FREQUENCY PULLING BY HYPERFINE SIGMA-TRANSITIONS IN CESIUM BEAM ATOMIC FREQUENCY STANDARDS

It is demonstrated that frequency pulling by DELTA-m = +/- 1 hyperfine sigma transitions, here called Ramsey pulling, is a real calculable effect in atomic beam frequency standards. An analytic expression for the effects of Ramsey pulling is derived using perturbative techniques for the driving sigma transitions, while treating the primary pi transitions exactly. It is shown that these Ramsey pulling effects are intrinsically different from Rabi pulling in origin, manifestation, and elimination. These predictions are compared to measurements performed on a cesium beam atomic frequency standard, giving good quantitative verification of the theory and a clear demonstration of the existence of these effects.