31,602 research outputs found
A method of eliminating hydrogen maser wall shift
Maser output frequency shift was prevented by storage bulb kept at temperature at which wall shift is zero and effects of bulb size, shape, and surface texture are eliminated. Servo system is shown, along with bidirectional counter
System automatically tunes hydrogen masers
Automatic tuning system permits frequency synchronization between two hydrogen masers. System matches spaceborne clock performance with that of ground-based clock to test red shift theory. This system, used in conjunction with radio astronomy for long-baseline interferometer experiments, serves as a tool for investigation of distant universe phenomena
Condensation and coexistence in a two-species driven model
Condensation transition in two-species driven systems in a ring geometry is
studied in the case where current-density relation of a domain of particles
exhibits two degenerate maxima. It is found that the two maximal current phases
coexist both in the fluctuating domains of the fluid and in the condensate,
when it exists. This has a profound effect on the steady state properties of
the model. In particular, phase separation becomes more favorable, as compared
with the case of a single maximum in the current-density relation. Moreover, a
selection mechanism imposes equal currents flowing out of the condensate,
resulting in a neutral fluid even when the total number of particles of the two
species are not equal. In this case the particle imbalance shows up only in the
condensate
Aperture synthesis for microwave radiometers in space
A technique is described for obtaining passive microwave measurements from space with high spatial resolution for remote sensing applications. The technique involves measuring the product of the signal from pairs of antennas at many different antenna spacings, thereby mapping the correlation function of antenna voltage. The intensity of radiation at the source can be obtained from the Fourier transform of this correlation function. Theory is presented to show how the technique can be applied to large extended sources such as the Earth when observed from space. Details are presented for a system with uniformly spaced measurements
Hydrogen-maser time and frequency standard at Agassiz Observatory
Installation of hydrogen maser for very long baseline interferometr
Gravitational redshift space-probe experiment
A Scout D rocket was launched from Wallops Island, Virginia, carrying an atomic hydrogen maser oscillator system as the payload. The frequency of signals from the oscillator was monitored on the ground at Merritt Island, Florida, by using two hydrogen masers as comparison oscillators. The first-order Doppler shift in the signals was eliminated by a go-return transponder link to the payload, and the resulting data, representing the relativistic shifts, were recovered and recorded. The objective was to measure directly the effect of gravitational potential on the frequency of an atomic hydrogen maser assuming it to be a 'proper' clock. A gravitational effect amounting to some 4.5 parts in 10 to the 10th power was measured with an oscillator having a stability better than 1 part in 10 to the 14th power. Therefore, to make the best possible use of the oscillator, all frequency shifts at the 2 to 5 X 10 to the -15 power level in delta f/f in the system must be accounted for. This includes all the phase variations that can cause such a shift to appear. The experiment, the data available and the manner in which they were processed, and the results are described
Use of quantitative micro-complement fixation for detection of small differences in protein structure
Quantitative micro-complement fixation for detection of small differences in protein structur
Tunable cavity resonator with ramp shaped supports
A cavity for a hydrogen maser is described consisting of three parts which provide highly stable mechanical and thermal expansion characteristics for the cavity and ease of tuning. The three parts which are made of a glass ceramic material having a very small thermal expansion coefficient (1) a top plate, (2) a cylinder with three interrupted helical ramps at its bottom, and (3) a base which includes a bottom plate and three ramp lugs on which the helical ramps of the cylinder rest when the cylinder is placed on the base with the bottom plate in the cylinder. Cavity tuning is achieved by rotating the cylinder and thereby raising or lowering it on the base, which results in changing the cylinder volume by changing the distance between the bottom and top plates
The effect of electromagnetic properties of neutrinos on the photon-neutrino decoupling temperature
We examine the impact of electromagnetic properties of neutrinos on the
annihilation of relic neutrinos with ultra high energy cosmic neutrinos for the
process. For this process, photon-neutrino
decoupling temperature is calculated via effective lagrangian model beyond the
standard model. We find that photon-neutrino decoupling temperature can be
importantly reduced below the QCD phase transition with the model independent
analysis defining electromagnetic properties of neutrinos.Comment: 12 pages, 3 figures, published versio
Topographic Signatures in Aquarius Radiometer/Scatterometer Response: Initial Results
The effect of topography on remote sensing at L-band is examined using the co-located Aquarius radiometer and scatterometer observations over land. A correlation with slope standard deviation is demonstrated for both the radiometer and scatterometer at topographic scales. Although the goal of Aquarius is remote sensing of sea surface salinity, the radiometer and scatterometer are on continuously and collect data for remote sensing research over land. Research is reported here using the data over land to determine if topography could have impact on the passive remote sensing at L-band. In this study, we report observations from two study regions: North Africa between 15 deg and 30 deg Northern latitudes and Australia less the Tasmania Island. Common to these two regions are the semi-arid climate and low population density; both favorable conditions to isolate the effect of topography from other sources of scatter and emission such as vegetation and urban areas. Over these study regions, topographic scale slopes within each Aquarius pixel are computed and their standard deviations are compared with Aquarius scatterometer and radiometer observations over a 36 day period between days 275 and 311 of 2011
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