Atomic clock
hideAn atomic clock is a type of clock that uses an atomic resonance frequency standard as its timekeeping element. They are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, and to control the frequency of television broadcasts and GPS satellite signals.
Atomic clocks do not use radioactivity, but rather the precise microwave signal that electrons in atoms emit when they change energy levels. Early atomic clocks were masers with attached equipment. Currently the most accurate atomic clocks are based on absorption spectroscopy of cold atoms in atomic fountains such as the NIST-F1.
National standards agencies maintain an accuracy of 10-9 seconds per day (approximately 1 part in 1014), and a precision set by the radio transmitter pumping the maser. The clocks maintain a continuous and stable time scale, International Atomic Time (TAI). For civil time, another time scale is disseminated, Coordinated Universal Time (UTC). UTC is derived from TAI, but synchronized, by using leap seconds, to UT1, which is based on actual rotations of the earth with respect to the mean sun.
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News tagged with atomic clocks
Scientists Build First 'Frequency Comb' To Display Visible 'Teeth'
Oct 29, 2009 |
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(PhysOrg.com) -- Finally, an optical frequency comb that visibly lives up to its name. Scientists at the University of Konstanz in Germany and the National Institute of Standards and Technology in the U.S. ...
Ytterbium's broken symmetry: The largest parity violations ever measured in an atom
Jul 22, 2009 |
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Ytterbium was discovered in 1878, but until it recently became useful in atomic clocks, the soft metal rarely made the news. Now ytterbium has a new claim to scientific fame. Measurements with ytterbium-174, ...
Particle physics study finds new data for extra Z-bosons and potential fifth force of nature
Apr 28, 2009 |
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The Large Hadron Collider is an enormous particle accelerator whose 17-mile tunnel straddles the borders of France and Switzerland. A group of physicists at the University of Nevada, Reno has analyzed data from the accelerator ...
New Research Promises Better Atomic Clocks
Apr 22, 2009 |
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(PhysOrg.com) -- The most accurate timekeepers in the world are atomic clocks, which tell time based on the absorption of a very specific and unchanging microwave frequency, which induces electrons in an atom to “jump” from ...
Atomic fountain clocks are becoming still more stable
Mar 18, 2009 |
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They are at present the most accurate clocks in the world: Caesium fountain clocks furnish the second accurate to 15 places after the decimal point. Until they reach this accuracy, caesium fountain clocks, however, need a ...
