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NASA NTRS1984

Frequency and site selection criteria for MST radars, part 5.1A

The majority of mesosphere-stratosphere-troposphere (MST) and ST radars are located in or near mountainous terrain. When measuring horizontal velocities, the terrain is a small factor, but when measuring vertical velocities, the meteorological noise induced by rough terrain can severely limit the usefulness of the observations. When the variance of the vertical velocity is too large, it is not possible to suitably filter the data to detect the small synoptic-scale signal with reasonable statistical confidence. The variance of vertical velocity at all tropospheric levels is directly related to the low level wind speed during flow over rough terrain. It is suggested that the synoptic-scale vertical velocity can be measured by ST radars where the terrain is smooth. The large-scale vertical velocity cannot always be reliably determined from MST radar data when the underlying terrain is rough. The vertical velocity is potentially on of future radar site selections, taking into account the desired meteorological applications of the data and engineering design factors. If the synoptic-scale vertical velocity is a desired variable, the radar should not be located near mountains.

Nastrom, G. D.↗
NASA NTRS1985

Chemical constraints on the evolution of Archean continental crust

One of the challenges of Archean geochronology is to find isotopic systems that preserve an indication of a rock's primary age in spite of the effects of later metamorphism. Zircon dating has been used widely with considerable success but not without difficulty, especially in polymetamorphic terrains. Zircons in such cases commonly are found to have lost radiogenic Pb, and despite fractionizing the zircons or abrading them to remove disturbed portions; it often is not possible to define a pattern of Pb loss from which the original age can confidently be inferred. The refinement of techniques to enable extremely small samples, or even single crystals, to be analyzed has contributed greatly to solving the problem but even those techniques cannot resolve the micron scale isotopic heterogeneities within single zircons in which much of their history is recorded. That can only be done by ion microprobe. Progress reports on studies of four Archean rocks, each of which illustrates the power and potential of ion microprobe analysis in solving problems of Archean geochronology are discussed.

Weaver, B. L.↗
NASA NTRS1985

Periodic gamma-ray emissions from Geminga at or = 10(12) eV

Analysis of data from an atmospheric Cerenkov telescope indicated the periodic emission of gamma rays of energy 10 to the 12th power eV, at 60.25 second period, from 2CG 195+4. The gamma ray flux at 99% confidence level is estimated to be 9.5 x 10 to 12 photons/sq cm/s.

Kaul, R. K.↗
NASA NTRS1985

Search for gamma ray lines from SS433

Data obtained with the Gamma Ray Spectrometer (0.3 to 9 MeV) aboard the Solar Maximum Mission satellite from 1980 to 1985 for evidence of the reported Doppler shifted lines from SS433 were examined. The data base covers a total of 468 days when SS433 was in the field of view and includes times of quiescent and flaring radio activity. In 9 day integrations of the SMM data no evidence is found for gamma ray line emission from SS433. The 99% confidence upper limits for 9 day integrations of the shifted 1.37 and 6.1 MeV lines are 0.0013 gamma/sq cm-s and 0.0007 gamma/sq cm-s, respectively. The 360 day time averaged upper limits are 0.0002 gamma/sq cm-s x 0.0001 gamma/sq cm-s for both lines.

Geldzahler, B. J.↗
NASA NTRS1985

Observations of potential ultra high energy gamma-ray sources above 10(15) eV

The Haverah Park 50 m water-Cerenkov array has been used to examine a number of periodic sources for ultra high energy gamma-ray emission above 10 to the 15th power eV. The data, recorded between 1 Jan. 1979 and 31 Dec. 1984, feature a modest angular resolution of approx 3 deg with millisecond arrival time resolution post 1982. The sources investigated include the Crab pulsar, Her X-1, Au0115 + 63 and Geminga. All objects have been detected by workers in the TeV region, with varying degrees of confidence.

