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  • 25.55.-e  (2)
  • 97.10.Cv  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 329 (1988), S. 243-254 
    ISSN: 1434-601X
    Keywords: 25.55.-e ; 27.10 ; 27.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The absolute cross section σ(E) of the3He(α, γ)7Be reaction has been measured fromE c.m. =195 to 686 keV. The studies employed both a supersonic jet gas target and an extended gas target, and were carried out by the observation of the prompt capture γ-ray transitions as well as the7Be residual nuclei. The absolute cross sections deduced from the capture γ-rays are in good agreement with most previous work and remove a discrepancy with other earlier work. In comparison, the σ(E) values obtained from the7Be residual nuclei are systematically higher, suggesting a small production of additional7Be by contaminant reactions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 333 (1989), S. 219-227 
    ISSN: 1434-601X
    Keywords: 21.60.Gx ; 25.55.-e ; 24.10.Eq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have performed a microscopic study of the3He(d,p) α reaction at astrophysical energies within the framework of the Resonating Group Method adopting three different effective nucleon-nucleon interactions. The calculations suggest that the low-energy3He(d,p) α cross section is in good approximation given by the contribution arising from the 3/2+ resonant state atE R =245 keV. In fact, the low-energy data can be better (and more physically) described by a single Breit-Wigner resonance parametrization than by a polynomial fit. Our fit to the3He(d,p) α cross section results in a noticeable reduction in the uncertainties of the resonance parameters of the 3/2+ resonant state as well as in a significantly improved extrapolation of the data to astrophysically important energies. On the basis of this extrapolation we were able to quantitatively deduce the enhancement of the low-energy cross section due to electron screening effects from the data of Krauss et al. and Engstler et al. These experimental enhancement factors were compared with various theoretical models which are all based on the Born-Oppenheimer approximation. As the models underestimate the observed enhancement we suggest that the theoretical study of electron screening effects requires a dynamical treatment.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 327 (1987), S. 461-468 
    ISSN: 1434-601X
    Keywords: 25.90 ; 97.10.Cv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effects of electron screening on the low-energy cross sections of nuclear fusion reactions of astrophysical interest have been studied within the Born-Oppenheimer approximation using a simplified model. These studies indicate that a significant enhancement of the cross sections can occur already at beam energies, which are about a factor 100 higher than the electron binding energies. Cross sections near such energies can now be measured, in some cases, and several examples are discussed. For an understanding of the low-energy data as well as for a reliable extrapolation of the cross sections (for bare nuclei) to lower energies, the effects of electron screening must be well understood.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1434-601X
    Keywords: 27.30.+t ; 97.10.Cv ; 97.10.Tk ; 97.30.Qt ; 98.58.Ca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nuclear levels of23Mg near and above the proton threshold were investigated with high resolution. A new level has been identified at 7.643 MeV (66 keV above the proton threshold) with a possible Jπ=(3/2, 5/2)+. Some other spin-parity and excitation-energy assignments are also made. These results enable the reaction rate estimate of22Na(p,γ)23Mg with much smaller uncertainties, which is critical for the Ne-E problem in nuclear astrophysics.
    Type of Medium: Electronic Resource
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