{"paper":{"title":"Advances in the accuracy, stability, and reliability of the PTB primary fountain clocks","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"physics.atom-ph","authors_text":"B. Lipphardt (1), Braunschweig, G. Dobrev (1), Germany (2) The Pennsylvania State University, J. Rahm (1), K. Gibble (2) ((1) Physikalisch-Technische Bundesanstalt (PTB), M. Kazda (1), S. Weyers (1), University Park, USA), V. Gerginov (1)","submitted_at":"2018-09-10T14:44:24Z","abstract_excerpt":"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 $7.2 \\times 10^{-14} (\\tau/1\\,\\mathrm{s})^{-1/2}$ for CSF1 and $2.5 \\times 10^{-14} (\\tau/1\\,\\mathrm{s})^{-1/2}$ for CSF2 at high atom"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1809.03362","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}