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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

The NASA cosmic ray program for the 1990's and beyond

The interim report of the 1989 NASA Cosmic Ray Program Working Group is presented. The report summarizes the cosmic ray program for the 1990's, including the recently approved ACE, Astromag, HNC, POEMS, and SAMPEX missions, as well as other key elements of the program. New science themes and candidate missions are identified for the first part of the 21st century, including objectives that might be addressed as part of the Human Exploration Initiative. Among the suggested new thrusts for the 21st century are: an Interstellar Probe into the nearby interstellar medium; a Lunar-Based Calorimeter to measure the cosmic ray composition near 10 exp 16 eV; high-precision element and isotope spectroscopy of ultraheavy elements; and new, more sensitive studies of impulsive solar flare events.

Ahlen, S. P.↗
NASA NTRS1974

Search for antinuclei in the primary cosmic rays

Results of a search for primary cosmic-ray antinuclei with charges 2 less than or equal to Z less than or equal to 26 with rigidities above 5 GV/c using a second-generation superconducting magnetic spectrometer with an average bending power of 5.1 kG-m. The addition of new data doubles the sample of cosmic-ray nuclei previously reported and greatly increases the percentage of the more highly charged nuclei.

Smoot, G. F.↗
NASA NTRS1987

Large-scale fluctuations between 13 AU and 25 AU and their effects on cosmic rays

The reasons for the temporal and latitudinal large-scale fluctuations in the magnetic-field strength observed between 13 and 25 AU by Voyagers 1 and 2 in 1984-1985, and their effect on the cosmic ray intensity profile are investigated. The study of low-frequency and intermediate-frequency fluctuations determined from magnetic-field-intensity profile suggests the presence of discontinuities near the equator during both years. The intensity of cosmic ray nuclei of greater than 75 MeV during 1984 was found to fluctuate about a constant value, because the decreases of intensity caused by the passage of large merged interaction regions balanced the increases of intensity associated with rarefied regions. The intensity of cosmic ray nuclei above 75 MeV increased during 1985 because there were few large interactions then. The cosmic ray intensity increased more rapidly at low than at high latitudes. The model of Burlaga et al. (1985) was found to provide good first-order fits to the cosmic ray intensity profiles.

Burlaga, L. F.↗
NASA NTRS1980

Silver isotopic anomalies in iron meteorites - Cosmic-ray production and other possible sources

Sources of excess Ag-107 observed in iron meteorites are investigated with emphasis on reactions of cosmic-ray particles with palladium. Cross sections for the production of the silver isotopes from palladium by energetic cosmic-ray particles are estimated to calculate spallogenic production rates relative to that of Mn-53 from iron. The upper limits for the production rates of Ag-107 and Ag-109 by energetic galactic cosmic-ray particles are 690 and 270 atoms/min/kg(Pd), respectively, and the maximum rate for making excess Ag-107 by spallation reactions is 400 atoms/min/kg(Pd). The excess Ag-107 cannot be produced by a long exposure to cosmic-ray particles, and because it is harder to make the amount of Pd-107 observed in the iron meteorites by an early intense proton irradiation than it is to make the Al-26 observed in other meteorites, it is concluded that the excess Ag-107 is due to the decay of nucleosynthetic Pd-107 in the iron meteorites.

Reedy, R. C.↗
NASA NTRS1975

The isotopic composition of galactic cosmic ray Li, Be, and B

New measurements are reported of the isotopes of cosmic-ray Li, Be, and B and of the elements C, N, and O, with cosmic ray telescopes on board the IMP-7 and IMP-8 satellites during 1973-74 in the energy range 35-210 MeV/nucleon. High mass resolution and stability together with a set of data more extensive than in previous experiments lead to a clear isotopic separation. The measured isotopic and chemical abundances provide a stringent test for models of interstellar propagation and solar modulation. We find not only that for a steady state propagation and solar modulation model all light isotopes and medium element abundances are explained by 5 g/sq cm average pathlengths, as was earlier found from element analysis, but that also these results, taken along with our Be-10 measurements, indicate a longer lifetime for cosmic rays than predicted by the usual assumption of an average interstellar density of 1 to 3 atoms/cu cm.

