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

Capote, R.; Soukhovitskiĩ, E. Sh.; Quesada, J. M.; Chiba, Satoshi

doi:10.1103/physrevc.72.064610

Cited by 48 publications

(70 citation statements)

References 36 publications

(49 reference statements)

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“…What are the differences in calculated optical-model observables between the present model (PM) and previous works that used either SRM couplings [5,6] or rigid-rotor model (RRM) couplings [10,11]? The main difference between SRM and RRM is the aforementioned coupling of the non-GS vibrational bands with strength proportional to the "effective" deformations derived from the SRM parameters.…”

Section: Discussionmentioning

confidence: 99%

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Optical model with multiple band couplings using soft rotator structure

et al. 2017

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Abstract.A new dispersive coupled-channel optical model (DCCOM) is derived that describes nucleon scattering on 238 U and 232 Th targets using a soft-rotator-model (SRM) description of the collective levels of the target nucleus. SRM Hamiltonian parameters are adjusted to the observed collective levels of the target nucleus. SRM nuclear wave functions (mixed in K quantum number) have been used to calculate coupling matrix elements of the generalized optical model. Five rotational bands are coupled: the ground-state band, β-, γ -, non-axial-bands, and a negative parity band. Such coupling scheme includes almost all levels below 1.2 MeV of excitation energy of targets. The "effective" deformations that define inter-band couplings are derived from SRM Hamiltonian parameters. Conservation of nuclear volume is enforced by introducing a monopolar deformed potential leading to additional couplings between rotational bands. The present DCCOM describes the total cross section differences between 238 U and 232 Th targets within experimental uncertainty from 50 keV up to 200 MeV of neutron incident energy. SRM couplings and volume conservation allow a precise calculation of the compound-nucleus (CN) formation cross sections, which is significantly different from the one calculated with rigid-rotor potentials with any number of coupled levels. Coupled-channel optical model with soft-rotor couplingsTamura classical coupling model [1] has been recently extended to consider the coupling of collective rotational bands to the ground state band in even-even actinides including both axial and non-axial deformations [2][3][4]. These additional excitations were introduced as a perturbation to the underlying axial-symmetric rigid rotor structure of the ground state band (GSB) (i.e., K was considered a good quantum number characterizing all collective bands). However, it is well known that the rigid-rotor calculated energy of the levels overestimates the measured excitation energy with increasing excitation energy. For 238 U nucleus, the 10 + (12 + ) state is 6% (8.4%) higher in energy than predicted by the rigid-rotor model.A proper description of the energy of excited levels in actinides can be achieved by using a soft-rotator model (SRM) as demonstrated in Refs. [5,6]. SRM considers the stretching of the nucleus that lead to a higher momentum of inertia and lower excitation energies of high spin collective states in much better agreement with experimental data. Our goal is to use the SRM -reproducing the low-lying nuclear structure of even-even actinides with high accuracy -to predict coupling strengths and calculate corresponding matrix elements of the generalized dispersive optical model. The instant nuclear shape is described by small nonaxiality, and quadrupolar and octupolar departures a e-mail: dmart@sosny.bas-net.by from the axially symmetric equilibrium shape as follows λ=2,4,6,8 where R rr i is the rigid-rotor nuclear shape and δ R i -the shape perturbations, θ and ϕ are the angular coordinates in the body-fixed (intrin...

