EVALUATION OF THE 2ND-ORDER DOPPLER-SHIFT IN THE MG FREQUENCY STANDARD

We report in this paper the first evaluation of the second-order Doppl er shift in the Mg frequency standard. Three methods are considered: d irect theoretical computation, Fourier analysis of the experimental Ra msey curve, and Fourier analysis of the discrimination curve. The resu lts obtained are compared in a practical experimental case and turn ou t in satisfactory agreement, allowing a good confidence on the determi nation of the shift at the accuracy level of +/-3 x 10(-13). The consi derations reported in this paper may be of general interest for freque ncy standards based on atomic or molecular beams with transverse dimen sions much larger than the transition wavelength.