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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: 25.70.Np ; 25.70.Cd
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Inclusive energy spectra and cross sections of reaction products close to the14N projectile (11C,12C,13C,15N and15O) have been measured in the angular rangeθ L =1.2°–4.2° at an incident energy of 60 MeV/u for five different target nuclei (12C,27Al,58Ni,90Zr and208Pb). Two components are found to be systematically present in the energy spectra of the carbon isotopes, the first similar to that observed at relativistic energies and the second shifted down in energy characteristic for a very dissipative process. The dependence of the differential and integrated cross sections on the target mass indicates that the two-body final channels (14N,13C), (14N,15N) and (14N,15O) are strongly correlated to the fragmentation channels.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-601X
    Keywords: 21.10.Dr ; 25.70.Cd ; 27.20.+ n
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The mass of10Li has been measured with two different reactions:9Be(13C,12N)10Li,E Lab=336 MeV, and13C(14C,17F)10Li,E Lab=337 MeV. The mass excess of 33.445(50) MeV is deduced from theQ-value measurement.10Li is found to be particle-unstable with respect to one-neutron emission by 0.42(5) MeV. In the analysis of the first reaction a low lying excited state is found at 0.38(8) MeV. This state and the ground state can be most probably identified as the 1+/2+-doublet coupled from the [π 1p3/2 ⊗ν 1p 1/2] configuration, the 1+-state being the ground state. The (13C,12N)-reaction populates the 1+-state strongly due to a spin-isospin-flip character of the dominant part of the transition amplitude. The 2+-member corresponds to the mass given by Wilcox et al. A second excited state is observed at 4.05(10) MeV with a width of 0.7(2) MeV, it can be associated with theν 1d 5/2-strength. The second reaction is fully supporting the interpretation of the ground state doublet. The excited state at 4.05 MeV is not observed in this reaction and indeed it should not, because the reaction does not populate in first order excited neutron configurations. The levels are well described by mean field calculations including pairing correlations. The lowest resonance in the calculations is theν 1/2−-configuration, whereas theν 1/2+-configuration shows at the neutron threshold a strong non-resonant contribution.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1434-601X
    Keywords: 24.10.-i ; 24.10.Eq ; 24.20.Ht ; 25.70.Cd
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Elastic, inelastic scattering as well as one-neutron transfer channels have been measured over a wide angular range for systems16O+16O at the incident energy of 350 MeV and20Ne+12C at 390 MeV, respectively, using the Q3D magnetic spectrometer. In both cases differential cross sections have been measured down to about 50 nb/sr (or dσ/dσ R≤10−4) at large angles. For the16O+16O system refractive contributions are found at the level of these cross sections, whereas in the20Ne+12C case a steeper decrease of the differential cross section with the angle is observed and the refractive contribution can not be determined. The elastic scattering data have been analyzed using standard Woods-Saxon potentials and potentials calculated in different versions of the double-folding model. Some properties of these potentials are tested in the calculations for inelastic scattering and one-neutron transfer within the DWBA. With the refractive pattern observed for the16O+16O system, the scattering and transfer data are found to be sensitive to the interaction potential at small internuclear distances down to about 2.5 fm.
    Type of Medium: Electronic Resource
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  • 5
    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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  • 6
    ISSN: 1434-601X
    Keywords: 21.10.Dr ; 25.70.Cd ; 27.20.+n
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The mass of 13 Be has been measured with the reaction 13 C(14 C,14 O)13 Be at E Lab =337 MeV. A Q-value of Q 0=−37.02(5) MeV was obtained and the mass excess is M.E.=35.16(5) MeV. If the observed line corresponds to the ground state,13 Be is particle unstable with respect to the oneneutron emission by 2.01 MeV. The observed line width of 0.3(2) MeV supports an assignment ofJ π=5/2+ or 1/2−, but excludesJ π=1/2+. An excited state is seen at 3.12(7) MeV; there are indications of a second excited state at 6.5(2) MeV.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 330 (1988), S. 227-228 
    ISSN: 1434-601X
    Keywords: 21.10.Dr ; 25.70.Cd ; 27.20.+n
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract First results of the double-charge-exchange reaction9Be(13C,13O)9He, ELab=380 MeV, are presented. The ground state and an excited state at 3.8 MeV are clearly seen. A preliminary value of the9He mass excess is obtained: 41.5±0.6 MeV. Spectra of of the9Be(13C,14O) He-reaction have been measured with high resolution. The ground state transition appears as a pronounced sharp peak, but no other narrow peaks are observed.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1434-601X
    Keywords: 21.10.Dr ; 25.70.Cd ; 27.40.+ z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The mass of57Cu has been measured with the58Ni(14N,15C)-reaction at 150 MeV incident energy with theQ 3D-spectrometer. The reaction has been selected after a careful inspection of the DWBA-expression for the cross section with respect to the highest weighting factors for spins andl-transfer. Cross sections of several μb/sr have been obtained. TheQ-value has been measured to beQ 0=−19.90 (4) MeV and the57Cu mass excess is −47 340 (40) keV. Four lines of excited states have been observed up to 5.7 MeV. These states have a structure of single particle character, since57Cu consists of a doubly closed core with N=Z=28 and a proton outside, and states up to the 2d 5-shell are observed.
    Type of Medium: Electronic Resource
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