Large-area soft X-ray imaging system
System consists of large-area focusing collector and position sensitive proportional counter. Device can be used to study plasmas, with X-ray imaging in biological sciences, and crystallography.
Gorenstein, P.↗
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Results for “large area”
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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Accuracy assessment in the Large Area Crop Inventory Experiment
The Accuracy Assessment System (AAS) of the Large Area Crop Inventory Experiment (LACIE) was responsible for determining the accuracy and reliability of LACIE estimates of wheat production, area, and yield, made at regular intervals throughout the crop season, and for investigating the various LACIE error sources, quantifying these errors, and relating them to their causes. Some results of using the AAS during the three years of LACIE are reviewed. As the program culminated, AAS was able not only to meet the goal of obtaining accurate statistical estimates of sampling and classification accuracy, but also the goal of evaluating component labeling errors. Furthermore, the ground-truth data processing matured from collecting data for one crop (small grains) to collecting, quality-checking, and archiving data for all crops in a LACIE small segment.
Houston, A. G.↗
The Gamma-ray Large Area Space Telescope (GLAST) Mission Concept Study
The Gamma-ray Large Area Space Telescope (GLAST), a next generation high-energy gamma-ray mission designed to observe cosmic sources of gamma-rays over the approximate energy range from 10 MeV to 300 GeV, was studied for possible flight in the next decade. The GLAST baseline mission studied will achieve a major advance in sensitivity beyond EGRET by the use of modern particle physics tracking technology. The baseline instrument design that has been extensively studied uses solid-state silicon strip detectors for particle tracking and efficient on-board data processing and event triggering to achieve more than an order of magnitude improvement in sensitivity compared to EGRET. Development of technology requirements and a technology development roadmap for the GLAST mission is presented.
Michelson, Peter F.↗
Optical Distortion Evaluation in Large Area Windows using Interferometry
It is important that imagery seen through large area windows, such as those used on space vehicles, not be substantially distorted. Many approaches are described in the literature for measuring the distortion of an optical window, but most suffer from either poor resolution or processing difficulties. In this paper a new definition of distortion is presented, allowing accurate measurement using an optical interferometer. This new definition is shown to be equivalent to the definitions provided by the military and the standards organizations. In order to determine the advantages and disadvantages of this new approach the distortion of an acrylic window is measured using three different methods; image comparison, Moiré interferometry, and phase-shifting interferometry.
Interferometer↗
Development of the Model of Galactic Interstellar Emission for Standard Point-Source Analysis of Fermi Large Area Telescope Data
Most of the celestial gamma rays detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons. Conventional point-source and extended-source studies rely on the modeling of this diffuse emission for accurate characterization. Here, we describe the development of the Galactic Interstellar Emission Model (GIEM),which is the standard adopted by the LAT Collaboration and is publicly available. This model is based on a linear combination of maps for interstellar gas column density in Galactocentric annuli and for the inverse-Compton emission produced in the Galaxy. In the GIEM, we also include large-scale structures like Loop I and the Fermi bubbles. The measured gas emissivity spectra confirm that the cosmic-ray proton density decreases with Galactocentric distance beyond 5 kpc from the Galactic Center. The measurements also suggest a softening of the proton spectrum with Galactocentric distance. We observe that the Fermi bubbles have boundaries with a shape similar to a catenary at latitudes below 20deg and we observe an enhanced emission toward their base extending in the north and south Galactic directions and located within approximately 4deg of the Galactic Center.
gamma rays: diffuse background – gamma rays: gen↗
Parametric study of the performance characteristics and weight variations of large-area roll-up solar arrays
Performance characteristics and weight variations of large area, roll-up, solar arrays
Coyner, J. V., Jr.↗
Optimization of large area solar cells for low cost space application
The development of large-area solar cell manufacturing techniques for production of up to 10 kW/month of cells for use on the Shuttle Power Extension Package is detailed. Design goals for the cells were 14% efficiency at 135.3 mW/sq cm AM0 illumination for a 10 ohm-cm BSF/reflector cell, or 12.8% for a 2 ohm-cm BSR cell. Use of terrestrial cell technology to produce CVD SiO2 dielectric insulators for 3-in. ingot cells yielded satisfactory contact integrity. Fused silica coverings with thicknesses of 0.004 in. have allowed exploration of conventional and wraparound cell configurations due to inherent flexibilities of the frosted covers. One production run can now handle 108 3-in. wafers for the wraparound form or 216 in one-sided contact evaporations, with both processes taking 70 mins. Current contact grid designs for space use production permits average efficiencies of 12.8%.
Matthei, K. W.↗
High Energy Astrophysics with the Fermi Large Area Telescope
This slide presentation reviews some of the findings of the Large Area Telescope (LAT) aboard the Fermi Observatory. It includes information about the LAT, and the Gamma-Ray Burst Monitor (GBM), detection of the quiet sun and the moon in gamma rays, Pulsars observed by the observatory, Globular Star Clusters, Active Galactic Nucleus, and Gamma-Ray Bursts, with specific information about GRB 080916C.
Hays, Elizabeth↗
Image intensifier photography of simulated showers in large area layers of plastic scintillators
Image intensifier photography of simulated showers in large-area of plastic scintillator
Huggett, R. W.↗
The Large Area Crop Inventory Experiment /LACIE/ - An assessment after one year of operation
A Large Area Crop Inventory Experiment (LACIE) has been undertaken jointly by the U.S. Department of Agriculture (USDA), the National Oceanic and Atmospheric Administration (NOAA) of the Department of Commerce and the National Aeronautics and Space Administration (NASA) to prove out an economically important application of remote sensing from space. The first phase of the Experiment, which focused upon determinations of wheat area in the U.S. Great Plains and upon the development and testing of yield models, is now nearing completion. The system implemented to handle and analyze the Landsat and meteorological data has generally worked well and met operational goals. A very preliminary assessment of results to date indicates that the accuracy goals of the experiment can be met.
