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  • Electronic Resource  (3)
  • 24.10-i  (1)
  • 24.10.−i  (1)
  • 70cd  (1)
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  • Electronic Resource  (3)
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  • 1
    ISSN: 1434-601X
    Keywords: 24.10.−i ; 25.70.Cd
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The elastic and inelastic scattering and the neutron transfer have been measured for the systems12C +12C and13C +12C at 20MeV/N up to θcm= 60° with theQ3D -spectrometer. The angular distributions of the elastic scattering show an enhanced cross section at angles larger than 40°. It can be identified as refractive scattering with the clear signature of a nuclear rainbow.L-cut-off calculations show that these contributions come fromL-values which are significantly lower than the grazingL-value. The deflection function has a broad minimum in thisL-range which is typical for rainbow scattering. TheS-matrix is decomposed by a phenomenological parametrization into a refractive and a diffractive part. The interference of these amplitudes plays an important role in the rainbow enhancement. The spatial localization of the refractive scattering is deduced from the turning points of the corresponding trajectories; a localization between 2.5 fm and 4 fm is found. Semi-classical calculations with complex trajectories in the single-turning-point approximation show good agreement with the quantummechanical calculations. Refractive contributions are not observed in the inelastic scattering. This can be explained by reducing the strength of the conventional collective form factor in the internal region. In contrast to this the enhancement at large angles is seen in the one-neutron transfer channels where the refractive scattering is dominant. This is the first observation of such contributions to heavy-ion transfer reactions.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-601X
    Keywords: 24.10-i ; 25.70.Cd
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Proton and neutron transfer populating low-lying states have been studied in the system144Sm+88Sr at an energy below the Coulomb barrier. The experimental cross sections for the single proton transfer are well reproduced by DWBA-calculations using spectroscopic information from light ion reactions. The two-proton transfer appears enhanced relative to the uncorrelated sequential transfer of single protons. The same holds for the transfer of proton pairs, the enhancement is kept for the second pair. This is interpreted as a supercurrent between two superfluid nuclear proton-pair wave functions: more mass and charge is transported per time unit in pairs than by single nucleons. Neutron transfer is observed with large cross sections and is found to contribute to the energy loss observed in the transfer reactions. For mixed proton-neutron transfers the sequential nature of the transfer reactions is established in a similar way as for the two-proton and two-neutron transfer; in the latter case no enhancement is observed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-601X
    Keywords: 25 ; 70cd
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experimental results for neutron transfer in the system112Sn+120Sn are presented for three incident energies 4.25, 4.55 and 4.8 MeV/u. Final states are not resolved, however, the data represent transitions between low-lying states. The data are used to extract transfer probabilities and form factors for neutron transfer between low-lying states. A DWBA analysis gives a quantitative description of the observed overall cross section for one-neutron transfer. The enhancement of the two neutron transfer is discussed using semiclassical arguments; in this context additional data for the systems86Kr+208Pb,58Ni+208Pb,136Xe+238U and208Pb+238U are discussed. The general features of quasielastic transfer probabilities defined in a macroscopic way by an energy resolution of ca. 5–10 MeV, which is so far the only experimental possibility, are shown to give meaningful information on single nucleon and pair transfer between heavy nuclei. The latter point is also supported by coupled channel calculations for the transfer flux in these reactions and it is shown that a strong coupling situation is only reached at distances, where very strong absorption due to deeply inelastic reactions has set in.
    Type of Medium: Electronic Resource
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