NIST-F2 is a caesium fountain atomic clock

Atomic clock

An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...

 under construction that will serve as the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

' primary time

Time

Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....

 and frequency standard. The clock will replace NIST-F1

NIST-F1

NIST-F1 is a cesium fountain clock or atomic clock in the National Institute of Standards and Technology in Boulder, Colorado, and serves as the United States' primary time and frequency standard...

, a caesium fountain atomic clock used since 1999. NIST-F1 has a fractional inaccuracy of less than δf/f < 5  × 10⁻¹⁶, the planned performance of NIST-F2 is δf/f < 1 × 10⁻¹⁶.

External links and references

• NIST Time and Frequency Div. — 2004: Strategic Focus 1 (National Institute of Standards and Technology)
• Wired.com How Super-Precise Atomic Clocks Will Change the World in a Decade