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Atomic clocks are installed at sites of time signal radio transmitters. [103] They are used at some long-wave and medium-wave broadcasting stations to deliver a very precise carrier frequency. [104] Atomic clocks are used in many scientific disciplines, such as for long-baseline interferometry in radio astronomy. [105]
TAI is a weighted average of the time kept by over 450 atomic clocks in over 80 national laboratories worldwide. [3] 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 ...
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 Atomichron was the world's first commercial atomic clock, built by the National Company, Inc. of Malden, Massachusetts. It was also the first self-contained portable atomic clock and was a caesium standard clock. More than 50 clocks with the trademarked Atomichron name were produced. [1] [2] [3] [4]
The meaning of the preceding definition is as follows. The caesium atom has a ground state electron state with configuration [Xe] 6s 1 and, consequently, atomic term symbol 2 S 1/2. This means that there is one unpaired electron and the total electron spin of the atom is 1/2. Moreover, the nucleus of caesium-133 has a nuclear spin equal to 7/2.
The Bulletin of the Atomic Scientists set the clock to 89 seconds before midnight - the theoretical point of annihilation. That is one second closer than it was set last year.
Leonard Rieser, chairman of the board of the Bulletin of the Atomic Scientists, moves the hand of the Doomsday Clock back to 17 minutes before midnight on Nov. 26, 1991.
The caesium atomic clock maintained by NIST is accurate to 30 billionths of a second per year. [206] Atomic clocks have employed other elements, such as hydrogen and rubidium vapor, offering greater stability (in the case of hydrogen clocks) and smaller size, lower power consumption, and thus lower cost (in the case of rubidium clocks). [206]