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AbstractAbstract

[en] Interplay between the dependence of symmetry energy on density and the variation of nucleonic densities across nuclear surface is discussed. That interplay gives rise to the mass dependence of the symmetry coefficient in an energy formula. Charge symmetry of the nuclear interactions allows to introduce isoscalar and isovector densities that are approximately independent of the magnitude of neutron-proton asymmetry. (author)

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15. Nuclear Physics Workshop "Marie and Pierre Curie": 70 years of nuclear fission; Kazimierz Dolny (Poland); 24-28 Sep 2008; Available from DOI: http://dx.doi.org/10.1142/S0218301309013014

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International Journal of Modern Physics E; ISSN 0218-3013; ; v. 18(4); p. 892-899

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AbstractAbstract

[en] Energy in nuclear matter is, in practice, completely characterized at different densities and asymmetries, when the density dependencies of symmetry energy and of energy of symmetric matter are specified. The density dependence of the symmetry energy at subnormal densities produces mass dependence of nuclear symmetry coefficient and, thus, can be constrained by that latter dependence. We deduce values of the mass dependent symmetry coefficients, by using excitation energies to isobaric analog states. The coefficient systematic, for intermediate and high masses, is well described in terms of the symmetry coefficient values of a

_{a}^{V}= (31.5-33.5) MeV for the volume coefficient and a_{a}^{S}= (9-12) MeV for the surface coefficient. These two further correspond to the parameter values describing density dependence of symmetry energy, of L∼95 MeV and K_{sym}∼25 MeVPrimary Subject

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7. Latin American symposium on nuclear physics and applications; Cusco (Peru); 11-16 Jun 2007; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)

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AbstractAbstract

[en] In the present paper, we examine past measurements of ground state to ground state (d,p) and (p,d) transfers that were performed on targets with Z=3-24. We describe a procedure that we utilized to extract a consistent set of spectroscopic factors. Most of the 80 spectroscopic factors that we extracted are in good agreement with large-basis shell model predictions. We evaluate the consistency of this method by comparing the spectroscopic factors obtained separately in (p,d) and (d,p) reactions. For nuclei for which Endt has compiled values, our results and those of Endt are strongly correlated. We apply our method to more reactions and more nuclei than Endt had, and our comparisons between spectroscopic factors obtained in (d,p) and (p,d) reactions display more consistency than the corresponding comparisons in Endt

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(c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)

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AbstractAbstract

[en] We have extracted the ground state to ground state neutron spectroscopic factors for 80 nuclei ranging in Z from 3 to 24 by analyzing the past measurements of the angular distributions from (d,p) and (p,d) reactions. We demonstrate an approach that provides systematic and consistent values with a minimum of assumptions. A three-body model with global optical potentials and standard geometry of n-potential is applied. For the 60 nuclei where modern shell model calculations are available, such analysis reproduces, to within 20%, the experimental spectroscopic factors for most nuclei. If we constraint the nucleon-target optical potential and the geometries of the bound neutron-wave function with the modern Hartree-Fock calculations, our deduced neutron spectroscopic factors are reduced by 30% on average

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International symposium on exotic nuclei; Khanty-Mansiysk (Russian Federation); 17-22 Jul 2006; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)

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APPROXIMATIONS, BARYON REACTIONS, BARYONS, CALCULATION METHODS, CHARGED-PARTICLE REACTIONS, DIMENSIONLESS NUMBERS, DIRECT REACTIONS, DISTRIBUTION, ELEMENTARY PARTICLES, ENERGY LEVELS, FERMIONS, FUNCTIONS, HADRON REACTIONS, HADRONS, MANY-BODY PROBLEM, MATHEMATICAL MODELS, NUCLEAR MODELS, NUCLEAR REACTIONS, NUCLEON REACTIONS, NUCLEONS

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Danielewicz, Pawel; Lee, Jenny, E-mail: danielewicz@nscl.msu.edu, E-mail: jennylee@ribf.riken.jp

arXiv e-print [ PDF ]

arXiv e-print [ PDF ]

