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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

An imaging telescope for high energy gamma-ray astronomy

Recent tests of a gamma-ray imaging telescope, which incorporated a coded aperture mask and multiwire proportional counter system produced good images of a tritium target source which was used to generate the 20 MeV protons at a proton Van de Graaff accelerator. This paper indicates what performance might be expected if a large area drift chamber were used in conjunction with a coded aperture mask. The prospects for achieving significant scientific results if such a system were flown on a variety of space vehicles are discussed.

Frye, G.↗
NASA NTRS1985

Wire-Identification Instrument

Instrument automatically tests each wire in multiwire cable and identifies specified wire to be segregated or labeled and locates wire connected to specified connector pin. Instrument made with readily available CMOS integrated circuits. More efficient and reliable than conventional continuity testers and less expensive than computer controlled units.

Lonborg, J. O.↗
NASA NTRS1983

An imaging gas scintillation proportional counter for use in X-ray astronomy

An imaging gas scintillation proportional counter (GSPC) has been constructed for use in X-ray astronomy. The IGSPC consists of a gas scintillation proportional counter (GSPC) with a 1 micron polypropylene window coupled to a multiwire proportional counter (MWPC) via a calcium fluoride window. The MWPC, filled with a mixture of argon, methane, and tetrakis (dimethylamino) ethylene, detects the UV photons emitted by the xenon gas in the GSPC. The measured energy resolution is 17.0 percent (fwhm) and 8.0 percent (fwhm) at 1.5 keV and 5.9 keV, respectively. The measured position resolution is 1.9 mm (fwhm) and 0.9 mm (fwhm) at 1.5 and 5.9 keV, respectively. Possible astrophysical observations which can be performed with an IGSPC at the focal plane of a grazing incidence telescope are also discussed.

Hailey, C. J.↗
NASA NTRS1985

Composition of cosmic-ray nuclei from boron to nickel for 1200 to 2400 MeV per nucleon

Balloon-borne measurements of cosmic-ray nuclear abundances for Z = 5-28 and energies 1.2-1.4 GeV/nucleon, obtained using the scintillation/Cerenkov-counter telescope and multiwire proportional counter described by Dwyer et al. (1984) on four flights from Texas and Oklahoma during 1973-1975, are reported. The data are presented in tables and graphs and compared with published observations. Charge separation (sigma = 0.2 units for Fe) and exposure factor (38 sq m sr h) are attained, and the findings are found to be in good agreement with the predictions of a simple leaky-box model of the Galaxy and a pure exponential path-length distribution, although a nested-leaky-box model with some truncation is possible. The delay between e-process nucleosynthesis and cosmic-ray acceleration is estimated on the basis of the Co abundance at greater than 100 d and probably greater than 100,000 yr.

Dwyer, R.↗
NASA NTRS1986

An imaging proportional counter for a 0.1 to 10 keV X-ray telescope

A xenon multiwire position-sensitive proportional counter (PSPC) with a high degree of long-term stability has been constructed and tested in detail. It is suitable for a 0.1 to 10 keV X-ray telescope such as AXAF, which it would share with detectors having better spatial and spectral resolution. Compared to other detectors, the larger format, higher quantum efficiency, and lower background of the PSPC makes it generally the most useful instrument for observations of diffuse cosmic X-ray sources and associations of sources more extended than a few tenths of a degree in diameter. Given the good spatial linearity, the systematic uncertainty for source locations is finer than an arcsecond. The spatial resolution varies as 0.3 mm/exp 0.5 (keV) over the range 0.2-4 keV, in accordance with theoretical limits determined by the size and the number of electrons in the primary charge cloud.

Gorenstein, P.↗
NASA NTRS1986

Fast transients - A search in X-rays for short flares, bursts, and related phenomena

The HEAO 1 A-2 database on fast high energy X-ray transients was examined for any discernible regularities. The data were taken over the interval 1977-79 with six collimated multiwire, multilayer, proportional counters that had a sensitivity sufficient for detecting events lasting 1-5 sec at energies as low as 8-120 keV. The entire sky was surveyed completely three times in the observational period. Best-fit position, error box corners, mean transient flux and quiescent flux data are provided for all six of the type 3 events that were found. All the sources were within the Galaxy. The duration of the events ranged from 60-2000 sec. The limited number of events observed leads to estimates of 10,000-200,000 events per year. It is suggested that all the events originate from hard flares occurring at a rate of 20,000/yr on dMe/dKe stars.

