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  • 1980-1984  (3)
  • 1975-1979
  • 1983  (2)
  • 1980  (1)
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  • 1980-1984  (3)
  • 1975-1979
Year
  • 1
    Electronic Resource
    Electronic Resource
    Steady flow approximations to the heliumR-process (1983)
    Springer
    Astrophysics and space science 91 (1983), S. 221-234 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract R-process yields for a helium layer have been calculated within a network of 6033 heavy nuclei using a steady flow approximation. The calculation of the neutron capture cross sections has been improved. The beta decay rates computed by Klapdor and his colleagues have been used in the calculation. We find that ther-process yield peaks near mass numbers 80 and 130 require a neutron number density of approximately 1020 cm−3 and a freezing time comparable to or less than 0.1 s. The peak near mass number 195 requires a neutron number density of about 1021 cm−3 and a freezing time comparable to or less than about 0.01 s. The individual yield features of the steady flowr-process depend entirely upon the neutron capture cross sections of the nuclei along the flow path and the beta decay rates, which can shift the flow path and thereby introduce inappropriate capture cross sections into the determination of the yields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00656111
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Beta-delayed fission and neutron emission: Consequences for the astrophysicalr-process and the age of the galaxy (1983)
    Springer
    The European physical journal 309 (1983), S. 301-317 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Beta-delayed neutron emission and beta-delayed fission probabilities (P n andP β d j ) were calculated for neutron-rich nuclei between the beta stability line and the neutron-drip line in the range 10≦Z≦100 and 75≦Z≦100, respectively. These results were obtained by applying recentβ-strength function calculations, fission barrier height predictions, and a neutron optical potential from infinite nuclear matter calculations. An area of ∼100% fission probability is predicted around Z=94,N=168 extending beyond the well-known island of spontaneous fission in that region. Astrophysicalr-process calculations were performed including the calculatedP n and Pβ d f values. This puts the method to determine the age of the Galaxy by the actinide chronometers on a reliable basis. An excellent overall agreement with the observedr-abundance distribution is obtained. The predictedr-process production ratios for the Chronometrie pairs232Th/238U,235U/238U and244Pu/238U result in an age of the Galaxy oft G =(20.8± 4 2 )×109 a, which is by almost a factor two larger than earlier predictions by this method, but in accordance with recent astronomical observations from globular clusters. The predicted island of 100%β-delayed fission acts as a sink to ther-process with the consequence that no superheavy elements are produced in nature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01413833
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Investigation of theβ +-decay of105,106,109In and of100,102Ag (1980)
    Springer
    The European physical journal 298 (1980), S. 21-29 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Isomers in the nuclei100Ag (I=5+),102Ag (I=5+),105In (I=9/2+),106In (I=6+),108In (I=6+) were selectively populated by the reactions90Zr(19F,xnγ),92Mo(19F, 2pnγ),92Mo(12C,pxnγ),90Zr(19F,α3nγ) atE lab=72 and 66MeV, and their (β ++EC)-decay was studied with an Anticomptonγ-spectrometer. Spins of the beta-decaying isomers are determined. The results obtained for the beta strength functions are discussed as well as new information on the structure of the neutron-deficient even-even daughter nuclei nearZ=50.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01416024
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    Paper (German National Licenses)
    Fulltext
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