U.S. Department of Commerce's National Institute of Standards and Technology (NIST) has launched a new atomic clock, called NIST-F2, which will serve as the new US time standard, and will neither gain nor lose one second in about 300 million years.
The new quality makes the atomic clock makes it about three times as accurate as NIST-F1, which has served as the standard since 1999. Both clocks use a "fountain" of cesium atoms to determine the exact length of a second.
NIST scientists recently reported the first official performance data for NIST-F2, which has been under development for a decade, to the International Bureau of Weights and Measures (BIPM), located near Paris, France. That agency collates data from atomic clocks around the world to produce Coordinated Universal Time (UTC), the international standard of time. According to BIPM data, NIST-F2 is now the world's most accurate time standard.
Both NIST-F1 and NIST-F2 measure the frequency of a particular transition in the cesium atom-which is 9,192,631,770 vibrations per second, and is used to define the second, the international (SI) unit of time. The key operational difference is that F1 operates near room temperature (about 27 degreeC or 80 degreeF) whereas the atoms in F2 are shielded within a much colder environment (at minus 193 degreeC, or minus 316 degreeF).
This cooling dramatically lowers the background radiation and thus reduces some of the very small measurement errors that must be corrected in NIST-F1.