Macdonald, R. B.↗
Large Area Crop Inventory Experiment (LACIE). Phase 1: Evaluation report
It appears that the Large Area Crop Inventory Experiment over the Great Plains, can with a reasonable expectation, be a satisfactory component of a 90/90 production estimator. The area estimator produced more accurate area estimates for the total winter wheat region than for the mixed spring and winter wheat region of the northern Great Plains. The accuracy does appear to degrade somewhat in regions of marginal agriculture where there are small fields and abundant confusion crops. However, it would appear that these regions tend also to be marginal with respect to wheat production and thus increased area estimation errors do not greatly influence the overall production estimation accuracy in the United States. The loss of segments resulting from cloud cover appears to be a random phenomenon that introduces no significant bias into the estimates. This loss does increase the variance of the estimates.
Source record↗
A large-area gas scintillation proportional counter for X-ray astronomy
An improved large-area gas scintillation proportional counter has been built, suitable for use in X-ray astronomy. This counter employs electron focusing in a drift region to achieve uniform response. It is shown that a spectral resolution of 9.1% FWHM at 5.9 keV can be obtained over a useful area of 100 sq cm. It is demonstrated that signal rise-time discrimination can be used to reject non-X-ray background as efficiently as in ordinary proportional counters.
Anderson, D. F.↗
The Fermi Large Area Telescope on Orbit: Event Classification, Instrument Response Functions, and Calibration
The Fermi Large Area Telescope (Fermi-LAT, hereafter LAT), the primary instrument on the Fermi Gamma-ray Space Telescope (Fermi) mission, is an imaging, wide field-of-view, high-energy -ray telescope, covering the energy range from 20 MeV to more than 300 GeV. During the first years of the mission the LAT team has gained considerable insight into the in-flight performance of the instrument. Accordingly, we have updated the analysis used to reduce LAT data for public release as well as the Instrument Response Functions (IRFs), the description of the instrument performance provided for data analysis. In this paper we describe the effects that motivated these updates. Furthermore, we discuss how we originally derived IRFs from Monte Carlo simulations and later corrected those IRFs for discrepancies observed between flight and simulated data. We also give details of the validations performed using flight data and quantify the residual uncertainties in the IRFs. Finally, we describe techniques the LAT team has developed to propagate those uncertainties into estimates of the systematic errors on common measurements such as fluxes and spectra of astrophysical sources.
Ackermann, M.↗
A technology program for large area space systems
The large space systems technology program (LSST) is discussed. The purpose of LSST is to define and develop technology for large space systems and associated subsystems required for projected NASA space missions. Goals involving structural concepts and supporting technology are surveyed. The application of LSST to the design of the solar power satellite is considered.
Guastaferro, A.↗
Large area low-cost space solar cell development
A development program to produce large-area (5.9 x 5.9 cm) space quality silicon solar cells with a cost goal of 30 $/watt is descibed. Five cell types under investigation include wraparound dielectric, mechanical wraparound and conventional contact configurations with combinations of 2 or 10 ohm-cm resistivity, back surface reflectors and/or fields, and diffused or ion implanted junctions. A single step process to cut cell and cover-glass simultaneously is being developed. A description of cell developments by Applied Solar Energy Corp., Spectrolab and Spire is included. Results are given for cell and array tests, performed by Lockheed, TRW and NASA. Future large solar arrays that might use cells of this type are discussed.
Baraona, C. R.↗
On bonding large area silicon wafers Final report
Bonding techniques, stress analysis, and bond properties for large-area silicon wafers
Source record↗
Development of a Thick-film Silicon Ribbon Growth Technique for Application to Large-area Solar Cells and Arrays
A new technique is described for growth of large-area silicon ribbons. This technique is an edge-defined, film-fed growth process by which single crystals can be grown having a shape controlled by the outside dimensions of a shaping die, growth taking place from an extremely thin film of liquid fed by capillary action from a crucible below. The material from which the die is fabricated is very critical to the process. The die must be wet by the silicon, but adverse impurities must not be introduced into the silicon, and the die must not become degraded by the molten silicon. A breakthrough in die fabrication that has allowed the growth of silicon ribbons having dimensions of 1 cm by 30 cm with a thickness of 0.7 mm is described. The implications of this significant advancement with respect to development of photovoltaic solar arrays for wide-scale terrestrial solar-to-electric energy conversion systems are discussed.
Berman, P. A.↗
A large-area lithium-fluoride Bragg spectrometer for stellar X-ray astronomy
A large-area Bragg spectrometer used to search for the Fe XXV X-ray emission lines of Sco X-1 is described. The device has 3400 sq cm of LiF on nine crystal panels aligned perpendicular to the longitudinal axis of the rocket. X rays satisfying the Bragg condition reflect into an array of nine companion proportional counters. A pointing system incorporating a free gyroscope with 2 degrees of freedom assures that target X rays are reflected at the required angle and produces repeated spectral scans of the X-ray continuum, which are later superimposed to correct temporal effects. The instrument is capable of detecting a narrow line flux from Sco X-1 of about .01 photons/sq cm/sec.
Stockman, H. S., Jr.↗