Lambert, A.↗
NASA NTRS1985

Search for heavy antinuclei in the cosmic radiation

The existence of significant amounts of antimatter in the Universe is demonstrated through cosmic radiation. The data from the Danish-French Cosmic Ray Spectrometer on the HEAO-3 satellite offers an opportunity to search for heavy antinuclei, since all the relevant parameters (charge, velocity, arrival direction, and satellite position at the time of arrival) are measured for each recorded nucleus. Using the 22676 positive only events in the data seletion corresponding to L 1.5 as a measure of our exposure factor to heavy antinuclei and noting that no corresponding antinuclei were found, an upper limit (95% confidence) is given to the ratio of antinuclei to nuclei as 1.4 x .0001 for particles with Z 9. The upper limit resulting from this work is compared with previous results of searches for heavy antimatter in the cosmic radiation. It is seen that, if one regards only antiparticles heavier than fluorine, then the present result represents a reduced upper limit over previous data. When taken together, all the available experiment data now push the upper limit for the ratio of antiparticles to particles well below .0001.

Lund, N.↗
NASA NTRS1979

SRB TPS closeout materials characterization

The recession characteristics of the materials used to closeout the Thermal Protection System (TPS) on the Space Shuttle Solid Rocket Booster (SRB) were assessed. Two candidate closeout materials namely, K5NA and MTA2 is the Marshall Trowelable Ablator. Test panels of each of these two materials were subjected to aerodynamic heat and shear in the NASA Hot Gas Facility. Pretest and Post-test measurements were taken and the rate of recession (R) thus determined was correlated with the heating rate. A least squares curve fit of the data together with another least squares 95% confidence level fit, was performed. The characteristics of the two materials when compared showed that both materials performed equally well at the higher heating rates (10 q 30 Btu/sq ft/sec) but MTA2 was slightly better, not receding as fast, at the lower q values. The comparison of the R versus q curves for K5NA and MTA2 with that of primary TPS P-50 cork on the SRB Aft Skirt was good.

Karu, Z. S.↗
NASA NTRS1985

A cosmic ray super high energy multicore family event. 2: Structure and fragmentation characteristics of the jets

Quarks and gluons are not directly observable, but may be displayed through fragmentation in the form of hadronic jets, the evidence of which was first revealed in cosmic ray interactions before the advent of the modern theory of strong interactions. Experimental results from ISR and SPPS collider rendered the jet phenomena more confident and definite. All the properties of jets observed up to now at ISR and SPPS collider are in agreement with the predictions of QCD. In order to make further test of QCD in still higher energy regions, detailed study of super high energy jet events in cosmic rays is very desirable. The event KO E19 observed in the Mt. Kambala emulsion chamber is an interesting event for such study. The general features of KO E19 is described. Its total visible energy is sigma E sub gamma = 1537 TeV(E sub min = 1.5 TeV) and production height H=(70 + or - 30)m, with a hadron as its primary particle. Besides about forty small clusters, there are five super high energy cores or jets, one lying near the center of the event while the other four surrounding it, having incident directions making small angles with that of the primary particle. Detailed analysis is done on the emulsion plates inserted in the chamber, making full use of their fine granularity, superior in detecting and analyzing jet events, specially their substructures.

Source record↗
NASA NTRS1985

Search for magnetic monopoles using proportional counters filled with helium gas

Slow magnetic monopoles in cosmic rays have been searched at sea level with the detector which consists of seven layers of proportional counters filled with a mixture of He + 20% CH4. The velocities and the energy losses of the incident particles are measured. The upper limit of flux for the monopoles in the velocity range of 1 x 0.001 Beta 4 x 0.001 is 2.78 x 10 to the minus 12th power square centimeters sr sec of 90% confidence level.

Cho, C.↗
NASA NTRS1985

Results from the UCSD magnetic monopole search

The energy loss mechanism for slowly moving magnetic monopoles in helium provides a means of extending the search for such particles by ionization techniques to velocities approximately 3 X 1 million cm/sec (beta approximately equals 0.0001). Other gases (e.g., CH2 or CO2) mixed with helium will be ionized with high efficiency by collisions with excited helium atoms, thus allowing the use of large proportional chamber systems for the detection of the monopoles. The first reported results utilizing this mechanism was the experiment of Kajino, et al., using a detector with an area-solid angle product alpha time delta alpha of 24.7 square meters sr. They set a limit on the flux of monopoles of 7.2 x 10 to the 13th power cm(-2) sr(-1) sec(-1) at a 90% confidence level for beta 3x 0.0001. Here, the results of a He:CH2 proportional tube array designed to extend the velocity limit down to beta approximately 0.0001 are reported. The detector which has been operating at the University of California, San Diego (UCSD) since last summer, is a prototype for a larger array currently under construction at UCSD. The data presented here is from 200 days of live time with the prototype detector.

