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Results for “synchrotron x-ray imaging”

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.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Dynamical diffraction imaging (topography) with X-ray synchrotron radiation

By contrast to electron microscopy, which yields information on the location of features in small regions of materials, X-ray diffraction imaging can portray minute deviations from perfect crystalline order over larger areas. Synchrotron radiation-based X-ray optics technology uses a highly parallel incident beam to eliminate ambiguities in the interpretation of image details; scattering phenomena previously unobserved are now readily detected. Synchrotron diffraction imaging renders high-resolution, real-time, in situ observations of materials under pertinent environmental conditions possible.

Kuriyama, M.↗
NASA NTRS1988

X-ray diffraction imaging (topography) of electroopticcrystals by synchrotron radiation

Information of special interest to crystal growers and device physicists now available from monochromatic synchrotron diffraction imaging (topography) is reviewed. Illustrations are taken from a variety of electro-optic crystals. Aspects of the detailed understanding of crystal growth processes obtainable from carefully selected samples are described. Finally, new experimental opportunities now available for exploitation are indicated.

Steiner, Bruce↗
NASA NTRS1986

Grazing incidence optics; Proceedings of the Meeting, Orlando, FL, Apr. 3, 4, 1986

Papers are presented on the diffraction-limited performance of grazing incidence optical systems; transverse ray aberrations of Wolter type 1 telescopes; hybrid X-ray telescope systems; surface characterization of grazing incidence optics in the extreme UV and X-ray regions; and the surface roughness properties of synchrotron radiation optics. Topics discussed include the simulation of free-abrasive grinding of grazing incidence mirrors with vertical-honing and flexible blades; mirrors for the Extreme Ultraviolet Explorer; the design and development of conical X-ray imaging mirrors; thermal loading considerations for synchrotron radiation mirrors; and grazing incidence optics for synchrotron radiation insertion-device beams. Consideration is given to the interpretation of glancing incidence scattering measurements; damage processes in short wavelength coated FEL optics; the replication of grain incidence optics; and the assembly and alignment of the Technology Mirror Assembly.

Osantowski, John F.↗
NASA NTRS1988

Applications of synchrotron radiation to materials science: Diffraction imaging (topography) and microradiography

Synchrotron radiation sources are now available throughout the world. The use of hard X-ray radiation from these sources for materials science is described with emphasis on diffraction imaging for material characterization. With the availability of synchrotron radiation, real-time in situ measurements of dynamic microstructural phenomena have been started. This is a new area where traditional application of X-rays has been superseded. Examples are chosen from limited areas and are by no means exhaustive. The new emerging information will, no doubt, have great impact on materials science and engineering.

Kuriyama, Masao↗
NASA NTRS1990

The metrology of spherical shells using synchrotron x ray microtomography

With recent advances in solid state imaging technology and the increasing availability of synchrotron x-ray radiation sources, synchrotron x-ray microtomography is emerging as a nondestructive technique for the evaluation of the structure and composition of small specimens with spatial resolution in the micron range. Synchrotron radiation offers the following advantages over conventional x-ray sources: high brightness, continuous emission which is tunable over a large energy range, faster data collection rates, and a highly collimated beam of large cross section permitting the illumination of large specimens. Synchrotron x-ray microtomography enables the structure of individual spheres to be evaluated in order to reveal the concentricity and sphericity of the internal void and the uniformity of the shell wall in the case of high quality spherical shells for Sandia National Laboratories' Inertial Confinement Fusion project.

