PROPERTIES OF AN OPTICALLY PUMPED CESIUM-BEAM FREQUENCY STANDARD WITHPHI=PI BETWEEN THE 2 OSCILLATORY FIELDS

The properties of optically pumped cesium-beam resonators showing a ph ase difference, PHI, of pi between the two oscillatory fields are anal yzed. They are compared with those occurring with PHI = 0, when the in terrogation signal is slowly square-wave frequency modulated. The valu e of the operating parameters which optimizes the resonator properties is given for PHI = 0 and pi, taking into account the effect of the no ise sources which perturb the atom detection. It is shown that the des ign with PHI = pi is superior. It provides a better frequency stabilit y and smaller frequency offsets. The conclusion holds for short as wel l as long tubes.