N15H3 Double-Beam Maser as a Primary Frequency Standard

Ammonia masers are studied concerning their use as frequency standards. They oscillate on the J = K = 3 inversion line of N¹⁵H3. Single beam masers allow the realization of a frequency standard with a stability of 2-3.10^-11, and an accuracy of about 10^-9. Experiments on double beam masers suggest that their use makes it possible to obtain a stability of the order of 10^-12 and an accuracy better than 10^-10.