Masek, G. E.↗
NASA NTRS1985

A search for heavy long lived particles in high energy cosmic rays

The results of an experimental search for energetic particles which arrive at sea level delayed with respect to the shower front, with an order of magnitude greater exposure than previous experiments are presented. The experiment was sensitive to showers from cosmic rays between 10 to the 5th power and 10 to the 7th power Gev per nucleus. No evidence for the existence of heavy long lived particles in air showers was found. An upper limit to the flux of these particles was set at the 90% confidence level of 1.4 x 10 to the minus 12th power cm(-2) sr(-1) s(-1).

Mincer, A.↗
NASA NTRS1984

Results of an irrigated lands assessment for water management in California

Periodic assessment of existing and future demands for water within California is one responsibility of the California Department of Water Resources (CDWR). The California Irrigated Lands Assessment for Water Management Project represented a 5-year joint research effort between the NASA and the CDWR with technical support from the University of California (UC) at Berkeley and at Santa Barbara. The objectives were: (1) to develop and demonstrate procedures for providing highly precise, timely, estimates of irrigated area on a statewide basis using Landsat sensor data, and (2) to develop, through research with small demonstration sites, a procedure for the inventory and mapping of crop groups on a regional basis. Both manual and computer-assisted analyses were investigated. This paper highlights the statewide irrigated lands inventory where a procedure for statewide estimation of irrigated land using full frame Landsat MSS imagery and sampled ground data was successfully demonstrated. The statewide estimate of 3 990 112 hectares was within + or - 1.32 percent relative standard error at the 95-percent Confidence Interval, well within the design goal. This procedure represents a new capability for obtaining near-real time data on changes in agricultural water use throughout the state.

Bauer, E. H.↗
NASA NTRS1984

An analysis of the AVE-SESAME I period using statistical structure and correlation functions

Structure and correlation functions are used to describe atmospheric variability during the 10-11 April day of AVE-SESAME 1979 that coincided with the Red River Valley tornado outbreak. The special mesoscale rawinsonde data are employed in calculations involving temperature, geopotential height, horizontal wind speed and mixing ratio. Functional analyses are performed in both the lower and upper troposphere for the composite 24 h experiment period and at individual 3 h observation times. Results show that mesoscale features are prominent during the composite period. Fields of mixing ratio and horizontal wind speed exhibit the greatest amounts of small-scale variance, whereas temperature and geopotential height contain the least. Results for the nine individual times show that small-scale variance is greatest during the convective outbreak. The functions also are used to estimate random errors in the rawinsonde data. Finally, sensitivity analyses are presented to quantify confidence limits of the structure functions.

Fuelberg, H. E.↗
NASA NTRS1983

The Einstein observatory medium sensitivity survey - The quasars sample

A complete sample of X-ray-selected quasars and Seyfert galaxies extracted from the Einstein Observatory Medium Sensitivity Survey is described, and their physical characteristics are discussed. A Hubble constant of 50 km/s per Mpc and a Friedmann universe with a deceleration parameter of q(0)=0 are assumed throughout the survey, and the sample of X-ray sources was selected according to the following criteria: the significance of the detection exceeds a confidence level of 5 beta; the source is physically unrelated to the target of the IPC observation; and that the source is at a galactic latitude higher than 20 deg. The redshift and optical luminosity distributions of 55 Active Galactic Nuclei (AGNs) detected in the survey are discussed. A number flux relation for the different classes of extragalactic objects are analyzed in detail, using a Maximum Likelihood method and the assumption that the relation can be represented as a power law.

