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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Diffraction gratings with two-orders-of-magnitude-enhanced dispersion rates for sub-meV resolution soft X-ray spectroscopy

Diffraction gratings with large angular dispersion rates are central to obtaining high spectral resolution in grating spectrometers operating over a broad spectral range from infrared to soft X-ray domains. The greatest challenge is of course to achieve large dispersion rates in the short-wavelength X-ray domain. Here it is shown that crystals in non-coplanar asymmetric X-ray Bragg diffraction can function as high-reflectance broadband soft X-ray diffraction gratings with dispersion rates that are at least two orders of magnitude larger than those that are possible with state-of-the-art man-made gratings. Additionally, this opens new opportunities to design and implement soft X-ray resonant inelastic scattering (RIXS) spectrometers with spectral resolutions that are up to two orders of magnitude higher than what is currently possible, to further advance a very dynamic field of RIXS spectroscopy, and to make it competitive with inelastic neutron scattering. Examples of large-dispersion-rate crystal diffraction gratings operating near the 930 eV L 3 absorption edge in Cu and of the 2.838 keV L 3 -edge in Ru are presented.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1988

X-ray performance of the LAMAR protoflight mirror

A grazing incidence X-ray mirror in the Kirkpatrick-Baez geometry was constructed and tested. Its geometric aperture measures 20 by 30 cm and its length is 100 cm. The focal length is 3.4 m measured from the front to the focal plane. It is the first of eight mirrors to be built for the LAMAR experiment of the Shuttle High Energy Astrophysics Laboratory. Its angular resolution was measured at 1.5 and 6.4 keV in a quasi-parallel X-ray beam at the Marshall Space Flight Center. The half-power width (HPW) of the resolution function projectd along a horizontal axis is 31-sec of arc at both energies and in visible light. With the addition of small isolation pads the mirror is able to withstand the vibration and acceleration levels of a Space Shuttle launch. The resolution remains under 35-sec of arc HPW for changes in temperature of 9.5 C and when a modest temperature gradient is imposed on the mirror.

Fabricant, Daniel G.↗
NASA NTRS2012

Observations of the Crab Nebula with the Chandra X-Ray Observatory

The Crab Nebula and its pulsar has been the subject of a number of detailed observations with the Chandra X-ray Observatory. The superb angular resolution of Chandra s high-resolution telescope has made possible numerous remarkable results. Here we describe a number of specific studies of the Crab that I and my colleagues have undertaken. We discuss the geometry of the system, which indicates that the "inner X-ray ring", typically identified with the termination shock of the pulsar s particle wind, is most likely not in the equatorial plane of the pulsar. Other topics are the northern wisps and their evolution with time; the characterization of features in the jet to the southeast; pulse-phase spectroscopy and possible correlations with the features at other wavelengths, particularly the optical polarization; and a search for correlations of the X-ray flux with the recently-discovered gamma -ray flares.

Weisskopf, Martin C.↗
NASA NTRS2011

The Advanced Energetic Pair Telescope (AdEPT}: A Future Medium-Energy Gamma-Ray Balloon (and Explorer?) Mission

Gamma-ray astrophysics probes the highest energy, exotic phenomena in astrophysics. In the medium-energy regime, 0.1-200 MeV, many astrophysical objects exhibit unique and transitory behavior such as the transition from electron dominated to hadron dominated processes, spectral breaks, bursts, and flares. Medium-energy gamma-ray imaging however, continues to be a major challenge particularly because of high background, low effective area, and low source intensities. The sensitivity and angular resolution required to address these challenges requires a leap in technology. The Advance Energetic Pair Telescope (AdEPT) being developed at GSFC is designed to image gamma rays above 5 MeV via pair production with angular resolution of 1-10 deg. In addition AdEPT will, for the first time, provide high polarization sensitivity in this energy range. This performance is achieved by reducing the effective area in favor of enhanced angular resolution through the use of a low-density gaseous conversion medium. AdEPT is based on the Three-Dimensional Track Imager (3-DTI) technology that combines a large volume Negative Ion Time Projection Chamber (NITPC) with 2-D Micro-Well Detector (MWD) readout. I will review the major science topics addressable with medium-energy gamma-rays and discuss the current status of the AdEPT technology, a proposed balloon instrument, and the design of a future satellite mission.

