X. Molecular Beams*

Three kinds of research are pursued in the molecular beam laboratory: 1. High-precision studies of atomic and molecular hyperfine structure, an example being the recent discovery and measurement of an octopole interaction in the bromine atom. 2. The development of atomic frequency standards by using atomic and molecularbeam techniques. The carbon monoxide electric resonance studies and the ammonia molecule decelerator are examples. Work is also being done to determine the basic characteristics of an atomic frequency standard that makes use of a cesium beam tube as a frequency reference, and to develop complementary electronics to realize its latent frequency stability. Studies are also being made of a method of generating an extremely stable microwave signal by using a super-cooled lead cavity oscillator. This could replace the usual crystal oscillator-harmonic generator method of beam-tube excitation. 3. Experiments that apply parts of these techniques to interesting problems in any area of physics, for instance, the measurement of the velocity of light in terms of atomic standards or the search for a charge carried by molecules.