Hmelo, Anthony B.↗
NASA NTRS1989

Center for the development of commercial crystal growth in space

The second year of operation of the Center for Commercial Crystal Growth in Space is described. This center is a consortium of businesses, universities and national laboratories. The primary goal of the Center's research is the development of commercial crystal growth in space. A secondary goal is to develop scientific understanding and technology which will improve commercial crystal growth on earth. In order to achieve these goals the Center's research is organized into teams by growth technique; melt growth, solution growth, and vapor growth. The melt growth team is working on solidification and characterization of bulk crystals of gallium arsenide and cadmium telluride. They used high resolution X-ray topography performed at the National Synchrotron Light Source at Brookhaven National Laboratory. Streak-like features were found in the diffraction images of semi-insulating undoped LEC GaAs. These were shown to be (110) antiphase boundaries, which have not been reported before but appear to be pervasive and responsible for features seen via less-sensitive characterization methods. The results on CdTe were not as definitive, but indicate that antiphase boundaries may also be responsible for the double peaks often seen in X-ray rocking curves of this material. A liquid encapsulated melt zone system for GaAs has been assembled and techniques for casting feed rods developed. It was found that scratching the inside of the quartz ampoules with silicon carbide abrasive minimized sticking of the GaAs to the quartz. Twelve floating zone experiments were done.

Wilcox, William R.↗
NASA NTRS1985

X-ray images of W28 and 3C400.2 - Two radio-shell supernova remnants with centrally-peaked X-ray emission

X-ray images of the supernova remnants (SNRs) W28 and 3C400.2 were obtained using the Imaging Proportional Counter (IPC) on the Einstein Observatory. Despite the shell-like radio morphology of these remnants, their X-ray emission is centrally peaked. Two possible X-ray emission mechanisms are explored: synchrotron emission due to an active central pulsar, and thermal emission from a thin hot plasma filling the interior of the remnant. Comparisons of X-ray and radio properties of W28 and 3C400.2 with known Crab-like remnants suggest that synchrotron emission is not a very plausible X-ray emission mechanism. Optical and radio observations suggest that both SNRs exploded in a dense cloud and have evolved rapidly to the radiative stage. The X-ray morphology observed is similar to that predicted for SNRs in such an environment.

Matsui, Y.↗
NASA NTRS1988

An X-ray and radio study of steep-spectrum radio soruces. I - Four fields from the Clark Lake Observatory 26 MHz survey

A multifrequency study of fields containing steep-spectrum radio sources is presented. New spectral and spatial data are used to determine the locations and optical identifications of steep-spectrum sources which previously had either poor positions or questionable correspondence to known sources. X-ray images from the Einstein Observatory provide estimates of the extent, temperature, density, and thermal pressure of hot gas associated with galaxies and clusters of galaxies. From the equations relating synchrotron emission to inverse Compton scattering of 3 K background photons, lower limits to the average magnetic field strength in the source are derived. For the resolved radio sources of known distance, the minimum nonthermal pressure and the corresponding magnetic field strength are also calculated. For the four fields discussed in this paper, it is found that three out of five steep-spectrum sources are embedded in a cluster atmosphere and two are unidentified. Except for unresolved radio structures associated with cores of galaxies, the estimated thermal pressure is sufficient to confine the radio sources.

Harris, D. E.↗
NASA NTRS1983

Radio and X-ray observations of the radio halo source in A1367

Radio and X-ray observations of the 'radio halo' in A1367 are presented. The radio spectral index distribution is derived combining data at 610 and 1415 MHz taken with the Westerbork Synthesis Radio Telescope (WSRT). A high-resolution Very Large Array (VLA) map allows us to discriminate between the extended cluster emission and a triple radio source associated with a background stellar object (most probably a QSO) which appears projected onto it. X-ray observations taken with the high-resolution imager on board the Einstein satellite reveal an X-ray source associated with this background object. A second weak X-ray enhancement is found projected onto the extended radio component. Inverse Compton scattering of the synchrotron-emitting particles provides a possible interpretation of such a source. The presence of large-scale magnetic fields and particle acceleration due to the turbulent motion of galaxies through the intergalactic medium is discussed in relationship to the observed peculiarities of the galaxies found in this region.

