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NIST-F1 is a cesium fountain clock, a type of atomic clock, in the National Institute of Standards and Technology (NIST) in Boulder, Colorado, and serves as the United States' primary time and frequency standard. The clock took fewer than four years to test and build, and was developed by Steve Jefferts and Dawn Meekhof of the Time and ...
NIST physicists Steve Jefferts (foreground) and Tom Heavner with the NIST-F2 cesium fountain atomic clock, a civilian time standard for the United States. NIST-F2 is a caesium fountain atomic clock that, along with NIST-F1, serves as the United States' primary time and frequency standard. [1] NIST-F2 was brought online on 3 April 2014. [1] [2]
Download QR code; Print/export ... optical standards has been treated in a major review (Ludlow ... like the United States Time Standard atomic clocks, NIST-F1 and ...
Download QR code; Print/export Download as PDF; ... 18 cesium atomic clocks and 4 hydrogen maser clocks ... National Standard Time and Frequency Laboratory;
International Atomic Time (abbreviated TAI, from its French name temps atomique international [1]) is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid. [2] TAI is a weighted average of the time kept by over 450 atomic clocks in over 80 national laboratories worldwide. [3]
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 primary time standard in the U.S. is currently NIST-F1, a laser-cooled Cs fountain, [34] the latest in a series of time and frequency standards, from the ammonia-based atomic clock (1949) to the caesium-based NBS-1 (1952) to NIST-7 (1993).