Hunter, Stanley D.↗
NASA NTRS1983

Nuclear Science Symposium, 29th, and Symposium on Nuclear Power, 14th, Washington, DC, October 20-22, 1982, Proceedings

High-energy radiation detectors suitable for balloon-borne or space-based radiation event studies are described. The employment of NaI(Tl) scintillator bars for gamma ray detection is outlined, and the development of a fluorescent gated gas-filled scintillation proportional counter is reported. A high throughput nondispersive hard X ray spectrograph with angular resolution for cosmic bursts, transients, and sources has been constructed. Features of a sealed high pressure xenon filled imaging proportional counter with a 30 sq cm sensitive area are explored. Finally, the various radiation effects on electronic circuitry in a space environment are defined, and an MOS dosimeter for assaying the cumulative radiation flux in a spacecraft due to ambient conditions is characterized.

Davis, W. D.↗
NASA NTRS2003

A New Method to Resolve X-Ray Halos around Point Sources with Chandra Data and Its Application to Cygnus X-1

With excellent angular resolution, good energy resolution, and a broad energy band, the Chandra Advanced CCD Imaging Spectrometer (ACIS) is the best instrument for studying the X-ray halos around some Galactic X-ray point sources caused by the dust scattering of X-rays in the interstellar medium. However, the direct images of bright sources obtained with the ACIS usually suffer from severe pileup. Making use of the fact that an isotropic image could be reconstructed from its projection in to any direction, we can reconstruct the images of the X-ray halos from the data obtained with the High Energy Transition Grating Spectrometer (HETGS) and/or in continuos clocking (CC) mode. These data have no or less serious pileup and enable us to take full advantage of the excellent angular resolution of Chandra. With the reconstructed high-resolution images, we can probe the X-ray halos as close as 1" to their associated point sources. Applying this method to Cygnus X-1 observed with the Chandra HETGS in CC mode, we derived an energy-dependent radial halo flux distribution and concluded that in a circular region (2' in radius) centered a the point source: (1) relative to the total intensity, the fractional halo intensity is about 15% at keV and drops to aboout 5% at approximately 6 keV (2) about 50% of the halo photons are within the region of a radius less than 40 inches and (3) the spectrum of the pooint source is slightly distorted by the halo contamination.

Yao, Yangsen↗
NASA NTRS1993

An atlas of high-resolution IRAS maps on nearby galaxies

An atlas of far-infrared IRAS maps with near 1 arcmin angular resolution of 30 optically large galaxies is presented. The high-resolution IRAS maps were produced with the Maximum Correlation Method (MCM) image construction and enhancement technique developed at IPAC. The MCM technique, which recovers the spatial information contained in the overlapping detector data samples of the IRAS all-sky survey scans, is outlined and tests to verify the structural reliability and photometric integrity of the high-resolution maps are presented. The infrared structure revealed in individual galaxies is discussed. The atlas complements the IRAS Nearby Galaxy High-Resolution Image Atlas, the high-resolution galaxy images encoded in FITS format, which is provided to the astronomical community as an IPAC product.

Rice, Walter↗
NASA NTRS1990

Aperture synthesis CO observations of the inner disk of NGC 1068

NGC 1068 is probably the nearest galaxy with both a high rate of star formation and a high luminosity active nucleus. About one-half of the total IR luminosity originates in a disk approximately 30 seconds in size, which has been taken as evidence for a high rate of massive star formation (Telesco et al. 1984). Previous CO line observations have shown the existence of a ring at the outer boundary of the inner disk (Myers and Scoville 1987). Although these observations have proved that this ring is extremely rich in molecular gas (as suggested by Scoville et al. 1983), the angular resolution (approx. 6 seconds) was not high enough to resolve its structure. New aperture synthesis observations of the CO (J=1 to 0) emission in the inner disk of NGC 1068 have been carried out with the Owens Valley Radio Observatory (OVRO) mm Interferometer. The new receivers installed for the 88/89 season have allowed researchers to obtain a high sensitivity map of the CO emission. The molecular cloud ring has been resolved and continuum as well as line emission from the nucleus of the galaxy have been detected.

Planesas, P.↗
NASA NTRS1972

Gamma-neutrino angular correlations in muon capture.

Using a high-resolution Ge(Li) spectrometer, it proved possible to observe several Doppler-broadened gamma-ray transitions in Al-28 excited by muon capture in Si-28. Several of these transitions are shown to be suitable for analysis in terms of angular correlations between the neutrino and a deexcitation nuclear gamma-ray. The observed transitions are interpreted in terms of gamma-neutrino correlation coefficients which are functions of the weak-interaction coupling constants.

