Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “scintillation”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

An imaging gas scintillation proportional counter for the detection of subkiloelectron-volt X-rays

A large area imaging gas scintillation proportional counter (IGSPC) was constructed for use in X-ray astronomy. The IGSPC consists of a gas scintillation proportional counted (GSPC) with a micron polyprotylene window coupled to a multiwire proportional counter (MWPC) via a calcium fluoride window. Over a sensitive area of 21 cu cm the instrument has a measured energy resolution of 17.5% (FWHM) and 1.9 mm (FWHM) spatial resolution at 1.5 keV.

Hailey, C. J.↗
NASA NTRS1981

Solar wind motion within 30 R solar masses - Spacecraft radio scintillation observations

New remote-sensing observations are reported of the solar wind motion within about 30 earth radii. Use is made of the interplanetary scintillation (IPS) spaced receiver technique with the radio source being a spacecraft signal (rather than a natural radio source as in previous spaced receiver studies). The spacecraft used are Helios A and B and the Viking orbiters. The purposes of the study are (1) to augment the scarce estimates of solar wind bulk flow speed near the sun and in the ecliptic with measurements made using spacecraft signals, and (2) to estimate random velocity components and identify the region where the random velocity is a significant fraction of the mean velocity. In addition, the radial evolution of speed and random velocity is compared with that of the plasma density fluctuation spectrum. Also reported are the first accurately normalized IPS scintillation index measurements using a monochromatic point source.

Armstrong, J. W.↗
NASA NTRS1981

The role of in-situ measurements in scintillation modelling

It is shown that the conflicting equatorial scintillation observations obtained from greatly separated ground stations can be organized in the framework of a longitudinal variation of irregularity occurrence, given satellite-borne, in situ measurements of irregularity amplitude of the global F-region irregularity morphology's general features. High-inclination satellite data are used to delineate the morphological features of the polar cap by means of such a method. The lack of diurnal and magnetic control of the irregularity morphology within the low solar flux, northern winter polar cap distinguishes this region from the auroral oval regime. A polar-orbiting communication system sensitive to phase perturbations may observe large differences in the phase-to-amplitude scintillation ratio, as it traverses the auroral oval and proceeds into the polar cap, with its sun-aligned arc system.

Basu, S.↗
NASA NTRS1981

Position measurements for heavy ion beams using a sodium iodide scintillator

A 50 cm diameter, 1.7 cm thick disc of NaI scintillator has been mounted to permit edge viewing by four photomultipliers. Energetic heavy ions passing through the scintillator at different positions cause a variation in the division of light among the photomultipliers. A performance close to the expected limit for 670 MeV/n neon has been achieved. Calculations of expected response using an optical model agree well with the measurements.

Buffington, A.↗
NASA NTRS1983

Gamma ray detection with long NaI/Tl/ scintillator bars

Test measurements with a prototype NaI(Tl) scintillator for energy, position, and timing measurements in gamma ray astronomy are reported. The scintillator bar is 100 x 5 x 5 cu cm in size, and allows detection of the arrival times and pulse heights of signals from two photomultiplier tubes, one at each end of the bar. Data is gathered on the energy loss, linear position, and time-of-flight of gamma ray interactions within the bar over an energy range of 0.5-20 MeV. A mean attenuation coefficient of 0.015/cm has been determined, as have a FWHM resolution of 5 cm, 9.4%, and 10 nsec at an energy of 0.662 MeV. At 1.25 MeV the timing resolution was 6 nsec, and at 6.13 MeV the spatial resolution was 2.2 cm. The instrument is a prototype of a Compton scatter telescope being constructed for two balloon flights, one each in the Northern and Southern Hemispheres, in 1984.

Zych, A. D.↗
NASA NTRS1985

Fast scintillation counter system and performance

An experimental study of the fast scintillation counter (FS) system to observe a shower disk structure at Mt. Norikura is described, especially the system performance and a pulse wave-form by a single charge particles. The photomultiplier tube (PT) pulse appears at the leading edge of the main pulse. To remove this PT-pulse from the main pulse, the frame of the scintillator vessel was changed. The fast triggering system was made to decrease the dead time which came from the use of the function of the self triggering of the storage oscilloscope (OSC). To provide a new field on the multi-parameter study of the cosmic ray showers, the system response of the FS system also improved as a result of many considerations.

Sasaki, H.↗
NASA NTRS1985

Microprocessor-based single particle calibration of scintillation counter

A microprocessor-base set-up is fabricated and tested for the single particle calibration of the plastic scintillator. The single particle response of the scintillator is digitized by an A/D converter, and a 8085 A based microprocessor stores the pulse heights. The digitized information is printed. Facilities for CRT display and cassette storing and recalling are also made available.

Mazumdar, G. K. D.↗
NASA NTRS1985

On method of muon spectrum measurements by the scintillation detectors of a large thickness T4t sub o

Various methods for the study of muon spectrum are presented. The direct ones include the muon energy measurements by magnetic spectrometers. The indirect ones deal with the reconstruction of the muon spectrum from the spectrum of secondary particles obtained by burst or calorimeter technique. The burst technique is based on the measurement of the number of cascade particles, mainly in the cascade maximum, by the detectors of small thickness T sub 0. The calorimeter method consist in determination of the cascade energy with help of the cascade curve shape. The multilayer detectors are used for this purpose. They are usually comprised of proportional counters, X-ray emulsion chambers or scintillation counters with the target material placed between them. The scintillation detectors of a large thickness measures the total cascade energy directly and the detector works as a true calorimeter. When the total energy is detected, the cascade spectrum differs from the muon one.

