Investigations of masers utilizing cross-relaxation
Cross relaxation processes in millimeter wave maser technology for obtaining maser amplification at higher frequencies
MILLIMETER WAVE↗
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Hydrogen-maser principles and techniques.
Hydrogen maser construction and operation design principles emphasizing microwave cavity, low magnetic field, hydrogen storage and maser tuning techniques
HYDROGEN↗
Proposed gas maser pumping scheme for the far infrared.
Gas maser pump analogous to operation of heat engine for exciting maser action in far IR, DETAILING interaction between pure rotational states of HCl and HF
FAR INFRARED↗
The nonlinear theory of slow-wave electron cyclotron masers with inclusion of the beam velocity spread
The nonlinear theory of slow-wave electron cyclotron masers (ECM) with an initially straight electron beam is developed. The evolution equation of the nonlinear beam electron energy is derived. The numerical studies of the slow-wave ECM efficiency with inclusion of Gaussian beam velocity spread are presented. It is shown that the velocity spread reduces the interaction efficiency. -- Highlights: •The theory of slow-wave electron cyclotron masers is considered. •The calculation of efficiency under the resonance condition is presented. •The efficiency under Gaussian velocity spreads has been obtained.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
CEPHEID VARIABLES IN THE MASER-HOST GALAXY NGC 4258
We present results of a ground-based survey for Cepheid variables in NGC 4258. This galaxy plays a key role in the Extragalactic Distance Scale due to its very precise and accurate distance determination via very long baseline interferometry observations of water masers. We imaged two fields within this galaxy using the Gemini North telescope and the Gemini Multi-Object Spectrograph, obtaining 16 epochs of data in the Sloan Digital Sky Survey gri bands over 4 yr. We carried out point-spread function photometry and detected 94 Cepheids with periods between 7 and 127 days, as well as an additional 215 variables which may be Cepheids or Population II pulsators. We used the Cepheid sample to test the absolute calibration of theoretical gri Period–Luminosity relations and found good agreement with the maser distance to this galaxy. The expected data products from the Large Synoptic Survey Telescope should enable Cepheid searches out to at least 10 Mpc.
79 ASTRONOMY AND ASTROPHYSICS↗
Parametric up-converter increases flexibility of maser
Parametric up-converter translates a broad band of signals to the fixed tuned input frequency of a maser. This modified maser can operate in the 1700-2300 Mc range, eliminating the need to duplicate equipment. It may be applied in communications and radio astronomy.
Summy, R. H.↗
Thermal short improves sensitivity of cryogenically cooled maser
In-line, quarter-wave thermal short cools the center conductor of the signal-input coaxial transmission line to a cryogenically cooled traveling wave maser. It reduces both the thermal noise contribution of the coaxial line and the heat leak through the center conductor to the maser at 4.4 degrees K.
Clauss, R. C.↗
Hydrogen maser for field use Technical report, Jun. 27, 1966 - Jan. 30, 1968
Hydrogen maser for field use with cavity and bulb design of maser for satellite applications
Mueller, L.↗
Atomic Hydrogen Maser for Space Vehicle Application, Phase 2 Final Report
Thermal design of hydrogen maser and wall coatings for maser bulb
Vessot, R. F. C.↗
Contribution of the spatial part of the metric tensor to the observed frequency shift in the maser clock experiment
Formula for frequency shift of maser clock in orbit to identical maser on earth
Eby, P.↗
Measurement of the power spectral density of phase of the hydrogen maser
Hydrogen masers are being developed for the Deep Space Network as improved frequency standards, in order to achieve better timing accuracies, reduced Doppler residuals, and lower phase noise in the tracking system. Performance data for the masers are given in two forms: time domain performance, useful for analyzing time keeping systems and Doppler systems; and frequency domain performance, useful for analyzing tracking systems. Particular attention is given to frequency domain performance, as obtained from both time domain measurements and direct measurements.
Sward, A.↗
Research on Haystack radiometer, 20-24 GHz maser, and radio astronomy programs
During the first half of 1973, the Haystack antenna was utilized 76% of the time. Of this useful time, 72% was devoted to radio astronomy observing, 5% was spent on radar-related research and 23% went into maintenance and system improvements. Twenty-eight new radio astronomy programs were accepted, eight of which were completed during the period. One new radar program, topographic observations of Mars, was started in June and will be completed early in 1974. Fourteen programs continued from the previous period were also defined as complete. As of 1 July, 28 ratio observing programs were in a continuing status on the Haystack books. Four radar projects were also continuing. The 20-24 GHz maser development described in the preceding report progressed very well during an on-antenna test phase which began early in the year, but which terminated unfortunately in June with the complete loss of gain in the maser. Investigation of this problem is in progress. During this on-antenna test phase, the most sensitive water vapor observing capability which has yet become available was demonstrated.
Source record↗
Light shift effects in the Rb-87 maser
Previous work has shown the possibility to overcome the dependence of the Rb-87 maser frequency on light intensity by tuning the cavity at a proper setting. The conditions for this setting, called the light-independent frequency setting (LIFS), are carefully investigated. The results presented prove the existence of the LIFS and provide a new criterion for an automatic cavity tuning of the Rb maser.
Busca, G.↗
Cavity tuning and light-shift in the Rb-87 maser
A new method for tuning the cavity of the Rb-87 maser is proposed. It is based on the existence of a cavity tuning for which the maser frequency is independent on the light intensity. The features of this method are evaluated theoretically and tested experimentally. Preliminary results obtained by using a closed loop feedback electronic system for tuning the cavity are given.
Busca, G.↗
Infrared pumping processes for SiO masers
The J = 2 to 1 transition of the first excited vibrational state (v = 1) Si(28)O(16) has recently been shown to produce maser amplification near 86,245 MHz in Orion A and in several stars. Two possible pumping mechanisms are proposed for such masers. One involves the near coincidence between the frequencies of the 1-0 (RO) and 3-2 (R18) transitions in Si(28)O(16). The other requires emission by SiO and reabsorption without the necessity for an accidental frequency coincidence. Each of these types of mechanisms may occur for other transitions of molecules in a medium illuminated by intense infrared radiation, or with strong temperature gradients.
Geballe, T. R.↗
Reflected-wave maser
Reflected wave maser amplifier has significantly greater bandwidth than conventional maser amplifiers. Unit needs no retuning to receive wide range of frequencies.
Clauss, R. C.↗
Design and analysis of optically pumped submillimeter waveguide maser amplifiers and oscillators
The design and experimental measurements are described of an optically pumped far-infrared (FIR) waveguide maser; preliminary measurements on a FIR waveguide amplifier are presented. The FIR maser was found to operate satisfactorily in a chopped CW mode using either methanol (CH3OH) or acetonitrile (CH3CN) as the active molecule. Two other gases, difluoroethane and difluoroethylene, produced an unstable output with high threshold and low output power when operated in the chopped CW mode. Experimental measurements include FIR output versus cavity length, output beam pattern, output power versus pressure, and input power. The FIR output was the input to an amplifier which was constructed similar to the oscillator. An increase of 10% in output power was noted on the 118.8 microns line of methanol.
Galantowicz, T. A.↗
An improved method for measuring the magnetic inhomogeneity shift in hydrogen masers
The reported method makes it possible to conduct all maser frequency measurements under conditions of low magnetic field intensity for which the hydrogen maser is most stable. Aspects concerning the origin of the magnetic inhomogeneity shift are examined and the available approaches for measuring this shift are considered, taking into account certain drawbacks of currently used methods. An approach free of these drawbacks can be based on the measurement of changes in a parameter representing the difference between the number of atoms in the involved states.
Reinhardt, V. S.↗