New atomic fountain clock joins group that keeps the world on time

NIST scientists Greg Hoth (left) and Vladislav Gerginov work on NIST-F4, NIST’s new cesium fountain clock. Credit: R. Eskalis/NIST Clocks on Earth are ticking a bit more regularly thanks to NIST-F4, a new atomic clock at the National Institute of Standards and Technology (NIST) campus in Boulder, Colorado. This month, NIST researchers published a journal article establishing NIST-F4 as one of the world’s most accurate timekeepers. NIST has also submitted the clock for acceptance as a primary frequency standard by the International Bureau of Weights and Measures (BIPM), the body that oversees the world’s time. NIST-F4 measures an unchanging frequency in the heart of cesium atoms, the internationally agreed-upon basis for defining the second since 1967. The clock is based on a “fountain” design that represents the gold standard of accuracy in timekeeping. NIST-F4 ticks at such a steady rate that if it had started running 100 million years ago, when dinosaurs roamed, it would be off by ... Read full article.