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ABSTRACT: The low-energy reaction 14C(n,gamma)15C provides a rare opportunity to test indirect methods for the determination of neutron capture cross sections by radioactive isotopes versus direct measurements. It is also important for various astrophysical scenarios. Currently, puzzling disagreements exist between the 14C(n,gamma)15C cross sections measured directly, determined indirectly, and calculated theoretically. To solve this puzzle, we offer a strong test based on a novel idea that the amplitudes for the virtual 15C-->14C + n and the real 15F -->14O + p decays are related. Our study of this relation, performed in a microscopic model, shows that existing direct and some indirect measurements strongly contradict charge symmetry in the 15C and 15F mirror pair. This brings into question the experimental determinations of the astrophysically important (n,gamma) cross sections for short-lived radioactive targets.
Physical Review Letters 05/2006; 96(16):162501. · 7.37 Impact Factor
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ABSTRACT: The low-energy reaction C14(n,γ)C15 provides a rare opportunity to
test indirect methods for the determination of neutron capture cross
sections by radioactive isotopes versus direct measurements. It is also
important for various astrophysical scenarios. Currently, puzzling
disagreements exist between the C14(n,γ)C15 cross sections
measured directly, determined indirectly, and calculated theoretically.
To solve this puzzle, we offer a strong test based on a novel idea that
the amplitudes for the virtual C15→C14+n and the real
F15→O14+p decays are related. Our study of this relation, performed
in a microscopic model, shows that existing direct and some indirect
measurements strongly contradict charge symmetry in the C15 and F15
mirror pair. This brings into question the experimental determinations
of the astrophysically important (n,γ) cross sections for
short-lived radioactive targets.
Physical Review Letters 03/2006; 96(16):162501. · 7.37 Impact Factor
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ABSTRACT: The first terms of the effective range expansion are accurately determined with a small number of evaluations of the potential. The method is based on the R matrix theory with a Lagrange basis which leads to a simple meshlike approximation. It is valid for both neutral and charged collisions for arbitrary partial waves. The accuracy of the algorithm is illustrated with an analytically solvable example, with different cases of potential scattering and in particular with the Paris and Bonn nucleon-nucleon potentials.
Phys. Rev. C. 12/2000; 63(1).
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ABSTRACT: The elastic α + 8He phase shifts are calculated with a two-centre generator-coordinate method. The microscopic α and 8He internal wave functions are defined in the harmonic-oscillator model. Bound states and resonances of 12Be are obtained. Among them, a 4+ resonance with a molecular structure should be observable in elastic scattering. The parity dependence of the microscopic
phase shifts is analyzed by fitting them with simple potentials. The odd-even effect is similar in the α + 8He and α + 6He phase shifts for low partial waves but decreases more rapidly with increasing orbital momentum for α + 8He.
Few-Body Systems 01/2000; 29(1):131-141. · 1.44 Impact Factor