Connors, A.↗
NASA NTRS1987

Cosmic ray detectors

Work on the MSFC emulsion laboratory microscopes in which mechanical modifications previously made were verified is reviewed, as is a design study of a large area hybrid electronic/emulsion chamber balloon flight detector system. This design is built upon the experience obtained with the highly successful MSFC/UAH hybrid instrument flown by the JACEE consortium. The design included overall system design and specification, design and fabrication of a prototype large light diffusion for Cerenkov charge detector or scintillator, design of a multiwire proportional counter array and design of the gondola or flight support system.

Gregory, John C.↗
NASA NTRS1986

Development of a multistep detector for X-ray astronomy

The addition of a preamplification region is shown to dramatically improve the performance of a standard multiwire proportional counter (MWPC). This improvement is a direct consequence of effecting a large degree of preamplification in a perfectly uniform electric field and then transferring a well defined portion of this charge to a MWPC running at a modest gain. In this way, very large overall gas gains can be achieved without compromising energy resolution. The resulting device is known as a multistep detector.

Ramsey, B. D.↗
NASA NTRS1986

On the energy resolution obtained with a multistep proportional counter

Results of laboratory experiments with a standard multiwire imaging proportional counter (MWPC), modified to include a parallel grid preamplification stage are presented. Both argon and xenon were used as the primary absorbing gas in conjunction with a number of quench gases. It is found that extremely good energy resolution is obtained from the preamplification stage, almost independent of the ionization potential of the quench gas and over a broad range of gains. Furthermore, regardless of absorbing gas or quench agent, there was no difficulty in transferring a portion of this preamplified charge to the MWPC section for multistep mode operation. Finally, even for overall system gains greater than 10,000, the energy resolution from the second stage is found to be significantly improved, as long as the preamplification stage is operating. These results should have wide application and are of special interest for X-ray astronomy.

Ramsey, B. D.↗
NASA NTRS1987

The performance of a multistep proportional counter for use in X-ray astronomy

The addition of a parallel field preamplification region has been shown to dramatically improve the performance of a standard multiwire proportional counter, permitting high overall gas gains to be achieved, a prerequisite for good spatial resolution, without in any way compromising energy resolution. The resulting device, known as a multistep detector, has been tested over a wide range of operating conditions and fill gas mixtures. Results are presented here detailing the performance available with argon and xenon as the principal gases, these being of particular relevance to X-ray astronomy.

Ramsey, B. D.↗
NASA NTRS1987

Cosmic-ray elemental abundances from 1 to 10 GeV per amu for boron through nickel

The relative abundances of cosmic-ray nuclei in the charge range boron through nickel over the energy range 1-10 GeV per amu were measured with a balloon-borne detector. The instrument consists of a scintillation and Cerenkov counter telescope with a multiwire proportional chamber hodoscope and has been flown in four high-altitude balloon flights. Good charge resolution (sigma = 0.2 charge units at iron) and high statistical accuracy have been achieved. These data are used to derive the energy dependence of the leakage path length using the leaky box model of propagation and confinement in the galaxy. This energy dependence is found to be best fit by lambda = E(tot) exp -n, where n = 0.49 + or - 0.06 over 1-10 GeV per amu. Relative abundances at the source are consistent with an energy-independent composition.

Dwyer, Robert↗
NASA NTRS1988

A broad band X-ray imaging spectrophotometer for astrophysical studies

A broadband X-ray imaging spectrophotometer (BBXRIS) has been built for astrophysical studies. The BBXRIS is based on a large-imaging gas scintillation proportional counter (LIGSPC), a combination of a gas scintillation proportional counter and a multiwire proportional counter, which achieves 8 percent (FWHM) energy resolution and 1.5-mm (FWHM) spatial resolution at 5.9 keV. The LIGSPC can be integrated with a grazing incidence mirror and a coded aperture mask to provide imaging over a broad range of X-ray energies. The results of tests involving the LIGSPC and a coded aperture mask are presented, and possible applications of the BBXRIS are discussed.

