Chu founded a research group at Stanford and continued his particle physics work, overturning a theory on the minimum temperature for multi-level atoms and demonstrating the first atomic fountain
. He and his group also developed a new atom interferometer that exceeded the accuracy of the most accurate commercial inertial sensors.
Using the world's most precise clocks, known as atomic fountain
clocks (SN: 8/7/99, p.
De Voe, rf spectroscopy in an atomic fountain
Chu and graduate student Mark Kasevich conduct the atomic fountain
gravity determination using lasers and magnetic fields to trap about 10 million sodium atoms at a time in a 1-millimeter-diameter zone, thereby cooling them to within 30-millionths of a degree of absolute zero.
29, the National Institute of Standards and Technology (NIST) in Boulder, Colo., switched to a new type of timekeeping technology--the atomic fountain
clock--as the nation's primary time standard (SN: 8/7/99, p.
While other research teams work with fast-moving atomic beams, Chu slowly pumps laser-cooled atoms through his interferometer with an "atomic fountain
" (SN:8/19/89, p.117).
Using pulses of laser light, a team of physicists has succeeded in creating an atomic fountain. The laser pulses push the atoms up; gravity brings them down.
To create an atomic fountain, Chu and his colleagues first use a laser beam to slow a stream of sodium atoms moving toward the laser (see illustration).
Washington, March 19 (ANI): With the aid of a new method developed by scientists in Germany, the output frequency of the atomic fountains
clocks has become more stable.
There is still the idea of motion being measured, but instead of hairsprings and balance wheels, what's being measured is the absorption spectroscopy of cold atoms oscillating in atomic fountains.
As ordinary as they appear, each hangs on your wall, silently listening and reporting back on what's going on in those atomic fountains out West.
Metcalf predicts this method wil not only improve the quality of experiments involving atomic beams, atomic fountains
(SN: 8/19/89, p.117) and laser colling (SN: 8/12/89, p.103) but also will help make possible the development of extremely precise atomic clocks and atomic gyroscopes.