Ryazhskaya, O. G.↗
NASA NTRS1985

The homestake surface-underground scintillations: Description

Two new detectors are currently under construction at the Homestake Gold Mine a 140-ton Large Area Scintillation Detector (LASD) with an upper surface area of 130 square meters, a geometry factor (for an isotropic flux) of 1200 square meters, sr, and a depth of 4200 m.w.e.; and a surface air shower array consisting of 100 scintillator elements, each 3 square meters, spanning an area of approximately square kilometers. Underground, half of the LASD is currently running and collecting muon data; on the surface, the first section of the air shower array will begin operation in the spring of 1985. The detectors and their capabilities are described.

Cherry, M. L.↗
NASA NTRS1984

Interpretation and modeling of quasiperiodic diffraction patterns observed in equatorial VHF scintillation due to plasma bubbles

Quasiperiodic diffraction patterns have been observed in VHF scintillation recorded at Ascension Island in 1981. The patterns occur most often at the beginning or end of a scintillation patch and are shown to be consistent with those expected from irregularities having east-west scale sizes of a few hundred meters that are associated with the walls (edges) of equatorial plasma bubbles. By adjusting the geophysical parameters in a computer simulation of the amplitude fluctuations expected simultaneously at VHF, L-Band and C-Band, we model a specific event in detail. The model contains information on the size and strength of the structures that cause the regular fading patterns. In addition, multi-frequency diffraction patterns are computed for a 'phase screen' model based on high resolution measurements of a structured plasma bubble wall made using the AE-E satellite. The results are qualitatively very similar to the observations. Finally, implications of the model results for the extraction of information about the vertical structure of the irregularities are discussed.

Franke, S. J.↗
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

Photofraction of a 5 cm x 2 cm BGO scintillator

The photofraction of a 5.1 cm x 2.0 cm bismuth germanate (BGO) scintillator was measured over a gamma-ray energy range of 0.2 to 6.1 MeV. Several methods, used to minimize the effect of room scattering on the measurement, are discussed. These include a gamma-gamma coincidence technique, a beta-gamma coincidence technique, and the use of sources calibrated with a standard 7.6 cm x 7.6 cm sodium iodide scintillator.

Dunphy, P. P.↗
NASA NTRS1983

Scintillator-fiber charged-particle track-imaging detector

A scintillator-fiber charged-particle track-imaging detector has been developed using a bundle of square cross-section plastic scintillator fiber optics, proximity focused onto an image intensified Charge Injection Device (CID) camera. Detector to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei have been exposed and images of their tracks are obtained. This paper presents details of the detector technique, properties of the tracks obtained, and range measurements of 15 MeV protons stopping in the fiber bundle.

Binns, W. R.↗
NASA NTRS1984

A large area imaging gas scintillation proportional counter for use in X-ray astronomy

A large area (200 sq cm), broad bandwidth (0.1-70 keV), imaging gas scintillation proportional counter (IGSPC) has been constructed for use in X-ray astronomy. The IGSPC consists of a high pressure xenon gas scintillation proportional counter (GSPC) coupled to a multi-wire 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 detector has a measured energy resolution of 8.0 percent (FWHM) and 4.3 percent (FWHM) at 5.9 keV and 22.1 keV, respectively. The predicted spatial resolution of the detector is less than 1 mm (FWHM) between 3-22 keV and 37-60 keV. A method to determine the three-dimensional location of detected X-rays is described. In addition, a combination of discrimination schemes designed to reduce the non-X-ray background in the IGSPC by more than two orders of magnitude is discussed.

Ku, W. H.-M.↗
NASA NTRS1986

Studies of air showers produced by primaries 10(16) eV using a combined scintillation and water-Cerenkov array

An array of 8 x 1.0 sq m plastic scintillation counters and 13 water-Cerenkov detectors (1 to 13.5 sq m) were operated at the center of the Haverah Park array to study some features of air showers produced by 10(16) eV primaries. Measurements of the scintillator lateral distribution function, the water-Cerenkov lateral distribution function, and of the distance dependence of the Cerenkov/scintillator ratio are described.

Brooke, G.↗
NASA NTRS1986

Strong scintillations during atmospheric occultations Theoretical intensity spectra

Each of the two Voyager spacecraft launched in 1977 has completed a reconnaissance of the Jovian and Saturnian systems. In connection with occultation experiments, strong scintillations were observed. Further theoretical work is required before these scintillations can be interpreted. The present study is, therefore, concerned with the derivation of a theory for strong scattering during atmospheric occultation experiments, taking into account as fundamental quantity of interest the spatial spectrum (or spectral density) of intensity fluctuations. Attention is given to a theory for intensity spectra, and numerical calculations. The new formula derived for Phi-i accounts for strong scattering of electromagnetic waves during atmospheric occultations.

Hinson, D. P.↗