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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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NASA NTRS1975

A balloon-borne ionization spectrometer with very large aperture for the detection of high energy cosmic rays

A balloon experiment which was used to determine the chemical composition of very high-energy cosmic rays up to and beyond 100 GeV/nucleon is described. The detector had a geometric factor of 1 sq m sr and a total weight on the balloon of 2100 kg. The apparatus consisted of an ionization spectrometer, spark chambers, and plastic scintillation and Cherenkov counters. It was calibrated at CERN up to 24 GeV/c protons and at DESY up to 7 GeV/c electrons. In October 1972 it was flown successfully on a stratospheric balloon.

Atallah, K.↗
NASA NTRS1975

High-energy gamma-ray astronomy

The subject of gamma-ray astronomy is discussed with emphasis on celestial gamma rays with energies in excess of 10 MeV. Early observations of such gamma rays are reviewed, a gamma-ray spark-chamber telescope is described together with a gas Cerenkov-counter telescope, and the gamma-ray sky is delineated. It is shown that the diffuse high-energy gamma radiation from the galactic plane probably results primarily from cosmic-ray interactions with interstellar matter. Mechanisms for gamma-ray production are identified, and it is noted that the general galactic radiation may prove to be of great value in studies of galactic structure. Possible sources are considered for the diffuse celestial radiation, and discrete sources are described, including the Crab pulsar, the Vela remnant, the Cygnus region, and Gould's Belt. Future developments in gamma-ray astronomy are considered.

Fichtel, C.↗
NASA NTRS1975

The isotopic composition of cosmic rays with 5 is less than or equal to z which is less than or equal to 26

Results obtained from a high altitude balloon flight from Thompson, Canada in August, 1973 are reported. The instrument consisted of a spark chamber, a Lucite Gerenkov counter and thirteen layers of scintillators. For heavy particles the Cerenkov-range method of analysis was used to determine the mass of particles energetic enough to produce a Cerenkov signal and then stop in the layered scintillators. The data appear to be consistent with current cosmic-ray propagation models. Using a simple exponential path length propagation model this data is extrapolated to the cosmic-ray source and some implications of the data are discussed as to the nature of the source.

Fisher, A. J.↗
NASA NTRS1976

On the Age of Cosmic Rays as Derived from the Abundance of Be-10

The isotopic composition of cosmic ray Be, B, C, and N was studied using a new range versus total light technique. Special emphasis was placed on the Be isotopes and in particular, on the radioactive isotope Be-10 due to its mean lifetime against decay. The experiment consisted of a thin trigger scintillator, an acrylic plastic Cerenkov detector and a spark chamber, followed by a totally active stack of 14 scintillation detectors. This stack of scintillators made possible the measurement of range, and also permitted the removal of interacting events by continuously monitoring their identities along their trajectories. The experiment was carried by balloon to atmospheric depths ranging from 3.5 to 5.0 g sq cm residual atmosphere for a total exposure time of 23 hr. Results indicate the survival of ( 55 + or -21) % of the Be-10 in the arriving cosmic rays; the data were interpreted using the leaky box model of cosmic ray propagation.

Hagen, F. A.↗
NASA NTRS1975

Cosmic-ray composition measurements with high-energy ionization spectrometers

Element abundances of cosmic rays for elements Li through Si with energy above 0.8 GeV/amu were measured on a balloon-borne instrument containing a total absorption ionization spectrometer. Statistical techniques were used to analyze the five measurements of each particle to determine its charge and energy. The technique allows a determination of systematic errors to be made. Corrections for Landau fluctuations, spark-chamber inefficiency, and background particles were included. Comparison with other published results is made. There are differences in the shapes of the differential spectra determined from measurements using different techniques, and our intensities still lie somewhat below those of other workers.

Arens, J. F.↗
NASA NTRS1975

A Cerenkov-Range analysis of the isotopic composition of cosmic rays with Z from 6 to 26

High-altitude balloon data on the isotopic composition of heavy cosmic rays are reported. The experiment used a Cerenkov detector, arrays of scintillators, and a digitized wire spark chamber. Peaks assigned to the mono-isotopic elements F and Na indicate that an absolute mass scale can be derived from the data. Even-Z elements in the Z range from 12 through 16 are represented mainly by alpha-particle nuclei. Neutron-rich components dominate in the case of neon present. Mass histograms are plotted for C, O, N, Ne, Mg, and Fe.

