Caesium standard - Wikipedia
The caesium standard is a primary frequency standard in which the photon absorption by transitions between the two hyperfine ground states of caesium-133 atoms is used to control the output frequency.
NIST’s Cesium Fountain Atomic Clocks
2009年8月26日 · The nation's primary frequency standard is a cesium fountain atomic clock developed at the NIST laboratories in Boulder, Colorado. A primary frequency standard contributes to the calibration of the official international time scale Coordinated Universal Time (UTC), and to its local realization UTC(NIST) which is synthesized and distributed from ...
Atomic clock - Wikipedia
The primary standard for the United States, the National Institute of Standards and Technology (NIST)'s caesium fountain clock named NIST-F2, measures time with an uncertainty of 1 second in 300 million years (relative uncertainty 10 −16). NIST-F2 was brought online on 3 April 2014.
Caesium - Wikipedia
The caesium standard is the primary standard for standards-compliant time and frequency measurements. [84] Caesium clocks regulate the timing of cell phone networks and the Internet. [85]
Caesium: A brief history of timekeeping - BBC News
2014年10月3日 · Caesium is the chemical element that has literally redefined time. It keeps time so accurately that it has even forced us to reconsider what time is.
A Walk Through Time - The "Atomic Age" of Time Standards
2009年8月12日 · As of January, 2002, NIST's latest primary cesium standard was capable of keeping time to about 30 billionths of a second per year. Called NIST-F1, it is the 8th of a series of cesium clocks built by NIST and NIST's first to operate on the "fountain" principle.
A Brief Notes To Time/Frequency Standards - An Introduction
Cesium (caesium) Standard: The cesium standard is the primary standard of time/frequency. It is the standard maintained by over 250+ atomic stations around the world for keeping the UTC.
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