Atomic Beam Frequency Standards

Publisher Summary This chapter examines the various aspects of the atomic beam frequency standards. A description of the spectrum upon which the cesium standard is based is presented. The quantum transitions employed in present day atomic beam standards occur between the hyperfine levels in the ground state of the alkali metal cesium. The hyperfine splitting arises because of the interaction between the magnetic moment of the nucleus and the magnetic field produced by the valence electron at the position of the nucleus. The vector model is a simple and useful concept for the analysis of the fine and hyperfine structure of atoms in either very weak or very strong externally applied fields. The atomic trajectories and deflections can be calculated rather simply for the elementary field configurations ordinarily used in the deflecting fields of atomic beam machines. The beam intensity and intensity distribution are elaborated. The transition probability for two separated oscillating fields is also described.