The gravitational red shift
Relativistic red shift effect and its measurement by hydrogen maser clock
Eby, P.↗
SEARCH · Engineering Papers
Results for “masers”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
An orbiting clock experiment to determine the gravitational red shift
Orbiting clock experiment for measuring gravitational red shift of earth by comparing ground based and satellite-borne hydrogen maser clocks
Kleppner, D.↗
Precise laboratory measurement of the 4830-MHz formaldehyde rotational transition
Formaldehyde rotational transition hyperfine components measured by molecular beam maser
Thaddeus, P.↗
Communications elements research
Investigating superconducting magnets for X band maser and antenna materials for spacecraft
Source record↗
GSFC field operable atomic hydrogen standard research and development
Prototype atomic hydrogen maser standard for field operation
Peters, H. E.↗
Pulsars - Rotating magnetic neutron stars
Pulsars as rotating magnetic neutron stars, examining radio emission via maser amplification
Chiu, H.-Y.↗
Measurement of the gravitational redshift using a clock in an orbiting satellite
A hydrogen maser clock is proposed for enclosure in an orbiting satellite to measure the gravitational effect on time scales with high accuracy. This experiment is used to test the principle of equivalence for clocks in space. Extremely narrow linewidth of Fe-57 radiation and absorption due to Mossbauer effect over 75 ft vertical distance was used to confirm the prediction of the equivalence principle to 1 part in 100. The fractional frequency shift of a satellite-borne oscillator observed from earth is also given.
Vessot, R. F. C.↗
Rubidium gas cell studies
The stability of Rb-87 optically pumped masers and Rb gas cells is examined. Descriptions are given of the technical procedures used in construction and the changes made to solve the problems encountered in the electronics of the systems.
Vanier, J.↗
Spaceborne clock system: Some alternatives for a proposed NASA experiment
A spaceborne clock experiment is proposed with the objectives of improving international time and frequency comparisons, studying precise one-way Doppler tracking and one-way ranging techniques, performing relativistic studies, and developing new atomic frequency standards technology. Various alternatives are considered for accomplishing these goals, including the use of existing satellite and earth-based time dissemination systems as well as the development of a new frequency standard for this specific application. One conclusion is that several attractive alternatives already exist for meeting the goal of improved time and frequency dissemination. However, to achieve all the other 4 goals at the NASA-stated levels of accuracy, a spaceborne atomic frequency standard may be required. An analysis of achievements to date with quartz oscillators, rubidium standards, cesium beam standards, hydrogen masers, and several other possibilities leads to the conclusion that cesium and rubidium standards offer the best choices for the experiment as proposed by NASA. The greatest obstacle to a spaceborne atomic standard appears to be its electrical power requirements.
Beehler, R. E.↗
Hydrogen as an atomic beam standard
After a preliminary discussion of feasibility, new experimental work with a hydrogen beam is described. A space focused magnetic resonance technique with separated oscillatory fields is used with a monochromatic beam of cold hydrogen atoms which are selected from a higher temperature source. The first resonance curves and other experimental results are presented. These results are interpreted from the point of view of accuracy potential and frequency stability, and are compared with hydrogen maser and cesium beam capabilities.
Peters, H. E.↗
Infrared observations of 1612 MHz IR/OH sources.
IR spectra and photometry are given for several IR objects which are known to have 1612 MHz OH emission. These IR/OH sources are shown to be either M type Mira variables or M supergiants with photospheric temperatures around 2000 K. All those examined are oxygen rich and none are carbon stars which suggests a high abundance of OH in their photospheres. A significant fraction of the total luminosity is emitted in the IR beyond 3.5 microns which is taken to imply a dust shell structure around the central star. There is no evidence which uniquely requires that IR pumping of the OH maser is taking place; there are, however, generally enough near infrared photons to supply the observed microwave energy.
