frequency stability of this reference has a significant impact on the procedures for evaluating certain systematic biases in the fountain. State-of-the-art frequency transfer technology is also necessary if the fountain is intended to contribute to TAI or to be compared with other remotely located frequency standards without excessive degradation of stated uncertainties. We discuss the facilities available at the National Institute of Standards and Technology (NIST) and how they impact the operation of NIST-F1, the primary frequency standard at NIST.