Title
LSRH ammonia masers with twin cavity
Authors
LSRH
Date of Issue
1957-07
Linked Datasets
Same Physical Clock As
99856
Device Type
frequency
Operating Principle
maser
Reference Species
ammonia
Quantum Transition
inversion
J=3, K=3
Reference Frequency
23 870 129 420 Hz
Fabrication Source
noncommercial
Host Institution
LSRH
Status Timeline
Operational: 1957-07 (Bonanomi et al. 1957)
Technical Design aspects: size, design etc.
Ammonia masers (probably the 1956 masers) fitted with a twin-cavity resonator to reduce cavity pulling (Bonanomi et al. 1957)
The resonator consisted of two identical cavities joined together and coupled through an aperture in their common wall; the molecular beam traversed only one of the two cavities. At critical coupling, the maser-frequency versus cavity-tuning characteristic developed a plateau around resonance, strongly reducing the influence of cavity detuning on the oscillation frequency. (Bonanomi et al. 1957)
Technical specifications: stability, precision
Reproducibility / resettability / stability: 2E-10 in 1957; 1E-10 in 1958 (Bonanomi et al. 1957; Bonanomi 1958)
Relative short-term stability: <4E-12 over several minutes, beat frequency between two masers equipped with twin-cavity resonators (Bonanomi 1958)
Modification History
The twin-cavity maser was most probably a modification of the two maser installations constructed in 1956, which are known to have been used with interchangeable resonant cavities.
Usage History
In 1957, the LSRH developed a twin-cavity configuration in which a second cavity was critically coupled to the cavity traversed by the molecular beam, reducing cavity pulling. Two masers equipped with such twin-cavity resonators were subsequently compared experimentally. (Bonanomi et al. 1957; Bonanomi 1958)
In September 1957, the LSRH experimentally compared two 14NH3 masers, one operating on the conventional (J=3, K=3) inversion line and the other on the (J=3, K=2) line at 22 834 185.46 kHz. The experiment, suggested by Charles H. Townes, tested whether the simpler hyperfine structure of the (3,2) transition would reduce the frequency shifts caused by changes in molecular-beam intensity and state-selector voltage. These effects were approximately an order of magnitude smaller on the (3,2) line. Experiments continued in 1958, but the much weaker transition required excessive ammonia flow and was judged unsuitable for reliable atomic-clock operation. (Bonanomi et al. 1957; Bonanomi 1958; LSRH 1958)
Product
bonanomi1957d
bonanomi1957
bonanomi1958
RapportLSRH1958
Identifiers
https://libra.unine.ch/handle/20.500.14713/99858