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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 235 records · Page 13
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NASA NTRS1981

Observations of interplanetary energetic charged particles from gamma-ray line solar flares

Observations of interplanetary energetic ions from the 7 June, 21 June and 1 July 1980 gamma ray line solar flares are presented. The observations are from the Max-Planck-Institut/University of Maryland Ultra Low Energy Wide Angle Telescope aboard the ISEE-3 spacecraft. Both June flares produced relatively low intensity proton events at earth with peak intensities at 10-20 MeV approximately 5 x .01 protons square cm sec sr MeV)-1. Neither flare showed evidence of being enriched in either 3He or Fe at approximately 1 MeV/nucleon. The 1 July flare produced no observable ion or electron enhancements.

Pesses, M. E.↗
NASA NTRS1981

A new method for focusing and imaging X-rays and gamma-rays with diffraction crystals

Bent diffraction crystals in which the intercrystalline-plane spacing is varied as a function of position in the crystal are used to focus monochromatic radiation from a point source or parallel beam down to a point image. Conversely, radiation from a point source can be focused into an outgoing parallel beam. The Bragg angle for diffraction of monochromatic radiation will now vary as a function of position in the crystal and this new degree of freedom is used to obtain focusing and imaging of the diffracted beam. This approach to focusing and imaging is applied to the design of a large-area, high resolution X-ray telescope that is also a high resolution monochromator with the unique feature that the width of the energy increment that is diffracted can be controlled and varied during the operation of the instrument. The field can be scanned with a wide energy increment and then switched to a narrow energy increment for the high resolution work. Both transmission and reflection type diffraction crystals can be used.

Smither, R. K.↗
NASA NTRS1981

Observations of interplanetary energetic charged particles from gamma-ray line solar flares

Results from ISEE-3 experiments on interplanetary energetic charged particles on June 7, June 21, and July 1, 1980 dealing with gamma ray producing solar flares are reported. The data were gathered by the Ultra Low Energy Wide Angle Telescope, which comprises a thin window, flow through proportional counter/solid-state detector composition telescope. Evidence of a specified time delay from an observed flare and the recording of 0.44-1.3 MeV electrons on ISEE-3 combined with quiescent periods of at least two hours before the observations and recording provides a link between the events. The data indicates interplanetary energetic particle enhancement, and a second, similar set of occurrences was also observed. Protons were accelerated up to 10-20 MeV. No enrichment of either He-3 or Fe was found.

Pesses, M. E.↗
NASA NTRS1983

Measurements of galactic plane gamma-ray emission in the energy range 10-80 MeV

A spark chamber gamma ray telescope was developed and flown to observe diffuse gamma ray emission from the central region of the galaxy. The extension of observations down to 10 MeV provides important new data indicating that the galactic diffuse gamma ray spectrum continues as a power law down to about 10 MeV, an observation in good agreement with recent theoretical predictions. Data from other experiments in the range from 100 keV to 10 MeV show a significant departure from the extension of the power-law fit to the medium energy observations reported here, possibly indicating that a different mechanism may be responsible for the emissions below and above a few MeV. The intensity of the spectrum above 10 MeV implies a galactic electron spectrum which is also very intense down to about 10 MeV. Electrons in this energy range cannot be observed in the solar cavity because of solar modulation effects. The galactic gamma ray data are compared with recent theoretical predictions. Previously announced in STAR as N83-17444

Bertsch, D. L.↗
NASA NTRS1982

A mercuric detector system for X-ray astronomy. 2. Results from flight tests of a balloon borne instrument

To establish the expected sensitivity of a new hard X-ray telescope design, an experiment was conducted to measure the background counting rate at balloon altitudes (40 km) of mercuric iodide, a room temperature solid state X-ray detector. The prototype detector consisted of two thin mercuric iodide (HgI2) detectors surrounded by a large bismuth germanate (Bi4Ge3O12) scintillator operated in anticoincidence. The bismuth germanate shield vetoed most of the background counting rate induced by atmospheric gamma-rays, neutrons and cosmic rays. A balloon-borne gondola containing a prototype detector assembly was designed, constructed and flown twice in the spring of 1982 from Palestine, Texas. The second flight of this instrument established a differential background counting rate of 4.2 O.7 x 10-5 counts/sec cm keV over the energy range of 40 to 80 keV. This measurement was within 50% of the predicted value. The measured rate is approx 5 times lower than previously achieved in shielded NaI/CsI or Ge systems operating in the same energy range. The prediction was based on a Monte Carlo simulation of the detector assembly in the radiation environment at float altitude.

