In order to evaluate an atomic clock, it is important to determine the main frequency shifts caused by external fields, device imperfections, etc. Scanning the frequency of the main oscillator, the Ramsey fringe is obtained and used to determine the main shifts. The gravitational shift (10-17), second order Doppler (1.65×10-13), Black-Body radiation shift (2.9×10-14), quadratic Zeeman effect (5×10-13), Rabi Pulling (1.3×10-13) and cavity pulling (1.3×10-13) have been evaluated. The short term stability, (6.6±0,2)×10-13, was obtained.
