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
3
. 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
.