Evidence for a progressive failure of the double folding model at energies approaching the Coulomb barrier

Lilley, J.S.; Fulton, B.R.; Nagarajan, M.A.; Thompson, I. J.; Banes, David

doi:10.1016/0370-2693(85)90830-5

Cited by 122 publications

(34 citation statements)

References 10 publications

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“…Such a change in the characteristics have been observed by Lilley et al [13] in the elastic scattering of 160 on 2°8pb at energies close to the Coulomb barrier.…”

Section: P2(r)=rzop(r )supporting

confidence: 65%

Coupled channel effects in the scattering of 6,7Li BY 58Ni

1985

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Using a single-particle description of 6.7 Li and Woods-Saxon generated wave functions for 58 Ni matter density distribution, the diagonal and transition densities are calculated. Folding these densities with the M3Y effective interaction, the coupling and diagonal potentials are obtained. Coupled channel calculations for 6'TLi on 58 Ni at bombarding energies in a range from 12 to 74 MeV are performed. It is shown that the predictions of the coupled channel calculations are consistent with those of optical model calculations using folded potentials renormalized by a factor 0.6 in the entire range of energies.In recent years the scattering of light heavy ions such as 6'7Li and 9Be have received considerable interest. This is due to the failure of the double folding potential [1] obtained from an effective nucleon-nucleon interaction [2], which have to be renormalized by a factor around 0.6 in order to fit the elastic scattering data for these nuclei.This anomaly has been attributed to break-up effects which become important due to the low break-up threshold of these nuclei [3]. This idea has been confirmed by calculations describing 6Li and 7Li, respectively, as (a + a) and (a + t) systems. It is found that to reproduce the elastic scattering data of 6'7Li in terms of the optical potentials of the target with the fragments of the projectile, the break-up states must be considered. The cluster model is also successful in explaining the behavior of polarized projectiles. It is shown [4] that the coupling effects between the clusterdescribed excited states have a very important effect on the tensor analyzing powers, even at very low energy. Of particular interest is the work of Sakuragi et al. [5], who use a detailed cluster description of 6Li, discretizing the continuum of break-up states in several bins for each relevant partial wave. The diagonal and transition potentials are obtained from an effective nucleonnucleon interaction convoluted with the target density and the corresponding projectile diagonal and transition density. It is shown that the main contribution on the elastic scattering comes from the resonances which affect mainly the real potential.Recently we have developed a single-particle description of 7Li [6], assuming a (0s)4(0p) 3 configuration in a single-particle well for the relevant states of 7Li. The different negative parity states of this nucleus are obtained by diagonalizing a residual hamiltonian, and the diagonal and 0370-2693/85/$ 03.30

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“…Such a change in the characteristics have been observed by Lilley et al [13] in the elastic scattering of 160 on 2°8pb at energies close to the Coulomb barrier.…”

Section: P2(r)=rzop(r )supporting

confidence: 65%

Coupled channel effects in the scattering of 6,7Li BY 58Ni

1985

Self Cite

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“…D, the real and imaginary parts of both DR and fusion polarization potentials determined from the present χ 2 analyses satisfy the dispersion relation [9,10] separately. Furthermore, the fusion potential exhibits the threshold anomaly as observed in heavy ion collisions involving tightly bound projectiles [24,25,26]. For the 6 Li+ 208 Pb system studied earlier [5] similar threshold anomaly for the fusion potential and the dispersion relation were observed.…”

Section: F Discussionsupporting

confidence: 53%

“…(17). Note that the energy variations seen in W F (E) and V F (E) are more rapid compared to those seen in W D (E) and V D (E), and are similar to those observed with tightly bound projectiles [24,25,26]. It is thus seen that the resultant V F (E) and W F (E) exhibit the threshold anomaly.…”

Section: χ 2 Analysessupporting

confidence: 57%

Extended optical model analyses of elastic scattering and fusion cross section data for theLi7+Pb208system at near-Co

Udagawa

Kim

et al. 2007

Phys. Rev. C

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Simultaneous χ 2 analyses previously made for elastic scattering and fusion cross section data for the 6 Li+ 208 Pb system is extended to the 7 Li+ 208 Pb system at nearCoulomb-barrier energies based on the extended optical model approach, in which the polarization potential is decomposed into direct reaction (DR) and fusion parts.Use is made of the double folding potential as a bare potential. It is found that the experimental elastic scattering and fusion data are well reproduced without introducing any normalization factor for the double folding potential and that both the DR and fusion parts of the polarization potential determined from the χ 2 analyses satisfy separately the dispersion relation. Further, we find that the real part of the fusion portion of the polarization potential is attractive while that of the DR part is repulsive except at energies far below the Coulomb barrier energy. A comparison is made of the present results with those obtained from the Continuum Discretized Coupled Channel (CDCC) calculations and a previous study based on the conventional optical model with a double folding potential. We also compare the present results for the 7 Li+ 208 Pb system with the analysis previously made for the 6 Li+ 208 Pb system.

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“…Secondly, the fusion potential is found to exhibit the threshold anomaly, as was observed for tightly bound projectiles [20,21,22], but the DR potential does not show a rapid energy variation, i.e., the threshold anomaly. Thirdly, at the strong absorption radius, the magnitude of the fusion potential was found to be much smaller than that of the DR potential.…”

Section: Introductionmentioning

confidence: 67%

Extended optical model analyses of elastic scattering and fusion cross sections for theLi6+Pb208system at near-Coulom

Udagawa

Kim

et al. 2007

Phys. Rev. C

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Based on the extended optical model approach in which the polarization potential is decomposed into direct reaction (DR) and fusion parts, simultaneous χ 2 analyses are performed for elastic scattering and fusion cross section data for the 6 Li+ 208 Pb system at near-Coulomb-barrier energies. A folding potential is used as the bare potential. It is found that the real part of the resultant DR part of the polarization potential is repulsive, which is consistent with the results from the Continuum Discretized Coupled Channel (CDCC) calculations and the normalization factors needed for the folding potentials. Further, it is found that both DR and fusion parts of the polarization potential satisfy separately the dispersion relation.

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Evidence for a progressive failure of the double folding model at energies approaching the Coulomb barrier

Cited by 122 publications

References 10 publications

Coupled channel effects in the scattering of 6,7Li BY 58Ni

Coupled channel effects in the scattering of 6,7Li BY 58Ni

Extended optical model analyses of elastic scattering and fusion cross section data for theLi7+Pb208system at near-Co

Extended optical model analyses of elastic scattering and fusion cross sections for theLi6+Pb208system at near-Coulom

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