Garcia-Munoz, M.↗
NASA NTRS1984

Evidence that the anomalous cosmic-ray component is singly ionized

Data from the Cosmic Ray Subsystem on the Voyager spacecraft were used to measure the spectra of He, C, N, O, and Ne with 4-124 MeV per nucleon (for O) during solar minimum conditions near the end of 1977. By subtracting both a low-energy interplanetary component and the high-energy galactic component, the energy spectra of the 'anomalous' cosmic-ray species He, N, O, and Ne are determined. The energy dependences of such spectra are found to depend upon the charge state of the particles, their source spectra, and the rigidity dependence of the diffusion coefficient. If the source spectra at the boundary of the modulation region have similar power-law energy dependences, then the observed energy spectra indicate that the anomalous particles are singly ionized.

Cummings, A. C.↗
NASA NTRS1991

The charge state of the anomalous component of cosmic rays

The ionic charge state of anomalous cosmic-ray oxygen has been determined by comparing measurements obtained inside the magnetosphere on a series of Cosmos satellite flights with simultaneous observations outside the magnetosphere from IMP 8 and ICE. A mean charge state of 0.9 + 0.3, - 0.2 is found for abount 10 MeV/nucleon anomalous oxygen, consistent with the model of Fisk et al. (1974), in which the anomalous cosmic rays originate from the neutral component of the local interstellar medium. This same approach gives results consistent with a mean charge state of +7 for solar energetic oxygen ions.

Adams, J. H., Jr.↗
NASA NTRS1985

Detectors for high energy cosmic rays on Spacelab

Two instruments designed to determine the spectra of the individual cosmic-ray components at very high energies are described. One of these (CRNE) uses a combination of gas Cerenkov counters and transition radiation detectors for the cosmic-ray nuclei lithium to nickel; the other (TRIC) is optimized for the light cosmic rays (electrons, protons, helium) and uses a transition-radiation/ionization-calorimeter combination. The CRNE instrument, constructed at the University of Chicago, was delivered to NASA for a first Shuttle flight on Spacelab-2 in summer 1985. Some of the technical and programmatic requirements encountered during the hardware construction and integration are discussed, and the expected scientific return and the prospects of using such instrumentation on the Space Station are considered.

Lheureux, J.↗
DOE OSTI2023

Feasibility of Correlated Extensive Air Shower Detection with a Distributed Cosmic-Ray Network

We explore the sensitivity offered by a global network of cosmic-ray detectors to a novel, unobserved phenomenon: widely separated simultaneous extended air showers. Existing localized observatories work independently to observe individual showers, offering insight into the source and nature of ultrahigh-energy cosmic rays. However no current observatory is large enough to provide sensitivity to anticipated processes such as the Gerasimova–Zatsepin effect or potential new physics that generate simultaneous air showers separated by hundreds to thousands of kilometers. A global network of consumer electronics (the Cosmic Rays Found In Smartphones (CRAYFIS) experiment), may provide a novel opportunity for observation of such phenomena. Two user scenarios are explored. In the first, with maximal user adoption, we find that statistically significant discoveries of spatially separated but coincident showers are possible within a couple years. In the second, more practical adoption model with 10 6 active devices, we find a worldwide CRAYFIS to be sensitive to novel "burst" phenomena where many simultaneous extensive air showers (EAS) occur at once.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1966

Charge ratio of cosmic ray electrons.

Charge ratio of cosmic ray electrons, examining excitation of baryon resonances in high energy collisions with no exchange of isospin

ELECTRON COLLISION↗
NASA NTRS1972

Modulation of low-energy galactic cosmic rays over solar maximum /cycle 20/.

Low-energy (about 60 MeV/nucleon) galactic cosmic rays observed during the recent period of solar maximum are reviewed. For this particular cycle, a significant time lag between intensity changes in the low-energy and high-energy components has been observed. Several possible explanations of this 'hysteresis effect' are discussed. The cosmic-ray intensity gradients provided by Pioneer 10 are soon to be available and are expected to provide a more definite clue to this process of cosmic-ray modulation.

Van Hollebeke, M. A. I.↗
NASA NTRS1978

The mean mass of the abundant cosmic-ray nuclei from boron to silicon at 1.2 GeV per atomic mass unit

Results are presented for an investigation of cosmic-ray isotopic composition in which a balloon-borne instrument was used to perform an isotopic analysis of the abundant elements from B through Si in the energy range from 1.0 to 1.6 GeV/amu. The technique employed, which depends on the effect of earth's magnetic field on incoming cosmic rays, and reduction of the observational data are described in detail. Mean masses of the elements B, C, N, O, Ne, Mg, and Si are extracted from normalized Cerenkov spectra and evaluated in terms of the 'leaky box' model of galactic propagation and confinement. The implications of the results for cosmic-ray sources are shown to be consistent with the nucleosynthesis of certain isotopes in the cosmic rays in explosive carbon burning under the conditions of peak temperature, density, and neutronization expected in an explosion of a massive highly evolved star. The possibility of alternate interpretations is noted.

