2018/09/10 by S. Weyers, V. Gerginov, Vladislav Gerginov +9 · 1 citation
Decision Sciences · Mathematics · Physics and Astronomy · #Advanced Frequency and Time Standards #Atomic and Subatomic Physics Research #Atomic clock #Caesium #Fountain #Frequency standard #Local oscillator #Mathematics #Microwave #Nuclear physics #Optics #Phase noise #Physics #Quantum mechanics #Realization (probability) #Reliability (semiconductor) #Scientific Measurement and Uncertainty Evaluation #Statistics #physics.atom-ph
paper · pdf · doi:10.1088/1681-7575/aae008
published as Metrologia 55, 789 (2018) · 33 pages, 7 figures
arxiv created 2018/09/10 · openalex publication_date 2018/09/10 · openalex created_date 2018/09/27 · arxiv updated 2018/10/22 · openalex updated_date 2026/08/05
Abstract Improvements of the systematic uncertainty, frequency instability, and long-term reliability of the two caesium fountain primary frequency standards CSF1 and CSF2 at PTB (Physikalisch-Technische Bundesanstalt) are described. We have further investigated many of the systematic effects and made a number of modifications of the fountains. With an optically stabilized microwave oscillator, the quantum projection noise limited frequency instabilities are improved to for CSF1 and for CSF2 at high atom density. The systematic uncertainties of CSF1 and CSF2 are reduced to and , respectively. Both fountain clocks regularly calibrate the scale unit of International Atomic Time (TAI) and the local realization of Coordinated Universal Time, UTC(PTB), and serve as references to measure the frequencies of local and remote optical frequency standards.