Lum, Kenneth S. K.↗
NASA NTRS1988

Legislated emergency locating transmitters and emergency position indicating radio beacons

An emergency locating transmitting (ELT) system comprising a legislated ELT modified with an interface unit and connected by a multiwire cable to a remote control monitor (RCM), typically located at the pilot position. The RCM can remotely (1) test the ELT by disabling the legislated swept tone and allowing transmission of a single tone, (2) turn the ELT "on" for the legislated ELT transmission, and (3) reset the ELT to an "armed" condition. The RCM also provides visual and audio indications for transmitter operating condition as well as ELT battery condition. Removing the RCM or shorting or opening the interface input connections will not affect traditional ELT operation.

William R Wade↗
NASA NTRS1988

Upper limits to the high-energy gamma-ray and hard X-ray flux from SN 1987A on day 55

A balloon-borne experiment was carried out on April 19, 1987 from Alice Springs, Australia to detect high-energy gamma-rays and hard X-rays from the supernova SN 1987A in the Large Magellanic Cloud. An optical spark chamber for measuring the high-energy gamma-rays and a multiwire proportional counter for measuring the hard X-rays shared a common balloon platform. No positive emission was observed by either detector. The gamma-ray upper limit obtained indicates that either the expanding supernova shell was opaque to gamma-rays at the time of the flight, or that the supernova cosmic ray luminosity was less than about 10 to the 40th erg/s. The X-ray upper limit obtained confirms the opacity of the shell to Comptonized hard X-rays.

Sood, R. K.↗
NASA NTRS1989

The MSFC large-area imaging multistep proportional counter

A large-area multistep imaging proportional counter that is being currently developed at the Marshall Space Flight Center is described. The device, known as a multistep fluorescence gated detector, consists of a multiwire proportional counter (MWPC) with a preamplification region. The MWCP features superior spatial resolution with a very high degree of background rejection. It is ideally suited for use in X-ray astronomy in 20-100 keV energy range. The paper includes the MWPC schematic and a list of instrument specifications.

Ramsey, B. D.↗
NASA NTRS1994

Method of locating ground faults

The present invention discloses a method of detecting and locating current imbalances such as ground faults in multiwire systems using the Faraday effect. As an example, for 2-wire or 3-wire (1 ground wire) electrical systems, light is transmitted along an optical path which is exposed to magnetic fields produced by currents flowing in the hot and neutral wires. The rotations produced by these two magnetic fields cancel each other, therefore light on the optical path does not read the effect of either. However, when a ground fault occurs, the optical path is exposed to a net Faraday effect rotation due to the current imbalance thereby exposing the ground fault.

Patterson, Richard L.↗
NASA NTRS1997

RXTE observations of AGN

The Rossi X-ray Timing Explorer (RXTE) observed three active galaxies during its in-orbit verification phase: NGC 4151; NGC 4945, and MCG 8-11-11. All three were detected from 2 keV to more than 100 keV by a combination of the proportional counter array (PCA) and the high energy X-ray timing experiment (HEXTE). The PCA contains five, xenon/methane, multilayer, multiwire, gas proportional counters covering the 2 to 60 keV range, while HEXTE is an array of eight NaI/CsI phoswich scintillation counters covering the 15 to 250 keV range. The three active galaxies represent the classes of Seyfert 1, Seyfert 2 and intermediate Seyfert galaxies. The results of the fitting of various models containing partial covering fractions, Compton reflection components and high energy spectral breaks are discussed.

Rothschild, R. E.↗
NASA NTRS1997

Neutron Induced Backgrounds In the MIXE X-Ray Detector at Balloon Altitudes

The MIXE detector developed at NASA/MSFC is designed for x-ray astronomy and consists of a multiwire proportional counter sensitive to photons less than 150 keV. The detector has been flown on several balloon flights with higher than expected background levels observed. Previous predictions of the detector background due to atmospheric gamma-ray and cosmic diffuse sources were much less (factor of 3) than flight background measurements. The work reported here was undertaken to determine if the additional contribution from gamma-rays generated by albedo and cosmic-ray induced neutrons in the detector and payload assembly could account for the background levels observed. Monte Carlo nuclear interaction and radiation transport simulations were made for the ambient cosmic-ray environment corresponding to a previous MEE balloon flight at 3 g/cm(exp 2) residual atmosphere and 42 N geomagnetic latitude. The omnidirectional albedo neutron spectrum and the GCR proton spectrum which were used as input to the calculations are shown. For the albedo angular distribution, the predicted up/down flux ratio of 2.5 was used together with the angular dependence measured by Preszler, et al.

Armstrong, T. W.↗