Gavazzi, G.↗
NASA NTRS1985

The electron spectra in the synchrotron nebula of the supernova remnant G 29.7-0.3

EXOSAT results obtained with the imaging instrument (CMA) and the medium energy proportional counters (ME) are discussed. Assuming that the featureless power-law spectrum obtained in the 2 to 10 keV range is synchrotron radiation from relativistic electrons, one derives constraints on magnetic field strength and age of the nebula. The energy spectra of the electrons responsible for the emission in the radio and X-ray ranges are discussed. The great similarity of the physical properties of G 29.7-0.3 and of three synchrotron nebulae containing a compact object observed to pulse in X-rays makes G 29.7 - 0.3 a very promising candidate for further search for pulsed emission. Further observations at infrared wavelengths might reveal the break(s) in the emitted spectrum expected from the radio and X-ray power-law indices and give us more information on the production of the electron populations responsible for the emission of the nebula.

Koch-Miramond, L.↗
NASA NTRS1983

Rapid X-ray variability from the Seyfert 1 Galaxy NGC 4051

Strong variable X-ray emission from the nearby low luminosity Seyfert 1 galaxy NGC 4051 was discovered during observations with the imaging proportional counter of the Einstein Observatory. During one 2304 second observation, the X-ray flux more than doubled in an approximately linear fashion, and a 70% increase for 150 seconds was seen during another 968 second observation. Evidence is presented which demonstrates that the X-ray spectrum of NGC 4051 is unusually soft compared to Seyfert 1 galaxies or QSOs. The emission mechanism is probably not synchrotron or synchrotron self-Compton, but the emission can be plausibly explained by various black hole accretion models.

Marshall, F. E.↗
NASA NTRS1983

Rapid X-ray variability from the Seyfert 1 galaxy NGC 4051

Strong variable X-ray emission from the nearby low luminosity Seyfert 1 galaxy NGC 4051 was discovered during observations with the imaging proportional counter of the Einstein Observatory. During one 2304 second observation, the X-ray flux more than doubled in an approximately linear fashion, and a 70 percent increase for 150 seconds was seen during another 968 second observation. Evidence is presented which demonstrates that the X-ray spectrum of NGC 4051 is unusually soft compared to Seyfert 1 galaxies or QSOs. The emission mechanism is probably not synchrotron or synchrotron self-Compton, but the emission can be plausibly explained by various black hole accretion models. Previously announced in STAR as N83-23265

Marshall, F. E.↗
NASA NTRS1980

X-ray spectra of supernova remnants

The X-ray spectra of supernova remnants are discussed, and their implications for the emission mechanism are considered. A model-fitting procedure for analyzing spectral information is presented, and alternative data presentations are indicated. Model spectra expected from diffuse X-ray sources, in which X-ray transfer effects are minimized, are calculated for the cases of Compton interactions, synchrotron radiation and bremsstrahlung. The emission mechanisms of supernova remnants are then considered, and it is pointed out that whereas it is certain that the X radiation from the Crab pulsar arises from synchrotron emission, the kinetic mechanisms giving rise to X-ray emission in the nonpulsar SNRs are not understood. Results of Einstein Observatory solid state spectrometer measurements of the Cas A, Tycho and Puppis A are then presented which are fit by two-temperature thermal spectra, and the Crab SNR, fit by a power-law model. Spectral trends in the older and younger SNRs are pointed out, and the role of Einstein imaging data in future detailed modeling necessary to convert apparent abundances into true abundances is indicated.

Holt, S. S.↗
NASA NTRS1981

The X-ray structure of Centaurus A

The Einstein X-ray observatory imaging detectors have found X-ray emission associated with several components of the nearby radio galaxy Cen A = NGC 5128: (1) the compact nucleus; (2) an X-ray jet pointed toward the NE radio lobes; (3) the middle NE radio lobe; (4) the disk or dust lane; and (5) diffuse emission extending several arcmin around the nucleus. The intensity of the nucleus changed by a factor of seven over six months. The X-ray jet is considered in terms of thermal, inverse Compton, and synchrotron models. The emission of the NE radio lobe is greater than that expected from inverse Compton or synchrotron processes. Two ridges of emission are found along each edge of the dust lane, within several arcmin of the nucleus. The diffuse X-ray component has a luminosity which is too high to be due to bulge population X-ray sources, but which may be produced by main sequence stars under appropriate circumstances.

