One variety of this object uses magnetic fields to separate particles according to their spin energies—the beam variety, which is contrasted with the fountain kind.
One variety of this object uses magnetic fields to separate particles according to their spin energies—the beam variety, which is contrasted with the fountain kind. These objects, conceived by Isidor Rabi, were used to test the theory of special relativity in the Hafele-Keating experiment, in which they were flown around the world in airplanes in opposite directions to measure time dilation. The principal one for the US is located in Boulder at NIST, and provides synchronization capabilities integral to the operation of GPS. Often based on alkali metals like rubidium or cesium, name these objects that measure the frequency of quantum energy level transitions to keep time.
One variety of this object uses magnetic fields to separate particles according to their spin energies—the beam variety, which is contrasted with the fountain kind.
{atomic clocks} [accept {modifiers} of “{beam}” or “{fountain}” before {both} have {been} mentioned]