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The first caesium clock was built by Louis Essen in 1955 at the National Physical Laboratory in the UK [1] and promoted worldwide by Gernot M. R. Winkler of the United States Naval Observatory. Caesium atomic clocks are one of the most accurate time and frequency standards, and serve as the primary standard for the definition of the second in ...
The first in-house accuracy evaluation of NIST-F2 reported a u B of 1.1 × 10 −16. [5] In March 2014 and March 2015 the NIST-F2 cesium fountain clock reported a u B of 1.5 × 10 −16 in the BIPM reports of evaluation of primary frequency standards. The last submission of NIST-F1 to BIPM TAI was February 2016. [6]
Representations of the second other than the SI cesium standard are motivated by the increasing accuracy of other atomic clocks. In particular the high frequencies and small linewidths of optical clocks promise significantly improved signal-to-noise ratio and instability.
The evaluated accuracy u B reports of various primary frequency and time standards are published online by the International Bureau of Weights and Measures (BIPM). In May 2013 the NIST-F1 cesium fountain clock reported a u B of 3.1 × 10 −16. However, that BIPM report and the other recent reports are based on an evaluation that dates to 2005. [4]
Accuracy Location Image CS1 [1 ... 18 cesium atomic clocks and 4 hydrogen maser clocks Cs, H ... SOC: Space Optical Clock breadboard (Sr lattice clock) [29] Sr lattice
Optical cesium atomic clocks - Oscilloquartz has developed optical cesium atomic clocks that are more stable and accurate than magnetic cesium-based solutions and exceed the current ITU-T G.811.1 enhanced primary reference clock (ePRC) specification. The current highest-end clocks in this range combine with core grandmaster devices to provide ...
The majority of the clocks involved are caesium clocks; the International System of Units (SI) definition of the second is based on caesium. [6] The clocks are compared using GPS signals and two-way satellite time and frequency transfer. [7] Due to the signal averaging TAI is an order of magnitude more stable than its best constituent clock.
In 1967, his cesium "flying clock" was used in flights around the world to bring timekeeping accuracy down to about 0.1 microseconds. In 1972 and 1976, these same clocks were used in flight tests verifying Albert Einstein's theories of special and general relativity , [ 4 ] showing that time does slow down the faster you move or the closer you ...