Vallerga, J.↗
NASA NTRS1983

A mercuric iodide detector system for X-ray astronomy. II - Results from flight tests of a balloon borne instrument

To establish the expected sensitivity of a new hard X-ray telescope design, described by Ricker et al., an experiment was conducted to measure the background counting rate at balloon altitudes (40 km) of mercuric iodide, a room temperature solid state X-ray detector. The prototype detector consisted of two thin mercuric iodide (HgI2) detectors surrounded by a large bismuth germanate scintillator operated in anticoincidence. The bismuth germanate shield vetoed most of the background counting rate induced by atmospheric gamma-rays, neutrons and cosmic rays. A balloon-borne gondola containing a prototype detector assembly was designed, constructed and flown twice in the spring of 1982 from Palestine, TX. The second flight of this instrument established a differential background counting rate of 4.2 + or - 0.7 x 10 to the -5th counts/s sq cm keV over the energy range of 40-80 keV. This measurement was within 50 percent of the predicted value. The measured rate is about 5 times lower than previously achieved in shielded NaI/CsI or Ge systems operating in the same energy range.

Vallerga, J. V.↗
NASA NTRS1983

NASA astrophysics - Optical systems to explore the universe

Major and minor NASA astrophysical research efforts in the near-term are outlined, together with projections of direction for future projects. The Space Telescope is being readied for a 1986 launch and will feature an f/24, 2.4 m aperture, an MgF2 mirror with better than 1/60 wavelength accuracy and will be diffraction-limited in the UV. Pointing accuracy is designed to be 0.007 arcsec for 24 hr. Optical, spectrometric, and photometric equipment will be included. Around 1990, Shuttle-based missions will include an IR telescope and a subarcsec solar surface imaging device. A free-flying X-ray observatory (AXAF) is planned and will include a sensitivity that exceeds that of the HEAO-2 spacecraft by two orders of magnitude. Instruments are under development for higher resolution UV, gamma-ray, and IR studies. In-orbit interferometry is being studied and will depend on in-orbit assembly and servicing of stable structures with segmented optics.

Pellerin, C. J., Jr.↗
NASA NTRS1985

Constraints on the galactic distribution of cosmic rays from the COS-B gamma-ray data

The diffuse component of the galactic high energy gamma rays results mainly from the interaction of CR nuclei and electrons with the nuclei of the interstellar gas. An additional contribution is obtained from the interaction of CR electrons with the interstellar photons through the inverse-Compton (IC) process. Gamma ray astronomy therefore offers an excellent means to study the distribution of CR particles throughout the Galaxy, but it is essential to know the distribution of the target interstellar gas particles, the major constituents being atomic and molecular hydrogen. Large scale millimeter wave surveys of the CO molecule covering more than half of the Milky Way, obtained with the Columbia 1.2 m telescopes, are currently available and are used to trace the H2; the COS-B observations have sufficient resolution and sensitivity to constrain the relation between the integrated CO line intensity and the molecular hydrogen column density.

Bloemen, J. B. G. M.↗
NASA NTRS1985

A method to improve observations of gamma-ray sources near 10 (15) eV

Now that sources of gamma rays near 10 to the 15th power eV have been identified, there is a need for telescopes which can study in detail the high energy gamma ray emissions from these sources. The capabilities of a Cerenkov detector which can track a source at large zenith angle (small elevation angle) are analyzed. Because the observed showers must then develop far from the detector, the effective detection area is very large. During a single half-hour hot phase of Cygnus X-3, for example, it may be possible to detect 45 signal showers compared with 10 background showers. Time structure within the hot phase may then be discernible. The precise capabilities of the detector depend on its mirror size, angular acceptance, electronic speed, coincidence properties, etc. Calculations are presented for one feasible design using mirrors of an improved Fly's Eye type.

Sommers, P.↗
NASA NTRS1989

Solar flare gamma-ray and hard x ray imaging with the GRID-on-a-balloon

A primary scientific objective for solar flare research during the rapidly approaching maximum in solar activity is the imaging of gamma-ray and hard x ray sources of solar flare emissions. These goals will be pursued by the Gamma Ray Imaging Device (GRID) instrument, one of three instruments recently selected for NASA's Max '91 Solar Balloon Program. The GRID instrument is based on the technique of Fourier transform imaging and utilizes scanning modulation grid collimator optics to provide full-Sun imaging with 1.9-arcsecond resolution over the energy range from 20 to 700 keV at time resolutions from 0.1 to 2 s. The GRID telescope will employ 32 subcollimators, each composed of a matched pair of high-Z collimator grids separated by 5.2 meters and a phoswich scintillation spectrometer detector having no spatial resolution. The subcollimators and integrally-mounted fine aspect system are contained within a telescope canister which will be pointed to 0.1 degree accuracy and cyclically scanned to produce source modulation. The 32 subcollimators provide a uniform distribution of grid slit orientations and a logarithmic distribution of slit spacings corresponding to angular dimensions of 1.9 arcseconds to several arcminutes. The instrument is several orders of magnitude more sensitive than the HXIS instrument on the Solar Maximum Mission (SMM) and nearly 10 times more sensitive than any similar instrument scheduled to fly during the next solar maximum. The payload, designed for long-duration high-altitude balloon capability, is scheduled for its first science flight (8 to 14 days duration) from the Antarctic in January of 1992.