Feigelson, E. D.↗
NASA NTRS1980

X-ray studies of quasars and active galaxies with the Einstein Observatory

Preliminary results of the first six months of an X-ray survey of active galaxies and quasars performed with the imaging proportional counter on board the Einstein Observatory are presented. Consideration is given to detections of Seyfert galaxies, N galaxies, BL Lac objects and quasars, and properties of selected representative objects are discussed in detail. The statistical properties, including class averages and correlation coefficients, of the various X-ray active galaxies are calculated in an attempt to determine the relation of X-ray properties to the similarities and differences between the various classes of galaxies. Evidence is obtained for a continuity of high-energy behavior among all active galaxies, and it is noted that they all exhibit flux variability, often on a short time scale. The soft X-ray emission can be explained in terms of the synchrotron self-Compton model, or alternatively by thermal emission from hot gas. A significant correlation is obtained between the X-ray and optical fluxes for all objects considered, indicating that optical quasar counts may be used to infer the contribution of quasars to the diffuse X-ray background.

Ku, W. H.-M.↗
NASA NTRS1983

The X-ray spectra of the BL Lacertae objects PKS 0548 - 322 and 3C 66A

Einstein Observatory simultaneous imaging proportional counter and monitor proportional counter data are combined in order to derive the energy spectra of the BL Lac objects PKS 0548-322 and 3C 66A between 0.2 and 10 keV. While the latter is found to be variable in both intensity and spectral shape, the former, although constant in the present data, is found to have experienced a spectrum variation in view of results from other experiments. Attention is given to the implications of flux and spectral variability in BL Lac objects for models of X-ray emission mechanisms. It is suggested that the wide spread of the spectral index distribution is due to the detection of the highly variable synchrotron-produced X-rays that are generally undetected in QSOs.

Maccacaro, T.↗
NASA NTRS1980

Diffuse X-ray emission from the jets of SS 433

The detection of large-scale diffuse X-ray jets from the variable-emission-line object SS 433 is reported. Observations were made with the high resolution imager and imaging proportional counter on board the Einstein X-ray Observatory. The two diffuse X-ray features discovered are found to be aligned with both the central source of SS 433 and with the bulges of the shell of the huge supernova remnant W 50 associated with SS 433, thus confirming the detection of jets related to SS 433 and the link between SS 433 and W 50, establishing a minimum age of 1000 years for the jet phenomenon and offering an explanation of the size of W 50. Processes by which two oppositely directed beams of material from the SS 433 source region may emit the diffuse X-rays are then considered, including shock heating by interactions with the ambient medium and synchrotron radiation. Similarities between the morphologies of the diffuse X-ray emission and those of radio galaxies are also noted.

Seward, F.↗
NASA NTRS1983

X-ray observations of 20 3CR radio galaxies and their environs

X-ray observations of 20 3CR radio galaxies using the Imaging Proportional Counter on the Einstein Observatory are reported. Fourteen of the 18 galaxies, plus two sources without optical identification, are detected with soft X-ray luminosities (Lx) ranging from 10 to the 40.9th to 10 to the 44.4th ergs/s. In four of the galaxies there is evidence for extended X-ray structure. Lx is statistically correlated with the radio power of the core, the lobe radio power (especially below 1 GHz), and the steepness of the lobe radio spectrum at high frequencies. The complex interrelations between X-ray luminosities and radio core, radio lobe, optical nuclei, and galaxy clustering are examined; and it is found that a cluster origin of the X-rays provides the best explanation of these effects. Constraints on synchrotron and inverse Compton production of X-rays in radio lobes and on mechanisms of lobe confinement are also discussed.

Feigelson, E. D.↗