NIST-F2 is the most accurate clock ever made

Date:14 August 2014 Tags:, , ,

America’s new top clock will gain or lose just 1 second over the next 300 million years. NIST-F2, built by the US National Institute of Standards and Technology in Boulder, Colorado, came online on 3 April.

Infrared laser beams aimed at a ball of caesium gascoax it into a fountain-like trajectory. As the atoms fall, they absorb and then re-emit bursts of radiation, at an unvarying frequency of 9 192 631 770 Hz. That frequency is the international definition of a second. So, the F2 doesn’t mark time – it defines what time is by establishing how long a second is, and it can be used to precisely calibrate clocks.

The new clock is three times as accurate as the old NIST-F1. And whereas the earlier model was kept at room temperature, NIST-F2 is chilled to minus 193°. This minimises background radiation, boosting accuracy.

Ultraprecise timekeeping underlies technologies such as GPS navigation, electric-grid stability, and baking soufflés.

Find out more about how the NIST-F2 atomic clock works in this video…

– Alex Hutchinson

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