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Section: Discussionmentioning

confidence: 99%

“…The experimental data for nucleon interaction on 232 Th and 238 U targets coincide with the database used in our previous works [10,11]. A Lane consistent formulation of the generalized optical model [12] is used with dispersive integrals calculated analytically [13,14].…”

Section: Optical Model Parametersmentioning

confidence: 99%

Optical model with multiple band couplings using soft rotator structure

et al. 2017

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“…Our previously developed isospin-dependent DCCOMP for actinides [3,4] has been shown [7] to be approximately Lane consistent, and described the direct quasi-elastic (p,n) scattering to the IAS of the target nucleus. The corresponding coupling form-factors for the charge-exchange calculations using the dispersive coupled-channel potential were defined in Ref.…”

Section: Lane Consistency Of the Dccomp And Excitations Of The Isobarmentioning

confidence: 99%

“…A detailed formulation of the dispersive coupled-channel optical model potential was given in previous works [2][3][4]; a brief summary is given in the next Section. We focus in this contribution on the second area of development, namely on improving the model of nuclear structure used in coupledchannel calculations.…”

Section: Introductionmentioning

confidence: 99%

A dispersive optical model potential for nucleon induced reactions on²³⁸U and²³²Th nuclei with full coupling

Quesada

Soukhovitskiĩ

Capote

et al. 2013

EPJ Web of Conferences

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Abstract.A dispersive coupled-channel optical model potential (DCCOMP) that couples the ground-state rotational and low-lying vibrational bands of 238 U and 232 Th nuclei is studied. The derived DCCOMP couples almost all excited levels below 1 MeV of excitation energy of the corresponding even-even actinides. The ground state, octupole, beta, gamma, and non-axial bands are coupled. The first two isobar analogue states (IAS) populated in the quasi-elastic (p,n) reaction are also coupled in the proton induced calculation, making the potential approximately Lane consistent. The coupled-channel potential is based on a soft-rotor description of the target nucleus structure, where dynamic vibrations are considered as perturbations of the rigid rotor underlying structure. Matrix elements required to use the proposed structure model in Tamura coupled-channel scheme are derived. Calculated ratio R(U238/T h232) of the total cross-section difference to the averaged σ T for 238 U and 232 Th nuclei is shown to be in excellent agreement with measured data.

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“…Therefore low-lying rotational bands, built on vibrational band-heads for even-even and on single-particle bandheads for odd nuclei, need to be taken into account to describe neutron inelastic scattering on actinides. Authors were not able to find published optical model potentials for neutron scattering on odd actinides, even if many publications described applications to even-even actinides [3][4][5][6][7][8][9] dependent optical model potential for actinides [10][11][12] assuming a rigid rotor coupling of levels in the rotational ground state band. The coupling of vibrational bands improved the description of neutron scattering on even-even actinides in the energy region from 500 keV up to about 3 MeV, which is critical for fast neutron fission reactors, as was discussed at the WONDER 2012 workshop [13].…”

Section: Introductionmentioning

confidence: 99%

A Lane consistent optical model potential for nucleon scattering on actinide nuclei with extended coupling

Quesada

Capote

Soukhovitski

et al. 2016

EPJ Web of Conferences

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Abstract. An extension for odd-A actinides of a previously derived dispersive coupledchannel optical model potential (OMP) for 238 U and 232 Th nuclei is presented. It is used to fit simultaneously all the available experimental databases including neutron strength functions for nucleon scattering on 232 Th , 233,235,238 U and 239 Pu nuclei. Quasi-elastic (p,n) scattering data on 232 Th and 238 U to the isobaric analogue states of the target nucleus are also used to constrain the isovector part of the optical potential. For even-even (odd) 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.

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

Cited by 48 publications

References 36 publications

Optical model with multiple band couplings using soft rotator structure

Optical model with multiple band couplings using soft rotator structure

A dispersive optical model potential for nucleon induced reactions on²³⁸U and²³²Th nuclei with full coupling

A Lane consistent optical model potential for nucleon scattering on actinide nuclei with extended coupling

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

Cited by 48 publications

References 36 publications

Optical model with multiple band couplings using soft rotator structure

Optical model with multiple band couplings using soft rotator structure

A dispersive optical model potential for nucleon induced reactions on238U and232Th nuclei with full coupling

A Lane consistent optical model potential for nucleon scattering on actinide nuclei with extended coupling

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A dispersive optical model potential for nucleon induced reactions on²³⁸U and²³²Th nuclei with full coupling