Miller, G. H.↗
NASA NTRS2011

Designing the Balloon Experimental Twin Telescope for Infrared Interferometry

While infrared astronomy has revolutionized our understanding of galaxies, stars, and planets, further progress on major questions is stymied by the inescapable fact that the spatial resolution of single-aperture telescopes degrades at long wavelengths. The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is an 8-meter boom interferometer to operate in the FIR (30-90 micron) on a high altitude balloon. The long baseline will provide unprecedented angular resolution (approx. 5") in this band. In order for BETTII to be successful, the gondola must be designed carefully to provide a high level of stability with optics designed to send a collimated beam into the cryogenic instrument. We present results from the first 5 months of design effort for BETTII. Over this short period of time, we have made significant progress and are on track to complete the design of BETTII during this year.

Rinehart, Stephen↗
NASA NTRS2019

New Mission Concept: Investigation of the Galactic Center with the Galactic Center Explorer (GalCenEx)

The European Space Observatory INTEGRAL has been providing excellent results on X-ray and γ–ray astronomy since its launch in 2002. Among the most important results are the spectroscopy and imaging measurements of celestial γ-ray sources, including mapping the 511 keV radiation from the Galactic plane. However, the nature of the 511 keV positron annihilation line around the Galactic Center region is still a mystery. Similarly, the structure and nature of the Galactic Center supermassive black hole and its surroundings, as well as the structure of heavily populated sky regions such as Cygnus and Carina in γ-rays, remain unclear. We present a concept of a potential next-generation γ-ray telescope with the major science objectives: a) solve the mystery of the Galactic Center region 511 keV positron annihilation line by mapping the Galactic Center region with high energy (<1% FWHM) and angular (< 10 arcmin) resolution and with line sensitivity <10-5 ph cm-2 s-1; b) understand the nature of the Galactic Center supermassive black hole environment by creating a high-resolution spectral and intensity map of the surrounding region in 0.1 – 20 MeV γ rays; and c) explore Galactic chemical evolution and sites of explosive element synthesis by conducting high-sensitivity measurements of nuclear lines from Type 1a supernovae and other objects. The instrument is based on a novel high energy and position resolution CdZnTe Imager, coded aperture mask, and heavy-scintillator shield, and can be considered for a NASA Explorer mission.

Moiseev, Alexander↗
NASA NTRS1977

A hard X-ray imaging instrument for solar and cosmic sources

A hard X-ray imaging instrument is described which is capable of high-resolution imaging of solar and cosmic hard X-ray sources between 2 and 80 keV during Shuttle sortie flights. The properties of solar burst sources and the resulting instrument requirements are discussed. The instrument envelope of 1.2 x 1.2 x 3.0 meters includes a tungsten multigrid collimator which has 4-arcsec resolution, a 40-arcmin response envelope and a point-source effective area of 26 sq cm. A combination of periodic fan beams and nonperiodic pencil beams enables a unique deconvolution to be achieved within a 128 x 128 arcsec field without mechanical scanning. The detector system is a set of direct-readout 40 atm-cm xenon-filled proportional counters designed to minimize background. The instrument is capable of refurbishment to optimize the collimator configuration for specific solar or cosmic scientific objectives, to upgrade the angular resolution, or to extend the high-energy response.

Hurford, G. J.↗
NASA NTRS1985

The angular resolution of air shower gamma ray telescopes

A crucial charactristic of air shower arrays in the field of high energy gamma-ray astronomy is their angular resolving power, the arrival directions being obtained by the time of flight measurements. A small air shower array-telescope is used to study the resolution in the definition of the shower front as a function of the shower size.

Morello, C.↗
DOE OSTI2021

First 3D vector tracking of helium recoils for fast neutron measurements at Super$\mathrm{KEKB}$

