![]() The other atoms are absorbed by another carbon getter. The B magnet deflects the in-step atoms towards a detector, the hot wire cesium ionizer and ion collector. The B magnet collects the cesium atoms that stayed in step with the microwaves, and which now have their magnetization pointing the other way (the cesium-133 atoms in the f=4 level). The spinning is stopped by the microwaves at the other end of the Ramsey cavity. (Quantum mechanics describe these cesium-133 atoms as an oscillating combination of the two hyperfine levels, f=4 and f=3.) Magnetic shielding isolates the atoms from outside magnetic fields. Allowing for tiny corrections, their magnetization spins at 9 192 631 770 rotations per second in a very uniform magnetic field, the C field of less than 1/10 the Earth's magnetic field. Some atoms have their magnets set spinning by microwaves in the Ramsey cavity. The A magnet selects cesium atoms with their atomic magnets pointing one way (those in the f=3 level of the ground state of the cesium-133 atom), and sends other atoms to be absorbed by a carbon getter. How does it all work?Ĭesium is evaporated at the cesium source to form a beam of well-separated cesium atoms that travel without collisions at about 250 m/s, through a vacuum maintained by the vacuum pump. The clock is located in a copper room to isolate it from radio interference. Cesium atoms are emitted at one end of the tube and pass through two microwave cavities (the copper waveguide which feeds the microwaves to these cavities can be seen above the tube) before they are analyzed and detected at the other end. The large aluminium tube is a vacuum vessel which contains the heart of the clock. Officers in the Frequency and Time group, make adjustments to one of the NRC-built cesium atomic clocks. ![]() Jean-Simon Boulanger and Rob Douglas, Research ![]()
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