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 N 15 H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> . 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 .