Search NASA⌕ Search

SEARCH · Search NASA

Results for “gamma-ray detector”

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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1961

A Satellite Borne Cadmium Sulfide Total Corpuscular Energy Detector

The properties of single crystals of cadmium sulfide as radiation detectors are described. It has been found possible to select crystals such that: (a) The ratio of increase of conductivity under irradiation to the rate of absorption of energy in the crystal is substantially independent of particle energy (over the examined ranges of 500 ev to 80 kev for electrons and 5 kev to 180 kev for protons) and of the magnitude of energy flux (over the range from.005 to 10 ergs/cm(sup 2 -sec); and (b) The above ration is substantially the same for protons, electrons, alpha particles, x-rays, and gamma-rays. For a driving voltage of 100 volts, typical crystal yield currents of 10(sup -7) to 10(sup- 6) amperes for each erg/cm(sup 2-sec) of energy absorbed by the crystal. The threshold of such crystal detectors (resulting from dark currents of the order of 10(sup 10 amp) is typically 10(sup -3) ergs/cm(sup 2- sec). For the selected crystals a response-temperature coefficient of -0.25% per degree centigrade is found for the temperature range -50 deg C to + 50 deg C. A description is given of a complete CdS total corpuscular energy detector for the study of geomagnetically trapped radiation by means of a satellite. The detector described has a dynamic range great than 10(sup 4), a solid angle of 10(exp -3) steradian, and a detection threshold of approximately 1 erg/cm(sup 2-sec-sterad). A similar detector employing a small magnet for the selective exclusion of electrons is also described. Noteworthy practical features of these detectors for satellite and space probe experiments are: (a) Use of bare crystals, without covering foils, in order to detect charged particles having energies as low as hundreds of electron volts. (b) Simplicity of electronic auxiliaries. (c) Compactness, lightweight and nechanical ruggedness. (d) Low electrical power requirements; and (e) Conversion of conduction current to the rate of a twostate relaxation oscillator in order to facilitate telemetric transmission of data. A pair of such detectors was flown as part of the s-46 satellite payload on March 23, 1960, but due to vehicular failure an orbit was not achieved and the operation of the CdS detectors was observed for only, six minutes of flight.

Freeman, John W.↗
NASA NTRS1974

International Cosmic Ray Conference, 13th, University of Denver, Denver, Colo., August 17-30, 1973, Proceedings. Volumes 3 & 4

Volumes 3 and 4 contain papers dealing with measurements of muons and neutrinos, ultrahigh-energy interactions, extensive air showers, and details of experimental techniques and instrumentation. Attention is given to the zenith angle and underground depth dependence of cosmic ray muons, muon charge ratios and energy spectra, extraterrestrial sources of neutrinos, strong interaction data from new accelerators, searches for quarks and other new particles, hadron fluxes and propagation in the atmosphere, high-energy gamma-ray measurements, and new models and theories for high-energy strong interactions. Extensive air showers are examined in papers dealing with associated Cerenkov light, radio emission, structure, the hadron content, and primaries. The design, operation, and performance of various detectors are explained. Individual items are announced in this issue.

Source record↗
NASA NTRS1969

New shield for gamma-ray spectrometry

Gamma-ray shield that can be evacuated, refilled with a clean gas, and pressurized for exclusion of airborne radioactive contaminants effectively lowers background noise. Under working conditions, repeated evacuation and filling procedures have not adversely affected the sensitivity and resolution of the crystal detector.

Brar, S. S.↗
NASA NTRS1973

IMP-6 observations of the energy spectra of cosmic gamma-ray bursts

The occurrence of intense, short bursts of 0.1 to 1.2 MeV cosmic gamma rays, recently found using multiple Vela satellites was confirmed with measurements from the IMP-6 satellite. Observations regarding times of occurrence, photon flux, and temporal and spectral characteristics of the bursts are outlined. In particular, since the IMP-6 instrument incorporates a hard X-ray detector with active particle rejection and full-time omnidirectional particle intensity monitoring, the results fully confirm and establish the hard X-ray or gamma-ray nature of the incident flux. Detailed differential energy spectra were obtained with the IMP-6 for six of the eight known events occurring during the March 1971 to September 1972 lifetime of the instrument. All of these are multiple-pulse events, with several seconds separation between distinct pulses of one or two seconds duration. The pulse spectra do not obey single-index power laws in energy, but can be represented by exponentials in photon flux throughout the 100 to 1200 KeV region.

Cline, T. L.↗
NASA NTRS1971

Digital methods of photopeak integration in activation analysis.

