CPT maser clock evaluation for Galileo

The CPT maser research project aims to study the feasibility of the clock and to investigate its stability capabilities. A CPT maser prototype is realized and assembled. All the main components which include the optical and electronic systems and physical package are thoroughly tested. Electronics and laser noises are well controlled in the apparatus. Results show that the measured Allan deviation at 1s is quite close to the expected value. No flicker floor is observed in the drift removed data and the medium term stability results to be limited by a thermal drift only. Therefore, a better designed temperature control allows in principle to achieve a medium term stability at the 10^-14 level.