Orwig, Larry E.↗
NASA NTRS1991

Telescope Would Image X And Gamma Rays

Proposed telescope forms images of sources of gamma rays, hard x rays, and soft x rays. Contains reflecting, grazing-incidence reflectors. Multiple coaxial nested pairs used to form images simultaneously at multiple gamma-ray or hard x-ray energies or enhance collection area at single photon energy. Conceived for use in astrophysical studies in outer space. With modifications, used in terrestrial laboratory vaccum systems to image x or gamma rays from pulsed plasmas.

Hoover, Richard B.↗
NASA NTRS1991

The gamma-ray observatory

An overview is given of the Gamma Ray Observatory (GRO) mission. Detection of gamma rays and gamma ray sources, operations using the Space Shuttle, and instruments aboard the GRO, including the Burst and Transient Source Experiment (BATSE), the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET) are among the topics surveyed.

Source record↗
NASA NTRS1990

Catalog of SAS-2 gamma-ray observations (Fichtel, et al. 1990)

The machine-readable version of the catalog, as it is currently being distributed from the Astronomical Data Center, is described. The SAS-2 gamma ray catalog contains fluxes measured with the high energy gamma ray telescope flown aboard the second NASA Small Astronomy Satellite. The objects measured include various types of galaxies, quasi-stellar, and BL Lacertae objects, and pulsars. The catalog contains separate files for galaxies, pulsars, other objects, notes, and references.

Warren, Wayne H., Jr.↗
NASA NTRS1990

Space cryogenics from 1970 to 2010

While space-related cryogenic engineering in the 1950s and 1960s was primarily concerned with liquid fueled rocket fuel supply systems, the leading edge of technology development moved in the 1970s to the supply of 1.4-70 K cooling facilities for IR and gamma-ray astronomy instruments. Attention is presently given to the development history, current status, and future prospects for superfluid He cryocooling systems, in view of prospective requirements for micro-K cooling capacities over astronomical instrument service lives of the order of 10 years. The spacecraft in question will be launched in the mid-to-late 1990s and encompass the Advanced X-ray Astronomy facility, the Gyro Test of General Relativity, the Space IR Telescope Facility, Astromag, and the Submillimeter Explorer.

Mason, P.↗
NASA NTRS1990

Space astrophysics with large structures - CASES and P/OF

Space instruments for remote sensing, of the types used for astrophysics and solar-terrestrial physics among many disciplines, will grow to larger physical sizes in the future. The zero-g space environment does not inherently restrict such growth, because relatively lightweight structures can be used. Active servo control of the structures can greatly increase their size for a given mass. The Pinhole/Occulter Facility, a candidate Space Station attached payload, offers an example: it will achieve 0.2 arc s resolution by use of a 50-m baseline for coded-aperture telescopes for hard X-ray and gamma-ray imagers.

Hudson, Hugh S.↗
NASA NTRS1992

Cosmic ray albedo gamma rays from the quiet sun

We estimate the flux of gamma-rays that result from collisions of high energy galactic cosmic rays with the solar atmosphere. An important aspect of our model is the propagation of cosmic rays through the magnetic fields of the inner solar systems. We use diffusion to model propagation down to the bottom of the corona. Below the corona we trace particle orbits through the photospheric fields to determine the location of cosmic ray interactions in the solar atmosphere and evolve the resultant cascades. For our nominal choice of parameters, we predict an integrated flux of gamma rays (at 1 AU) of F(E(sub gamma) greater than 100 MeV) approximately = 5 x 10(exp -8)/sq cm sec. This can be an order of magnitude above the galactic background and should be observable by the Energetic Gamma Ray experiment telescope (EGRET).

Seckel, D.↗
NASA NTRS1991

The Solar-A mission - An overview

An overview of the Solar-A spacecraft, launched in August 1991, is presented. This mission is dedicated primarily to the study of solar flares, especially of high-energy phenomena observed in the X- and gamma-ray ranges. With a coordinated set of instruments, including hard X-ray and soft X-ray imaging telescopes as well as spectrometers with advanced capabilities, it is expected to reveal many new aspects of flares and help better understand their physics, supporting international collaboration with ground-based observatories as well as theoretical investigations. The scientific instruments of Solar-A, especially the soft X-ray telescope, require sophisticated control of flight operations to exploit their capabilities with the constraints of the telemetry data rate and the capacity of the data recorder; this is achieved by the 'data processor' unit. Objectives include flare-related phenomena, dynamical phenomena not necessarily related to flares, and global coronal structure.

Ogawara, Y.↗
NASA NTRS1990

EXOSS - A hard X-ray and soft gamma-ray astronomy mission

The Energetic X-ray Observatory on Space Station (EXOSS) is a mission concept for high-sensitivity coded-aperture sky surveys and studies of the spectral and temporal behavior of astrophysical sources from approximately 3 keV to 1 MeV. The scientific motivation for the mission and the instrument requirements, including the need for high angular resolution to resolve and identify numerous detectable sources, are summarized. Two baseline telescopes are described: one employing a 1.4-sq-m array of Xe gas imaging proportional counters to cover the 3 to 100 keV range with 1 arcmin resolution; the second using a 2.8-sq-m array of NaI/CsI imaging phoswich detectors to span the 20 keV to MeV range with 12 arcmin resolution.

Cook, W. R.↗