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NASA NTRS1976

Measurement of the primary cosmic electron spectrum from 10 to about 250 GeV

The intensity and energy spectrum of primary cosmic electrons from 10 to about 250 GeV have been studied by using balloon-borne detectors. The detectors were large-area ionization calorimeters which sampled showering particles frequently and demonstrated an energy resolution of about 7% in calibration tests. On one of the flights a time-of-flight system and detectors to sample the lateral properties of showers were used to examine and to test background rejection. The results of the balloon flights from Alamogordo, N. Mex., in 1970 and Cape Girardeau, Mo., in 1972 indicated that the primary cosmic ray electron differential energy spectrum exhibits no change of slope in the energy range measured and is well represented by a power law. The results indicate that the cosmic electron spectrum is steeper than the cosmic ray proton spectrum. It is shown that these data are consistent with the leakage lifetime model for the propagation of cosmic electrons in the galaxy, although other more complex models cannot be excluded on the basis of these data.

Silverberg, R. F.↗

NASA NTRS1976

Columbia University OSO-8 instrument for stellar and solar X-ray spectroscopy and polarimetry

A spectrometer and a polarimeter consisting of large-area panels of mosaic crystals have been constructed and prepared for use in the OSO-8 satellite. The instrumentation is planned for study of stellar and solar X-ray spectra between 1.8-8 keV and stellar X-ray polarization at 2.6 keV. Aspects of the design which enable the instrument to make measurements of the diverse range of stellar and solar phenomena are described. Some of the unique features, such as high sensitivity, high temporal resolution, and spectral range, are discussed. The applicability of the spectrometer and polarimeter to various current problems in X-ray astronomy is considered.

Wolff, R. S.↗

NASA NTRS1977

New process produces high-power Schottky diodes

Processing procedure using low-temperature platinum silicide, results in successful high-yield fabrication of large-area mesa-geometry Schottky diodes, with reverse breakdown voltages as high as 150 volts and leak currents less than 5 milliamps at 212 F.

Cordes, L. F.↗

NASA NTRS1976

Application of NASTRAN to large space structures

The application of NASTRAN to design studies of two very large-area lightweight structures is described. The first is the Satellite Solar Power Station, while the second is a deployable three hundred meter diameter antenna. A brief discussion of the operation of the SSPS is given, followed by a description of the structure. The use of the NASTRAN program for static, vibration and thermal analysis is illustrated and some results are given. Next, the deployable antenna is discussed and the use of NASTRAN for static analysis, buckling analysis and vibration analysis is detailed.

Balderes, T.↗

NASA NTRS1976

A backside illuminated 400 x 400 charge-coupled device imager

Large-area backside illuminated charge-coupled device imagers have been fabricated using double level aluminum transfer electrode technology. Devices with 100 x 160 and 400 x 400 resolution elements have been fabricated using buried channel technology for high charge transfer efficiency. Detailed optical characterization has been performed on these imagers over the temperature range -40 to +24 C and at several operating frequencies between 10 kHz and 1 MHz.

Antcliffe, G. A.↗

NASA NTRS1976

The graphite crystal X-ray spectrometer on OSO-8

The large-area graphite crystal X-ray spectrometer aboard the OSO-8 satellite is described. The instrument can be used to measure continuum profiles over the energy band from 2 to 8 keV with a resolution of several tens of electron volts and to detect narrow line emission from strong X-ray sources with a limiting sensitivity (3 sigmas) of the order of 10-eV, equivalent width for a three-day observing period.

Kestenbaum, H. L.↗

NASA NTRS1977

Nuclear Science Symposium, 23rd, Scintillation and Semiconductor Counter Symposium, 15th, and Nuclear Power Systems Symposium, 8th, New Orleans, La., October 20-22, 1976, Proceedings

The volume includes papers on semiconductor radiation detectors of various types, components of radiation detection and dosimetric systems, digital and microprocessor equipment in nuclear industry and science, and a wide variety of applications of nuclear radiation detectors. Semiconductor detectors of X-rays, gamma radiation, heavy ions, neutrons, and other nuclear particles, plastic scintillator arrays, drift chambers, spark wire chambers, and radiation dosimeter systems are reported on. Digital and analog conversion systems, digital data and control systems, microprocessors, and their uses in scientific research and nuclear power plants are discussed. Large-area imaging and biomedical nucleonic instrumentation, nuclear power plant safeguards, reactor instrumentation, nuclear power plant instrumentation, space instrumentation, and environmental instrumentation are dealt with. Individual items are announced in this issue.

Wagner, L. J.↗

NASA NTRS1977

Search for thermal X-ray line emission from the Crab Nebula

Observations of the Crab Nebula from 1.85 to 8 keV obtained with the large-area graphite crystal spectrometer on OSO-8 show a smooth featureless continuum with an absence of X-ray emission lines from highly ionized Si and S. Upper limits on the line emission are used to derive an upper limit to the emission measure for a thermal source associated with the Crab Nebula. Existing evidence for an extended thermal source is discussed, and it is shown that the evidence is not contradicted by the upper limits set with the spectrometer data.

