The neutron optical potential

Hodgson, P. E.

doi:10.1088/0034-4885/47/6/001

Cited by 44 publications

(25 citation statements)

References 170 publications

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“…The respective curves employ the parameters of Table IV. FIG. 6. Capture cross section in the resonance region of 'Li.…”

Section: Thermal-neutron Capturementioning

confidence: 99%

“…resonance in a real potential well, but the parameters of this well must be energy dependent to correctly describe the cross section. Such energy dependence is known to be a requirement of optical-model potentials that give global descriptions of cross-section data in much heavier nuclei [6,7]. The calculation of the neutron-capture cross section for E1 transitions over the energy range up to several hundred keV is described in Sec.…”

Section: Introductionmentioning

confidence: 99%

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Direct and valence neutron capture byLi7

1991

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We have measured the cross section for neutron radiative capture by Li at thermal neutron energy as 45.4+3.0 mb. We have compared this value, and the available fast-neutron-capture cross-section data on Li, with directand valence-capture theory. The mechanism of direct capture involving simple neutron-orbital transitions within a potential well can adequately account for the magnitude of the thermal-neutron-capture cross sections and the shape of the fast-neutron-capture cross sections. We recommend that the capture cross sections from the theoretical calculation, instead of those from a recent measurement, be used for nuclear astrophysics calculations. If the fast-neutron-capture data are normalized at 25 keV to the theoretical value, the magnetic-dipole (M 1) radiation width of the 255-keV p-wave resonance can be deduced. It is in agreement with the value calculated from a valence theory for M1 capture, thus lending support for this neutron-capture mechanism as an important one, at least for light nuclei. We also find some evidence from our analysis of the total cross-section data for a possible energy dependence of the potential required to describe the almost pure single-particle s-wave resonances underlying the Li cross section.

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“…The respective curves employ the parameters of Table IV. FIG. 6. Capture cross section in the resonance region of 'Li.…”

Section: Thermal-neutron Capturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Direct and valence neutron capture byLi7

1991

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“…The bound-state energies were calculated using a central Woods-Saxon potential of radius 7.32 fro, diffuseness 0.65fm and depth 63.01MeV and 47.56 MeV for the protons and neutrons, respectively [18]. The scattering phase shifts were evaluated using a potential (also from [18]) that accurately describes nucleon scattering for energies up to e=200MeV. The scattering phase shifts were evaluated using a potential (also from [18]) that accurately describes nucleon scattering for energies up to e=200MeV.…”

Section: Calculationsmentioning

confidence: 99%

“…3). This is not a problem, providing that we regard the optical potential of [18] simply as a tool for reproducing experimentally obtained phase shifts, without necessarily being the physically correct potential. It is clearly important, especially in view of the lack of self-consistency in our approach, to use as good an optical potential as possible.…”

Section: Calculationsmentioning

confidence: 99%

Thermal properties of nuclei: The implications of Levinson's theorem

Dean

Mosel

1985

Z Physik A

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“…For the nuclear potential, we use a global fit to neutron scattering data given by Hodgson [11]. It consists of a real volume term plus an imaginary surface term.…”

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confidence: 99%

Energy dependence of11Li dissociation cross section

Sustich

1992

Z. Physik A - Hadrons and Nuclei

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The Coulomb breakup cross section of l~Li is calculated as a function of its bombarding energy. Comparison is made to cross sections at 790MeV/nucleon and 30 MeV/'nucleon. Low energy reactions on a high-Z target show a greatly enhanced Coulomb breakup cross section that is more sensitive to the distribution of dipole response strength than high energy reactions thus providing more structure information. PACS: 21.60.-n; 25.70.NpThe structure of the neutron-rich nucleus 11Li has been the subject of a great amount of recent discussion. Kobayashi et al. [13 have measured the breakup and total reaction cross sections for 800 MeV/nucleon 11Li on a variety of targets. More recently, Anne et al. [2] have also measured these cross sections at a lower beam energy of 30 MeV/nucleon. On a low-Z target (where the Coulomb effects are negligible), the unusually large total reaction cross section is a clear signal of an extended density distribution in 11Li. This is the so called "neutron halo". On a high-Z target, Coulomb excitation also contributes to the cross sections. The Coulomb breakup cross section can be directly related to the electric dipole response of l~Li [3, 43, and this can give much useful information on the nuclear structure.The two-neutron separation energy for ~Li is $2, = 0.25_+ 0.I0 MeV. This very weak binding allows these two valence neutrons to be found at large distances from the more tightly bound 9El core, thus forming the neutron halo. Furthermore, l~ is unbound by 0.80+ 0.25 MeV. Thus, the interaction between the two valence neutrons is as important as the mean field potential for the stability of ~ ~Li. Because of this, one expects a correlation to exist in the wave function of these valence neutrons. To examine the effect of this correlation, one must go beyond a mean field description. Cluster models [5][6][7] which consider a two body problem consisting of 9El core plus dineutron and three body models [-8, 9] which treat the 9Li + n + n system have been proposed.In this report, we will not focus too closely on specific structure models, but instead concentrate on what information can be extracted from the type of cross section measurements that have been made. Let us first consider the nuclear contribution to the cross sections. For reactions of ~lLi at 790 MeV/nucleon, we have previously developed a diffractive eikonal model [10] to calculate the nuclear contribution to the total reaction and 9Li + 2n breakup cross sections. It uses a purely imaginary eikonal phase determined from the target density and nucleon-nucleon cross section to calculate the absorption of the projectile wave function after passing the target at a given impact parameter. For reactions on a t2C target, where the Coulomb contributions are negligible, it does an excellent job of reproducing the experimental cross sections. Now we wish to consider the much lower beam energy of 30 MeV/nucleon. At this energy, one must allow for a real part of the eikonal phase in addition to the imaginary part. Consider a nucleon in an initial...

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The neutron optical potential

Cited by 44 publications

References 170 publications

Direct and valence neutron capture byLi7

Direct and valence neutron capture byLi7

Thermal properties of nuclei: The implications of Levinson's theorem

Energy dependence of11Li dissociation cross section

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