Hyland, A. R.↗
Laboratory measurement of the 2-centimeter, 2/11/-2/12/ transition of normal formaldehyde and its carbon-13 and oxygen-18 species.
Beam-maser spectrometric measurements to an accuracy of about 100 Hz have been conducted of the 2(11)-2(12) transition for the isotopic species of greatest astronomical interest - i.e., H2CO, H2(13)CO, and H2C(18)O. The samples used were not isotopically enriched, monomeric formaldehyde vapors. For these species, all the coupling constants required to calculate the hyperfine structure of any rotational transition have been determined.
Tucker, K. D.↗
Interstellar molecules and dense clouds.
Current knowledge of the interstellar medium is discussed on the basis of recent published studies. The subjects considered include optical identification of interstellar molecules, radio molecular lines, interstellar clouds, isotopic abundances, formation and disappearance of interstellar molecules, and interstellar probing techniques. Diagrams are plotted for the distribution of galactic sources exhibiting molecular lines, for hydrogen molecule, hydrogen atom and electron abundances due to ionization, for the densities, velocities and temperature of NH3 in the direction of Sagitarius B2, for the lower rotational energy levels of H2CO, and for temporal spectral variations in masing H2O clouds of the radio source W49. Future applications of the maser and of molecular microscopy in this field are visualized.
Rank, D. M.↗
Precision geodesy via radio interferometry.
Very-long-baseline interferometry experiments, involving observations of extragalactic radio sources, were performed in 1969 to determine the vector separations between antenna sites in Massachusetts and West Virginia. The 845.130-kilometer baseline was estimated from two separate experiments. The results agreed with each other to within 2 meters in all three components and with a special geodetic survey to within 2 meters in length; the differences in baseline direction as determined by the survey and by interferometry corresponded to discrepancies of about 5 meters. The experiments also yielded positions for nine extragalactic radio sources and allowed the hydrogen maser clocks at the two sites to be synchronized.
Hinteregger, H. F.↗
Stellar evolution and pulsars.
It has been found that pulsars are rotating magnetic neutron stars, which are created during catastrophic collapses of old stars whose nuclear fuel has long since been used up. The maximum size of pulsars, based on the fastest rotation period of 33 msec, cannot exceed 100 km. The densest star the theory predicts is the neutron star. Its diameter is only 10 km. The processes producing radiation from pulsars are discussed, giving attention to a process similar to that by which a klystron operates and to a process based on a maser mechanism.
Chiu, H.-Y.↗
Relaxation time measurements by an electronic method.
Description of a simple electronic system that permits the direct measurement of time constants of decaying signals. The system was used in connection with relaxation experiments on hydrogen and rubidium masers and was found to operate well. The use of a computing counter in the systems gives the possibility of making averages on several experiments and obtaining the standard deviation of the results from the mean. The program for the computing counter is given.
Brousseau, R.↗
Hyperfine structure of furan.
The hfs of five rotational transitions of furan (C4H4O) has been resolved with a beam maser spectrometer with a resolution of about 500 Hz. All significant details of the observed structure are accounted for by the spin-spin and spin-rotation interactions of the four protons, and the coupling constants for these interactions have been determined to high precision. In particular, the diagonal elements of the spin-rotation tensors have been determined to about 10 Hz.
Tomasevich, G. R.↗
Low-noise microwave receiving systems in a worldwide network of large antennas.
The Deep-Space Network (DSN) consists of a worldwide network of 26- and 64-m antennas spaced approximately 120 deg around the world. The DSN is a precision communications system designed to communicate with and control unmanned spacecraft traveling at interplanetary ranges. Recent developments in the performance and evaluation of the antennas and maser receivers are discussed, and developments which have contributed to radio-science projects, such as planetary radar astronomy, very-long-baseline interferometry, pulsar, and other astronomical observations are described. It is also shown how these radio-science measurements have been used to evaluate the performance of the antenna-receiver systems.
Reid, M. S.↗