Kestenbaum, H. L.↗

NASA NTRS1977

Large area Czochralski silicon

The overall cost effectiveness of the Czochralski process for producing large-area silicon was determined. The feasibility of growing several 12 cm diameter crystals sequentially at 12 cm/h during a furnace run and the subsequent slicing of the ingot using a multiblade slurry saw were investigated. The goal of the wafering process was a slice thickness of 0.25 mm with minimal kerf. A slice + kerf of 0.56 mm was achieved on 12 cm crystal using both 400 grit B4C and SiC abrasive slurries. Crystal growth experiments were performed at 12 cm diameter in a commercially available puller with both 10 and 12 kg melts. Several modifications to the puller hoz zone were required to achieve stable crystal growth over the entire crystal length and to prevent crystallinity loss a few centimeters down the crystal. The maximum practical growth rate for 12 cm crystal in this puller design was 10 cm/h, with 12 to 14 cm/h being the absolute maximum range at which melt freeze occurred.

Rea, S. N.↗

NASA NTRS1978

Effect of pixel dimensions on SAR picture quality

In an SAR mapping system, the product of looks per pixel and number of pixels in the scene is kept constant. Assuming that the returns from all resolution cells obey Rayleigh statistics, the expression for pixel SNR incorporating both speckle and additive white Gaussian noise was derived. It is shown that it is possible to use fine resolution and leave the large-area estimate slightly but not much worse than if a larger pixel size had been initially decided upon.

Pierce, J. R.↗

NASA NTRS1978

Nova Ophiuchi 1977 - An X-ray nova

This letter reports the observation by the HEAO 1 satellite experiments of the X-ray nova in Ophiuchus discovered by Kaluzienski and Holt (1977), which is designated H1705-25. The SAO/MIT scanning modulation collimator has been used in conjunction with the NRL large-area sky survey to give two possible positions for the X-ray nova, each having errors of 0.3 by 1.8 arcmin. The discovery of a 16.5-magnitude optical nova (Nova Ophiuchi 1977) in one of the error boxes is reported, and the X-ray source is identified with the optical nova. The object is classified as being of the A0620-00 and A1524-61 type; i.e., a low-mass binary system.

Griffiths, R. E.↗

NASA NTRS1977

The Maximum Likelihood Estimation of Signature Transformation /MLEST/ algorithm

The Maximum Likelihood Estimation of Signature Transformation (MLEST) algorithm is used to obtain maximum likelihood estimates (MLE) of affine transformation. The algorithm has been evaluated for three sets of data: simulated (training and recognition segment pairs), consecutive-day (data gathered from Landsat images), and geographical-extension (large-area crop inventory experiment) data sets. For each set, MLEST signature extension runs were made to determine MLE values and the affine-transformed training segment signatures were used to classify the recognition segments. The classification results were used to estimate wheat proportions at 0 and 1% threshold values.

Thadani, S. G.↗

NASA NTRS1977

A focusing gas scintillation proportional counter

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 window area of 60 sq cm and a spectral resolution of 10% fwhm or better at 5.9 keV can be obtained.

Anderson, D. F.↗

NASA NTRS1978

New limits on gamma-ray bursts

Two balloon flights of large-area scintillation crystal detector arrays indicate that the rate of weak gamma-ray bursts is significantly below that expected from a uniform distribution of burst sources. This result, combined with the data from stronger bursts, gives strong evidence for a galactic confinement of burst sources. Reasonable models of confinement limit the intrinsic radiated energy per burst to the order of 10 to the (39th to 41st power) ergs.

Fishman, G. J.↗

NASA NTRS1978

Low-cost Solar Array (LSA) project

Progress made by the Low-Cost Silicon Solar Array Project during the period January through March 1978 is reported. It includes task reports on silicon material processing, large-area silicon sheet development, encapsulation materials testing and development, project engineering and operations, and manufacturing techniques, plus the steps taken to integrate these efforts.

Source record↗

NASA NTRS1978

LSA: Low-cost Solar Array project

Topics discussed include silicon material processing; large-area silicon sheet development; encapsulation materials testing and development; project engineering and operations activities, and manufacturing techniques. The steps taken to integrate these efforts, are described.

Source record↗

NASA NTRS1978

A new measurement of the cosmic ray electron spectrum from 10 GeV to 300 GeV

The spectrum of cosmic-ray electrons has been measured with an instrument that combines a transition-radiation detector with a shower detector. The transition-radiation detector provides unique identification of individual electrons and good discrimination against protons. At the same time, it allows the construction of a large-area instrument (0.48 sq m ? ster) and consequently makes possible a measurement of improved statistical accuracy. The instrument has been calibrated with electron beams of 5-300 GeV at Fermilab, thus eliminating energy-dependent biases. A first balloon flight yielded 30 hours of data at an altitude of 5 g/sq cm. The design of the instrument is described, along with the accelerator calibrations and the analysis of the balloon flight data. The spectrum of electrons is found to be significantly steeper than that of protons over the whole energy range.

Hartmann, G.↗

NASA NTRS1978

Development of a process for high capacity-arc heater production of silicon

The realization of low cost, electric power from large-area silicon, photovoltaic arrays will depend on the development of new methods for large capacity production of solar grade (SG) silicon with a cost of less than $10 per kilogram by 1986 (established Department of Energy goal). The objective of the program is to develop a method to produce SG silicon in large quantities based on the high temperature-sodium reduction of silicon tetrachloride (SiCl4) to yield molten silicon and the coproduct salt vapor (NaCl). Commercial ac electric arc heaters will be utilized to provide a hyper-heated mixture of argon and hydrogen which will furnish the required process energy. The reactor is designed for a nominal silicon flow rate of 45 kg/hr. Analyses and designs have been conducted to evaluate the process and complete the initial design of the experimental verification unit.

Reed, W. H.↗