Dwyer, R.↗
DOE OSTI2021

Measurements of the time-dependent cosmic-ray Sun shadow with seven years of IceCube data: Comparison with the Solar cycle and magnetic field models

Observations of the time-dependent cosmic-ray Sun shadow have been proven as a valuable diagnostic for the assessment of solar magnetic field models. Here, seven years of IceCube data are compared to solar activity and solar magnetic field models. A quantitative comparison of solar magnetic field models with IceCube data on the event rate level is performed for the first time. Additionally, a first energy-dependent analysis is presented and compared to recent predictions. We use seven years of IceCube data for the moon and the Sun and compare them to simulations on data rate level. The simulations are performed for the geometrical shadow hypothesis for the moon and the Sun and for a cosmic-ray propagation model governed by the solar magnetic field for the case of the Sun. We find that a linearly decreasing relationship between Sun shadow strength and solar activity is preferred over a constant relationship at the 6.4σ level. We test two commonly used models of the coronal magnetic field, both combined with a Parker spiral, by modeling cosmic-ray propagation in the solar magnetic field. Both models predict a weakening of the shadow in times of high solar activity as it is also visible in the data. We find tensions with the data on the order of 3σ for both models, assuming only statistical uncertainties. The magnetic field model CSSS fits the data slightly better than the PFSS model. This is generally consistent with what is found previously by the Tibet AS-γ Experiment; a deviation of the data from the two models is, however, not significant at this point. Regarding the energy dependence of the Sun shadow, we find indications that the shadowing effect increases with energy during times of high solar activity, in agreement with theoretical predictions.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1981

High-resolution observations of the isotopic composition of carbon and silicon in the galactic cosmic rays

High resolution satellite observations of the galactic cosmic rays (approximately 100-300 MeV/amu) have yielded determinations of near-earth isotopic compositions, which are presented: (C-13)/(C-12) = 0.070 + or - 0.006; (Si-29)/(Si-28) = 0.109(+0.024, -0.014); and (Si-30)/(Si-28) = 0.084(+0.020, -0.014). Using a standard propagation model, source values greater than solar are derived for each of these ratios. The (C-13) excess may be the result of cross section uncertainties, but the (Si-29) and (Si-30) appear to reflect real differences between the galactic cosmic-ray source and the solar system.

Wiedenbeck, M. E.↗
NASA NTRS1981

The elemental and isotopic composition of cosmic rays - Silicon to nickel

The reported observations were made with the aid of the Cosmic Ray Isotope Instrument System (CRISIS) which had been designed to detect and resolve the isotopes of cosmic ray nuclei with atomic numbers equal to or greater than 10. The CRISIS detector was flown on a balloon launched from Aberdeen, South Dakota on 1977 May 20. The period 1977 May 19-22 has been classified by Mason et al. (1979) as one of 'superquiet' solar activity, characterized by the lowest fluxes of low-energy solar particles ever observed. The obtained results are presented in a number of graphs and tables. It was found that the elemental and isotopic abundances of Si are solar-like. Elemental S is underabundant in the cosmic rays by a factor of approximately 3 relative to the solar system, but its isotopic composition resembles the solar composition with S-32 being the dominant isotope. Elemental Ar is virtually absent in the source, and the observed isotopic composition is consistent with a secondary origin. Elemental Ni has a solar-like abundance.

Young, J. S.↗
NASA NTRS1974

The charge and isotopic composition of solar cosmic rays

The charge and isotopic composition of solar cosmic rays potentially contain a wealth of information on the acceleration and confinement of energetic particles at the sun. As the experimental techniques have improved and with the increasing number of measurements, this potential is now being realized. It is convenient to divide the composition studies into three areas: (1) helium-iron, with energies above 10 MeV per nuc; (2) helium-iron, and the trans-iron elements, with energies below 2 MeV per nuc; (3) the isotopic composition. In the first area at energies above 10 MeV per nuc, the solar cosmic rays appear to provide a representative sample of the solar corona. At lower energies complex enhancement effects are noted. These increase with Z and decrease with energy.

Mcdonald, F. B.↗