Gioia, I. M.↗
NASA NTRS1983

Gravitational lens effects of a cosmological density of compact objects

Amplification of quasar light by a cosmological density of compact objects causes significant effects on many quasars in magnitude-limited samples. For lens masses solar mass less than 100,000 solar mass the continuum would be amplified by a magnitude or more but the line emission would not. Examination of the UV selected sample of Marshall et al. (1983) gives limits to more than 90 percent statistical confidence of Omega(c) less than 0.1 for a mass between 200 and 100,000 solar mass, where Omega(c) is the mean density of objects of mass M relative to the closure density. Preliminary results from an X-ray selected sample may probe to more than 0.1 solar mass and give a value for Omega(c) of less than one. These limits indicate that the remnants of an early population of massive stars cannot make a cosmologically significant contribution to the mass density of the universe. On a separate topic, recent work on the enhanced surface density of quasars near galaxies due to lensing by stars in the galaxy halos is reviewed.

Canizares, C. R.↗
NASA NTRS1983

QSO X-ray spectra and the contribution of QSOs to the X-ray background radiation

It has been suggested that QSOs make up a substantial fraction of the unresolved X-ray background (XRB) in the 0.5-3 keV energy band. The XRB is poorly known at these energies due to contamination by diffuse galactic emission. The XRB spectrum is precisely measured above 3 keV, and the aggregate spectrum of the proposed contributors should match its form. Seyfert galaxies are thought to contribute 20-30 percent (3-10 keV), and they have been shown to have power-law energy indices of roughly 0.7. The 1-15 keV average spectrum of a sample of optically bright QSOs and a 90 percent confidence range is found for a power law index of 0.83 for N(H) of less than 3 x 10 to the 20th atoms per sq cm. It is also found that QSOs with spectra most consistent with these measurements can contribute about 30 percent at most of the 3-10 keV XRB, or else the remaining contributors have intriguing spectra which rise with energy up to 10 keV and fall sharply thereafter. Alternativey, the X-ray spectral shape of QSOs is a function of redshift and/or radio luminosity.

Worrall, D. M.↗
NASA NTRS1984

Stratospheric circulation in the southern summer/northern winter 1980-81 - Behavior of zonal waves 1-10

Daily global grids of high quality, satellite-borne microwave measurements have been used to study the behavior of stratospheric waves during November 1980-March 1981. The primary motivation was to investigate, by comparing with earlier analyses, the interannual variation of recently reported medium-scale wave domination of Southern Hemisphere (SH) summer circulation. Zonal means, as well as time-mean and transient zonal waves 1-10, are studied. In addition, space-time spectra are determined from the 138-day record. Prominent medium-scale features are found to occur in 1980-81, although wave 4 is strongest, in contrast to the Global Weather Experiment period (1978-79), when wave 5 dominated the SH summer circulation. The same highly continuous, regular eastward phase movement of SH medium-scale waves is found in 1980-81 as in 1978-79. A second noteworthy observation is that of strong, time-mean waves 3-4 with symmetry about the equator, with positive temperature perturbations over the western Pacific and Atlantic equatorial regions, and negative anomalies over South America, Africa, and Indonesia. Confidence in the SH spectral results is enhanced by good agreement between our Northern Hemisphere (NH) medium-scale analyses and recent geopotential height studies by other investigators. These results serve to bring into sharper focus the question of why, in contrast with the more wellknown NH, the SH circulation evidences such robust and highly continuous medium-scale eddies in summer.

Yu, W.-B.↗
NASA NTRS1984

Direct measurement of MPD thrust

An integrally mounted accelerometer has been used to obtain direct thrust measurements during operation of a magnetoplasmadynamic (MPD) thruster. The structural oscillations which can mask the accelerometer output have been ameliorated by stiffening the thruster to increase the lowest resonant frequency above the 1kHz region of interest. In addition, signal conditioning is used to provide a high signal-to-noise accelerometer output waveform. Impulse response measurement of the thruster frequency response function has proven to be an effective means of selecting the signal filter and estimating measurement errors. Comparison of the total impulse derived from the accelerometer output with that from a swinging arm thrust stand indicates 3 percent agreement, providing some confidence in the viability of the accelerometer thrust measurement technique.

Berg, J. M.↗