Fisher, A. J.↗
NASA NTRS1975

Cosmic ray positron and negatron spectra between 20 and 800 MeV measured in 1974

A balloon-borne spark-chamber magnetic spectrometer has been used to measure separate spectra of positrons and negatrons in two flights during the summer of 1974. The flights reached atmospheric depths of 1.9 and 1.5 g/sq cm after slow ascents which enhance the statistical accuracy of the atmospheric secondary subtraction. The total electron flux is about sq m/s/sr/MeV between 70 and 800 MeV, and increases toward lower energies. The positron spectrum decreases sharply toward lower energies from a value of about 0.08 sq m/s/sr/MeV at 650 MeV, and only upper limits are obtained for positrons below 200 MeV.

Hartman, R. C.↗
NASA NTRS1975

Magnetic mass spectrometer search at 2750 m. for hypothetical massive particles

A search was conducted for hypothetical singly charged massive particles which might be produced in collisions of very highly energetic cosmic ray particles with nuclei in the upper atmosphere. If such particles have sufficiently long lifetime and small cross section for interaction, they could survive to mountain altitude. A cosmic ray spectrometer consisting of superconducting magnet, wire spark chambers and time-of-flight scintillation counters was used to search for these particles at mountain altitude (2750 m). For any choice of hypothetical mass in the 5 to 10 GeV/c-squared range the upper limit to the vertical intensity of the particle was observed to be less than or roughly equal to 10 to the -6th/sq. cm/s/(GeV/c).

Barber, H. B.↗
NASA NTRS1975

Cosmic ray mass and momentum spectra at mountain altitude

A cosmic ray mass spectrometer using a superconducting magnet, digitized wire spark chambers, and a scintillation counter time of flight system, has been operated at an altitude of 2750 meters. The apparatus is most sensitive to charged particles with momentum to mass ratios between 0.2 and 2.0. Results for the momentum spectra of protons and deuterons are presented, as well as upper limits for H-3 and He-3. The reaction nucleon + nucleon yields deuteron + pion accounts for part of the observed deuteron spectrum in the 0.9 to 3 GeV/c region.-

Barber, H. B.↗
NASA NTRS1975

Detection of the isotopes of heavy cosmic ray nuclei

A counter telescope designed to detect and resolve the isotopic composition of cosmic ray nuclei heavier than neon is being prepared. The telescope consists of a rather conventional charge measuring array using two scintillator elements and two solid Cerenkov radiators of differing refractive index. The mass measurement is obtained by combining the velocity information from one or both of the Cerenkov radiators operating near their threshold with residual range measured in a block of nuclear emulsion. Path length corrections and particle location in the emulsions is provided by a spark chamber fired in coincidence with potentially suitable particles. The telescope has a geometry factor of 530 sq cm sr roughly. It should be able to resolve the isotopes of iron over the energy range of 300 to 720 Mev/n and those of neon over 300 to 400 MeV/n. The expected response and characteristics of the telescope are described in detail and the sensitivity to rare isotopes discussed.

Gilman, C. M.↗
NASA NTRS1976

Cosmic-ray positron and negatron spectra between 20 and 800 MeV measured in 1974

The flux density of cosmic-ray positrons and electrons was measured by a balloon-borne spark chamber magnetic spectrometer in two flights in an attempt to study the solar modulation of galactic cosmic rays. The total electron flux was found to be about 0.03/cu m/s/sr/MeV between 70 and 800 MeV and to increase toward lower energies, while the positron flux decreased sharply toward lower energies from about 0.008/cu m/s/sr/MeV at 650 MeV and only upper limits were obtained for positrons below 200 MeV. At energies above 180 MeV, the spherically symmetrical Fokker-Planck equation with a diffusion coefficient proportional to the particle rigidity provided a reasonable fit to both positron and total electron data, while at energies below 180 MeV, the data were consistent with a continuation of the same diffusion coefficient and local source of electrons, or a change in the diffusion coefficient to a constant value.

Hartman, R. C.↗
NASA NTRS1977

Intensity of primary cosmic-ray electrons of energy exceeding 8 GeV

Results are reported for measurement of the intensity and energy spectrum of primary cosmic-ray electrons with a spark-chamber-counter-emulsion detector flown at a mean altitude of 3 g/sq cm residual atmosphere. A least-squares fit to the flight data yields an electron spectrum from 8 to 80 GeV of approximately 93E to the -2.91 power electrons/sq m/sec per sr/GeV. The results are compared with those of previous experiments as well as with the spectrum obtained for galactic nonthermal radiation. It is concluded that a 'clumpy' magnetic field proportional to the square root of matter density is consistent with measurements of high-energy electrons and synchrotron radiation toward the center of the Galaxy, that a gradual steepening of the electron spectrum relative to the proton spectrum is consistent with an electron lifetime of 1 million years, and that the density of cosmic-ray nucleons and electrons should be essentially uniform throughout the Galaxy if the nucleons have the same lifetime as the electrons and if they traversed 4 to 5 g/sq cm in that lifetime.