Here we present results from the first deployment of novel, high definition, compact gas Time Projection Chambers (TPCs) with pixel chip readout as part of the BEAST II beam background measurement project at SuperKEKB. The TPCs provide detailed 3D imaging of ionization from neutron-induced nuclear recoils in a helium and carbon dioxide target gas mixture at standard temperature and pressure. We present the TPC performance and the neutron backgrounds observed during the initial stage of collider commissioning. We find excellent electron background rejection, leading to background-free nuclear recoil measurements above 50 keV ee , despite the extreme high-background environment. We measure an angular resolution better than 20° for recoil tracks longer than 1.7 mm, corresponding to an average ionization energy of approximately 100 keV ee . We also obtain the full 3D vector direction of helium recoils by utilizing charge profile measurements along the recoil axis, with a correct head/tail assignment efficiency of approximately 80%. With this performance, we present comparisons between measured and simulated event rates, recoil energy spectra, and directional distributions originating from beam–gas and Touschek beam losses at SuperKEKB. We utilize head/tail recognition to distinguish neutron components traveling with positive radial velocity in the Belle II coordinate system from those traveling in the opposite direction. Finally, we present a novel method of discriminating beam–gas interactions from Touschek beam losses that can eliminate the need for dedicated accelerator runs for background measurements. This method is still statistics-limited. However, future studies should be able to verify this method, which in turn could lead to neutron background analysis runs symbiotic with normal Belle II operation. The capabilities demonstrated here also suggest that high definition recoil imaging in gas TPCs is applicable to low energy, low-background experiments, such as directional dark matter searches.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2026

Visualization of Thermal and Strain Dynamics in X-ray Optics by Time-Resolved Rocking Curve Imaging

The absorption of intense X-ray pulses from free-electron lasers by X-ray crystal optics triggers rapid thermal and mechanical responses, including lattice compression, expan- sion, and strain-wave propagation, which dynamically modify diffraction conditions and wavefront properties. These effects pose significant challenges for next-generation high- repetition-rate X-ray sources, particularly for crystal monochromators used in XFEL beam- lines and self-seeding. Here, we demonstrate time-resolved rocking curve imaging (TrRCI) of X-ray Bragg optics with high spatial resolution (6.4 μm) and sub-1-μrad angular resolu- tion, enabling direct visualization of lattice dynamics from nanoseconds to microseconds. By combining a high-flux beamline at SPring-8, a scintillator-coupled sCMOS detector, and a synchronized femtosecond laser system, we capture lattice dynamics induced by tran- sient laser heating with a strain sensitivity on the order of 10−6 . Our results reveal transient lattice deformation and the propagation of laser-induced strain waves over millimeter-scale distances. This approach provides experimental benchmarks for understanding heat-load effects in high-repetition-rate X-ray optics.

Source record↗
NASA NTRS1990

Processing and analysis of radiometer measurements for airborne reconnaissance

This paper describes selected results of airborne, radiometric imaging measurements at 90 GHz and 140 GHz relevant for the application in reconnaissance. Using a temperature resolution below 0.5 K and an angular resolution of about 1-degree high-quality images show the capability of discriminating between many brightness temperature classes within our natural environment and man-made objects. Measurement examples are given for cloud and fog penetration at 90 GHz, for the detection of vehicles on roads, and for the detection and classification of airports and airplanes. The application of different contour enhancement methods (Marr-Hildreth and Canny) shows the possibility of extracting lines and shapes precisely in order to improve automatic target recognition. The registration of the passive images with corresponding X-band synthetic aperture images from the same area is carried out and the high degree of correlation is discussed.

Suess, Helmut↗
NASA NTRS2015

The X-Ray Surveyor Mission: A Concept Study

NASA's Chandra X-ray Observatory continues to provide an unparalleled means for exploring the high-energy universe. With its half-arcsecond angular resolution, Chandra studies have deepened our understanding of galaxy clusters, active galactic nuclei, galaxies, supernova remnants, neutron stars, black holes, and solar system objects. As we look beyond Chandra, it is clear that comparable or even better angular resolution with greatly increased photon throughput is essential to address ever more demanding science questions-such as the formation and growth of black hole seeds at very high redshifts; the emergence of the first galaxy groups; and details of feedback over a large range of scales from galaxies to galaxy clusters. Recently, we initiated a concept study for such a mission, dubbed X-ray Surveyor. The X-ray Surveyor strawman payload is comprised of a high-resolution mirror assembly and an instrument set, which may include an X-ray microcalorimeter, a high-definition imager, and a dispersive grating spectrometer and its readout. The mirror assembly will consist of highly nested, thin, grazing-incidence mirrors, for which a number of technical approaches are currently under development-including adjustable X-ray optics, differential deposition, and new polishing techniques applied to a variety of substrates. This study benefits from previous studies of large missions carried out over the past two decades and, in most areas, points to mission requirements no more stringent than those of Chandra.

Astronomy↗