Dispersion relations in the nuclear optical model

Quesada, J. M.; Capote, R.; Molina, Alberto; Lozano, M.

doi:10.1016/s0010-4655(03)00157-7

Cited by 26 publications

(34 citation statements)

References 9 publications

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“…The optical model code OPTMAN [39,40] was used for OMP parameter fitting. Originally the code did not include dispersion terms, so numerical [41] and analytical solutions [42,43] of dispersion relations were implemented within the OPTMAN code. We used symmetric surface and nonsymmetric volume imaginary absorptive potentials; therefore we initially adjusted 16 parameters, namely V 0 , λ HF , and C viso , which define the smooth energy dependence of the real volume potential; W 0 , C wiso , B s , C s and A v , B v , E a , which define the surface and volume absorptive potentials, respectively; and six geometrical parameters (r HF , a HF , r v , a v , r s , a s ).…”

Section: Summary Of the Experimental Databases And Parameter Fitmentioning

confidence: 99%

Is a global coupled-channel dispersive optical model potential for actinides feasible?

et al. 2005

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An isospin-dependent coupled-channel optical model potential containing a dispersive term with a nonlocal contribution is used to simultaneously fit the available experimental database (including strength functions and scattering radius) for neutron and proton scattering on strongly deformed 238 U and 232 Th nuclei. The energy range 0.001-200 MeV is covered. A dispersive coupled-channel optical model (DCCOM) potential with parameters that show a smooth energy dependence and energy-independent geometry are determined from fits to the entire data set. Calculations using the obtained DCCOM potential reproduce measured total cross-section differences between 232 Th and 238 U within experimental uncertainty. The isovector terms and the observed very weak dependence of the geometrical parameters on mass number A allow us to extend the derived potential parameters to neighboring actinide nuclei with great confidence.

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Section: Summary Of the Experimental Databases And Parameter Fitmentioning

confidence: 99%

Is a global coupled-channel dispersive optical model potential for actinides feasible?

et al. 2005

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“…Originally the code did not include dispersion terms, so numerical [67] and analytical solutions [46,68] of dispersion relations were implemented within the OPTMAN code. We were using symmetric surface and nonsymmetric volume imaginary absorptive potentials according to Eq.…”

Section: Parameter Fittingmentioning

confidence: 99%

Dispersive coupled-channel analysis of nucleon scattering fromTh232up to 200 MeV

et al. 2005

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An isospin-dependent coupled-channels optical model potential containing a dispersive term (including nonlocal contribution) is used to simultaneously fit the available experimental database (including strength functions and scattering radius) for neutron and proton scattering on strongly deformed 232 Th nucleus. The energy range 0.001-200 MeV is covered. A dispersive coupled-channel optical model potential with parameters that show a smooth energy dependence and energy independent geometry are determined from fits to the entire data set. Dispersive contribution is shown to be the dominant Coulomb correction to the proton real potential below the Coulomb barrier. Inclusion of nonlocality effects in the absorptive volume potential and its corresponding dispersive contribution to the real potential is needed to achieve an excellent agreement above 100 MeV.

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“…(21) and (22) results in a dispersion relation that must be calculated directly from Eqs. (12) and (13) and separates into three additive terms [71,72]. Therefore, we write the dispersive volume correction in the form…”

Section: B High-energy Behavior Of the Volume Absorptionmentioning

confidence: 99%

Nucleon scattering on actinides using a dispersive optical model with extended couplings

et al. 2016

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The Tamura coupling model [Rev. Mod. Phys. 37, 679 (1965)] has been extended to consider the coupling of additional low-lying rotational bands to the ground-state band. Rotational bands are built on vibrational bandheads (even-even targets) or single-particle bandheads (odd-A targets) including both axial and nonaxial deformations. These additional excitations are introduced as a perturbation to the underlying axially symmetric rigid-rotor structure of the ground-state rotational band. Coupling matrix elements of the generalized optical model are derived for extended multiband transitions in even-even and odd-A nuclei. Isospin symmetric formulation of the optical model is employed. A coupled-channels optical-model potential (OMP) containing a dispersive contribution is used to fit simultaneously all available optical experimental databases including neutron strength functions for nucleon scattering on 232 Th, 233,235,238 U, and 239 Pu nuclei. Quasielastic (p,n) scattering data on 232 Th and 238 U to the isobaric analog states of the target nucleus are also used to constrain the isovector part of the optical potential. Lane consistent OMP is derived for all actinides if corresponding multiband coupling schemes are defined. For even-even (odd-A) actinides almost all low-lying collective levels below 1 MeV (0.5 MeV) of excitation energy are coupled. OMP parameters show a smooth energy dependence and energy-independent geometry. A phenomenological optical-model potential that couples multiple bands in odd-A actinides is published for a first time. Calculations using the derived OMP potential reproduce measured total cross-section differences between several actinide pairs within experimental uncertainty for incident neutron energies from 50 keV up to 150 MeV. The importance of extended coupling is studied. Multiband coupling is stronger in even-even targets owing to the collective nature of the coupling; the impact of extended coupling on predicted compound-nucleus formation cross section reaches 5% below 3 MeV of incident neutron energy. Excitation of multiple bands in odd-A targets is weaker owing to the single-particle nature of the coupling. Coupling of ground-state rotational band levels in odd-A nuclei is sufficient for a good description of the compound-nucleus formation cross sections as long as the coupling is saturated (a minimum of seven coupled levels are typically needed).

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Dispersion relations in the nuclear optical model

Cited by 26 publications

References 9 publications

Is a global coupled-channel dispersive optical model potential for actinides feasible?

Is a global coupled-channel dispersive optical model potential for actinides feasible?

Dispersive coupled-channel analysis of nucleon scattering fromTh232up to 200 MeV

Nucleon scattering on actinides using a dispersive optical model with extended couplings

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