A study of the precision attainable by several methods of gamma-ray photopeak integration has been carried out. The 'total peak area' method, the methods proposed by Covell, Sterlinski, and Quittner, and some modifications of these methods have been considered. A modification by Wasson of the total peak area method is considered to be the most advantageous due to its simplicity and the relatively high precision obtainable with this technique. A computer routine for the analysis of spectral data from nondestructive activation analysis experiments employing a Ge(Li) detector-spectrometer system is described.

Baedecker, P. A.↗
NASA NTRS1974

Observations of cosmic gamma-ray bursts with IMP-7: Evidence for a single spectrum

Spectral observation of nine recent cosmic gamma-ray bursts are reported. The average photon number spectra of all nine events are shown to be consistent with a 150-keV exponential from 100 keV to about 400 keV, and a power law of index -2.5 from 400 keV to 1100 keV. The observations also indicate an event rate of 16 in 1972 and 1973, or 8 + or - 2 per year, higher than the 5 + or - 1 per year initially reported. This corresponds to an approximately 40-percent lower effective intensity threshold, attained by using more sensitive detectors in multiple-satellite coincidence.

Cline, T. L.↗
NASA NTRS1975

Observations of cosmic gamma-ray bursts with IMP-7 - Evidence for a single spectrum

Spectral observations of nine recent cosmic gamma-ray bursts are reported. The average photon number spectra of all nine events are each consistent with a 150-keV exponential from 100 keV to about 400 keV, and a power law of index -2.5 from 400 keV to 1100 keV. The observations also indicate an event rate of 16 in 1972 and 1973, or 8 plus or minus 2 per year, higher than the 5 plus or minus 1 per year initially reported. This corresponds to an approximately 40 percent lower effective intensity threshold, attained by using more sensitive detectors in multiple-satellite coincidence.

Cline, T. L.↗
NASA NTRS1975

Interpretation of various radiation backgrounds observed in the gamma-ray spectrometer experiments carried on the Apollo missions and implications for diffuse gamma-ray measurements

Since the report of a preliminary analysis of cosmic gamma-ray measurements made during the Apollo 15 mission, an improved calculation of the spallation activation contribution has been made including the effects of short-lived spallation fragments, which can extend the correction to 15 MeV. In addition, a difference between Apollo 15 and 16 data enables an electron bremsstrahlung contribution to be calculated. A high level of activation observed in a crystal returned on Apollo 17 indicates a background contribution from secondary neutrons. These calculations and observations enable an improved extraction of spurious components and suggest important improvements for future detectors.

Dyer, C. S.↗
NASA NTRS1963

HIGH-ENERGY GAMMA-RAY ASTRONOMY

Brief review of the present status of high-energy gamma-ray astronomy and a report of results from the orbiting solar observatory

EXTRATERRESTRIAL RADIATION↗
NASA NTRS1968

Gamma-ray astronomy.

Space gamma radiation in form of quanta with extremely high energies, discussing satellite- borne detectors, spark chambers, etc

Fichtel, C. E.↗
NASA NTRS1970

Gamma-ray astronomy balloon results

Gamma ray astronomical point sources by balloon flight and satellite observation, discussing detector system and telescope for flux and energy spectrum

Fichtel, C. E.↗
NASA NTRS1973

Gamma-ray observations of the galactic centre.

Review of observation data obtained with a portable gas-Cerenkov gamma-ray telescope flown twice from Parana, Argentina (31.8 deg S), to search for gamma radiation from the galactic center. The angular resolution of this detector is not good enough to resolve the source structure controversy, i.e. whether the gamma radiation is coming from point sources or from a diffuse source along the galactic plane. Comparisons with observation data of other investigators are presented and discussed.

Helmken, H. F.↗
NASA NTRS1973

HEAO gamma-ray astronomy experiments

Two gamma ray experiments designed to measure and map the cosmic gamma ray spectrum in the 0.1 to 10 MeV region are outlined. The sensitivity and capability of the instruments- a high resolution gamma ray spectrometer that uses solid state detectors and a combined UCSD-MIT scintillation system are also given. These experiment were designed for the HEAO program.

Metzger, A. E.↗
NASA NTRS1974

Observation of a cosmic gamma-ray burst on Apollo 16. II - X-ray time profile and source location

A burst of X-rays was detected during the trans-earth coast phase of Apollo 16 on Apr. 27, 1972 at 10:68 UT, simultaneously with the observation of a transient event by a gamma-ray spectrometer aboard the same spacecraft. The two instruments provide a broad energy range of more than three orders of magnitude for describing the spectral distribution of this event. The conclusion that the incident flux was X-rays and not charged particles is based on the fact that the particle flux detectors in the Apollo gamma ray spectrometer and on the Vela 6A, which also observed the event, did not respond. The time variation of the total count rate in the X-ray range before and after corrections for detector geometry and the analysis for source direction is presented.

Trombka, J. I.↗