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Atomic clocks are installed at sites of time signal radio transmitters. [113] They are used at some long-wave and medium-wave broadcasting stations to deliver a very precise carrier frequency. [114] Atomic clocks are used in many scientific disciplines, such as for long-baseline interferometry in radio astronomy. [115]
A caesium atomic fountain used as part of an atomic clock. 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.
Caesium is widely used in highly accurate atomic clocks. In 1967, the International System of Units began using a specific hyperfine transition of neutral caesium-133 atoms to define the basic unit of time, the second.
The resonant element in atomic clocks utilizes the hyperfine structure of rubidium's energy levels, and rubidium is useful for high-precision timing. It is used as the main component of secondary frequency references (rubidium oscillators) in cell site transmitters and other electronic transmitting, networking, and test equipment.
This is a list of some experimental laboratory atomic clocks worldwide. This list is incomplete; you can help by adding missing items. (March 2013) Name
The clock took fewer than four years to test and build, and was developed by Steve Jefferts and Dawn Meekhof of the Time and Frequency Division of NIST's Physical Measurement Laboratory. [1] The clock replaced NIST-7, a cesium beam atomic clock used from 1993 to 1999. NIST-F1 is ten times more accurate than NIST-7.
NIST-F1, a cesium fountain atomic clock used since 1999, has a fractional inaccuracy (δf / f) of less than 5 × 10 −16. The planned performance of NIST-F2 is δ f / f < 1 × 10 −16 . [ 3 ] At this planned performance level the NIST-F2 clock will not gain or lose a second in at least 300 million years.
The Deep Space Atomic Clock (DSAC) under development by the Jet Propulsion Laboratory utilises mercury in a linear ion-trap-based clock. The novel use of mercury permits the creation of compact atomic clocks with low energy requirements ideal for space probes and Mars missions.