New clock is three times more accurate than previous atomic clocks
Uses ‘fountain’ of cesium atoms to determine the exact length of a second
will be used by mobile phones, banking systems and GPS
The U.S. Department of Commerce’s National Institute of Standards and Technology (NIST) says the new atomic clock, called NIST-F2, will now be the U.S. civilian time and frequency standard.
It is three times more accurate than previous atomic clocks, and uses a ‘fountain’ of cesium atoms to determine the exact length of a second.
NIST-F2 would neither gain nor lose one second in about 300 million years, making 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.
HOW THE ATOMIC CLOCK WORKS
NIST-F1 and NIST-F2 are called fountain clocks because the cesium atoms are tossed in the air and fall back down inside a vertical tube during a key routine repeated thousands of times an hour.
A gas of cesium atoms is introduced into the clock’s vacuum chamber and six infrared laser beams gently push about 10 million atoms into a ball. In this process, the lasers cool the atoms to temperatures near absolute zero and slow them down significantly, to enable precise measurements of their natural vibrations.
Two vertical laser beams produced by the six lasers are used to gently toss the atom balls upward through the flight chamber (the “fountain” action), and then all of the lasers are turned off.
This little push is just enough to loft the ball about 1.3 meters high through a microwave-filled cavity. Gravity brings the ball back down through the microwave cavity.