Freier, P.↗
NASA NTRS1977

Gamma-ray astronomy in the medium energy (10-50 MeV) range

To observe the medium energy component of the intense galactic center gamma-ray emission, two balloon flights of a medium energy gamma-ray spark chamber telescope were flown in Brazil in 1975. The results indicate the emission is higher than previously thought and above the predictions of a theoretical model proposed.

Kniffen, D. A.↗
NASA NTRS1979

Cosmic ray isotope abundances from chromium to nickel

IRIS, a telescope consisting of a large-area precision Cerenkov detector, scintillators, spark chambers, and a passive stack of Lexan polycarbonate track detectors, was exposed to the primary cosmic radiation for 6.6 sq m sr hr in a balloon flight in 1976. This measurement has yielded the isotopic composition of the iron-group elements Cr, Mn, Fe, and Ni with an average mass resolution of 0.65 amu for the energies 320-500 MeV per amu at the detector. This experiment places the most severe constraints to date on deviation from solar-system composition of the source of the cosmic radiation. Upper limits of 10 percent are placed on the ratios Fe-54/Fe-56 and Fe-58/Fe-56, which are inconsistent with large departures from solar system source composition reported by other workers. The isotopic measurements of Fe and Ni preclude the possibility that these cosmic rays were produced in a single e-process zone. The mean mass of Mn is less than 55, indicating the presence of electron-capture species produced by spallation.

Tarle, G.↗
NASA NTRS1979

The time-of-flight system on the Goddard medium energy gamma-ray telescope

A scintillation counter time of flight system, incorporated into the Goddard 50 cm by 50 cm spark chamber gamma ray telescope is described. The system, which utilizes constant fractions timing and particle position compensation and digitizes up to 10 ns time differences to six bit accuracy in less than 500 ns is analyzed. The performance of this system during balloon flight is discussed.

Ross, R. W.↗
NASA NTRS1981

Observations of 1-30 MeV gamma rays from the galactic center

Preliminary results are reported for gamma ray observations of the galactic center region made during a 15-hour balloon flight from Alice Springs, Australia on April 18, 1979. The observations were carried out with the UGR double-scatter gamma-ray telescope at energies of 1 to 30 MeV. The observations are compatible with a galactic source of approximately equal brightness along the region of system II galactic longitudes between 300 and 60 deg. The energy distribution joins smoothly to previous spark chamber results at energies above 30 MeV and to scintillator results below 1 MeV. It appears to be a combination of nuclear gamma ray lines superimposed on a power-law bremsstrahlung spectrum. The metastable C-12 line at 4.4 MeV appears to be present with a significance of about 16 standard deviations. The flux in the line is 0.0006 + or - 0.0003 photons/sq cm per sec per rad. The oxygen line at 6.1 MeV does not seem to appear significantly above background.

Zanrosso, E.↗
NASA NTRS1981

Laser measuring system for incremental assemblies

Wire-wrapped frame assemblies used in spark chambers and the like can be measured using a system which utilizes a laser, an interferometer, and a retroreflector to precisely measure distance. A light source and a photodetector are located adjacent the incremental assembly and mounted on a movable carriage. The interferometer is also mounted on the movable carriage, while the laser and retroreflector are positioned at either end of the carriage track. The carriage is moved along one edge of the incremental assembly between the retroreflector and the laser, and as the carriage is moved, the light from the light source to the photodetector is interrupted. This produces a trigger command to a control unit which in turn causes a distance measurement to be made. A printout is provided for each sampling trigger command to list such items as ideal position, actual position and amount of error.

Etzel, J. G.↗
NASA NTRS1982

Measurements of galactic plane gamma ray emission in the energy range from 10 - 80 MeV

A spark chamber gamma ray telescope was developed and flown to observe diffuse gamma ray emission from the central region of the galaxy. The extension of observations down to 10 MeV provides important new data indicating that the galactic diffuse gamma ray spectrum continues as a power law down to about 10 MeV, an observation in good agreement with recent theoretical predictions. Data from other experiments in the range from 100 keV to 10 MeV show a significant departure from the extension of the power-law fit to the medium energy observations reported here, possibly indicating that a different mechanism may be responsible for the emissions below and above a few MeV. The intensity of the spectrum above 10 MeV implies a galactic electron spectrum which is also very intense down to about 10 MeV. Electrons in this energy range cannot be observed in the solar cavity because of solar modulation effects. The galactic gamma ray data are compared with recent theoretical predictions.

Bertsch, D. L.↗