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  • 1975-1979  (12)
  • 1
    Electronic Resource
    Electronic Resource
    UH cosmic rays and solar system material: The elements just beyond iron (1977)
    Springer
    Astrophysics and space science 49 (1977), S. 47-81 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The origin of the elements from Cu to As in the UH (ultra-heavy) cosmic rays is investigated and related to current concepts of the nucleosynthesis of solar system material. The charge spectrum of the UH cosmic rays in the interval 29≤Z≤60 is studied via a fully developed propagation calculation for source abundances given by solar system material, ther-process, the massive-star core helium-burnings-process, and explosive carbon burning. None of these sources considered individually can explain the cosmic ray observations. However a combination of material produced in ther-process, the core helium-burnings-process and in explosive carbon burning provides a good representation of the experimental data. The cosmic-rayr-process is found to differ from solar systemr-process events by an underproduction of the low-massr-process peaks relative to theA∼195 peak. The large cosmicray abundance forZ=40–44 may be due to anr-process fission component, but this explanation is by no means certain. Improved cosmic-ray data, especially for Zn−Sr, can provide limits to the various source contributions. The model described here gives a consistent picture for the origin of both the cosmic rays and the solar system elements just beyond iron, and adds additional evidence for the importance of massive stars as a site of nucleosynthesis and the birthplace of the cosmic rays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00647076
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    Paper (German National Licenses)
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  • 2
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    UH cosmic rays and solar system material: The elements just beyond iron (1977)
    Springer
    Details
    Publication Date: 1977-06-01
    Print ISSN: 0004-640X
    Electronic ISSN: 1572-946X
    Topics: Physics
    Published by Springer
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    PAPER CURRENT
  • 3
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    Isotopic anomalies from neutron reactions during explosive carbon burning (1979)
    Institute of Physics
    Details
    Publication Date: 1979-09-01
    Print ISSN: 0004-637X
    Electronic ISSN: 1538-4357
    Topics: Physics
    Published by Institute of Physics
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    PAPER CURRENT
  • 4
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    The isotopes of neon in the galactic cosmic rays (1979)
    Institute of Physics
    Details
    Publication Date: 1979-09-01
    Print ISSN: 0004-637X
    Electronic ISSN: 1538-4357
    Topics: Physics
    Published by Institute of Physics
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    PAPER CURRENT
  • 5
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    Aluminum-26 production from a stellar evolutionary sequence (1978)
    Institute of Physics
    Details
    Publication Date: 1978-09-01
    Print ISSN: 0004-637X
    Electronic ISSN: 1538-4357
    Topics: Physics
    Published by Institute of Physics
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  • 6
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    Isotopic anomalies from neutron reactions during explosive carbon burning (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The heavy isotopic anomalies observed recently in the fractionation and unknown nuclear inclusions from the Allende meteorite are explained by neutron reactions during the explosive carbon burning (ECB). This model produces heavy anomalies in the same zone where Al-26 and O-16 are produced, thus reducing the number of source zones required for the isotopic anomalies. Unlike the classical r-process, the ECB n-process avoids the problem with the Sr anomaly and may resolve the problem of conflicting time scales between Al-26 and the r-process isotopes I-129 and Pu-244. Experimental studies of Zr and Ce isotopic composition are proposed to test this model.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 232
    Format: text
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  • 7
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    UH cosmic rays and solar system material - The elements just beyond iron (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The nucleosynthesis of cosmic-ray elements between the iron peak and the rare-earth region is examined, and compositional changes introduced by propagation in interstellar space are calculated. Theories on the origin of elements heavier than iron are reviewed, a supernova model of explosive nucleosynthesis is adopted for the ultraheavy (UH) cosmic rays, and computational results for different source distributions are compared with experimental data. It is shown that both the cosmic-ray data and the nucleosynthesis calculations are not yet of sufficient precision to pinpoint the processes occurring in cosmic-ray source regions, that the available data do provide boundary conditions for cosmic-ray nucleosynthesis, and that these limits may apply to the origin of elements in the solar system. Specifically, it is concluded that solar-system abundances appear to be consistent with a superposition of the massive-star core-helium-burning s-process plus explosive-carbon-burning synthesis for the elements from Cu to As and are explained adequately by the s- and r-processes for heavier elements.
    Keywords: SPACE RADIATION
    Type: Astrophysics and Space Science; 49; 1, Ju; June 197
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  • 8
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    The isotopes of neon in the galactic cosmic rays (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The paper examines the results obtained by the University of Chicago instrument on board the IMP 7 satellite used to measure the abundances of Ne-20 and Ne-22 in the galactic cosmic rays during 1973-1977, over the general energy range of 60-230 MeV per nucleon. It is reported that the instrument shows a mass resolution of 0.7 amu(sigma) which was confirmed by calibrating a backup instrument at the LBL Bevalac with separated beams of neon isotopes. Through the use of standard solar modulation and cosmic-ray propagation models, the cosmic-ray source ratio inferred is Ne-22/Ne-20 = 0.38 = or -0.07 which is significantly greater than the present solar system ratio. It is concluded that propagation effects or cross-section uncertainties cannot account for such a large abundance of Ne-22, and thus this measurement provides evidence that the cosmic rays come from a source region where the Ne-22 abundance is substantially greater than in solar system material.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; vol. 232
    Format: text
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  • 9
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    Isotopic anomalies from neutron reactions during explosive carbon burning (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The possibility that the newly discovered correlated isotopic anomalies for heavy elements in the Allende meteorite were synthesized in the secondary neutron capture episode during the explosive carbon burning, the possible source of the O-16 and Al-26 anomalies, is examined. Explosive carbon burning calculations under typical conditions were first performed to generate time profiles of temperature, density, and free particle concentrations. These quantities were inputted into a general neutron capture code which calculates the resulting isotopic pattern from exposing the preexisting heavy seed nuclei to these free particles during the explosive carbon burning conditions. The interpretation avoids the problem of the Sr isotopic data and may resolve the conflict between the time scales inferred from 1-129, Pu-244, and Al-26.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: NASA-CR-157924 , ATR-79(9552)-1
    Format: application/pdf
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  • 10
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    UH cosmic rays: Possible origin in massive stars (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The origin of the Z greater than 28, ultraheavy, cosmic rays in supernova explosions of massive stars is considered. For Z greater than 70, the UH data is dominated by an r-process source distribution, but for the elements just beyond iron, 29 or = Z less than 36, the data cannot be explained by any single process of nucleosynthesis. This problem is solved naturally in a massive star model by secondary neutron capture reactions occuring during core helium burning and during explosive carbon burning. Interstellar propagation calculations were performed with these episodes of synthesis as source distributions, and the results offer an explanation for the current UH cosmic-ray data. The heavy element synthesis during explosive carbon burning is reexamined using more realistic initial conditions given by the post-helium-burning configuration of the star. Effects of preferential acceleration are considered, and experimental tests are discussed.
    Keywords: SPACE RADIATION
    Type: Aerospace Corp. Compilation of Contrib. to the 15th Intern. Cosmic Ray Conf.; p 7-12
    Format: text
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