AbstractAbstract

[en] Using excitation energies to isobaric analog states (IAS) and charge invariance, we extract nuclear symmetry coefficients, representing a mass formula, on a nucleus-by-nucleus basis. Consistently with charge invariance, the coefficients vary weakly across an isobaric chain. However, they change strongly with nuclear mass and range from a

_{a}∼10 MeV at mass A∼10 to a_{a}∼22 MeV at A∼240. Variation with mass can be understood in terms of dependence of nuclear symmetry energy on density and the rise in importance of low densities within nuclear surface in smaller systems. At A≳30, the dependence of coefficients on mass can be well described in terms of a macroscopic volume–surface competition formula with a_{a}^{V}≃33.2 MeV and a_{a}^{S}≃10.7 MeV. Our further investigation shows, though, that the fitted surface symmetry coefficient likely significantly underestimates that for the limit of half-infinite matter. Following the considerations of a Hohenberg–Kohn functional for nuclear systems, we determine how to find in practice the symmetry coefficient using neutron and proton densities, even when those densities are simultaneously affected by significant symmetry-energy and Coulomb effects. These results facilitate extracting the symmetry coefficients from Skyrme–Hartree–Fock (SHF) calculations, that we carry out using a variety of Skyrme parametrizations in the literature. For the parametrizations, we catalog novel short-wavelength instabilities. In our further analysis, we retain only those parametrizations which yield systems that are adequately stable both in the long- and short-wavelength limits. In comparing the SHF and IAS results for the symmetry coefficients, we arrive at narrow (±2.4 MeV) constraints on the symmetry-energy values S(ρ) at 0.04≲ρ≲0.13 fm^{−3}. Towards normal density the constraints significantly widen, but the normal value of energy a_{a}^{V}and the slope parameter L are found to be strongly correlated. To narrow the constraints, we reach for the measurements of asymmetry skins and arrive at a_{a}^{V}=30.2–33.7 MeV and L=35–70 MeV, with those values being again strongly positively correlated along the diagonal of their combined region. Inclusion of the skin constraints allows to narrow the constraints on S(ρ), at 0.04≲ρ≲0.13 fm^{−3}, down to ±1.1 MeV. Several microscopic calculations, including variational, Bruckner–Hartree–Fock and Dirac–Bruckner–Hartree–Fock, are consistent with our constraint region on S(ρ)Primary Subject

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S0375-9474(13)00787-2; Available from http://dx.doi.org/10.1016/j.nuclphysa.2013.11.005; Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)

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AbstractAbstract

[en] The ground state neutron spectroscopic factors for 80 nuclei ranging in Z from 3 to 24 have been extracted by analyzing the past measurements of the angular distributions from (d,p) and (p,d) reactions. We demonstrate an approach that provides systematic and consistent values with minimum assumptions. For the 61 nuclei that have been described by large-basis shell-model calculations, most experimental spectroscopic factors are reproduced to within 20%

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(c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)

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ANGULAR DISTRIBUTION, BERYLLIUM ISOTOPES, BORON ISOTOPES, CARBON ISOTOPES, CHROMIUM ISOTOPES, DEUTERON REACTIONS, DEUTERONS, GROUND STATES, LITHIUM ISOTOPES, NEUTRON SPECTROSCOPY, NEUTRONS, PROTON REACTIONS, PROTON-NUCLEON INTERACTIONS, PROTONS, SHELL MODELS, SPECTROSCOPIC FACTORS, TITANIUM ISOTOPES, VANADIUM ISOTOPES

ALKALINE EARTH ISOTOPES, BARYON REACTIONS, BARYON-BARYON INTERACTIONS, BARYONS, CHARGED PARTICLES, CHARGED-PARTICLE REACTIONS, DIMENSIONLESS NUMBERS, DISTRIBUTION, ELEMENTARY PARTICLES, ENERGY LEVELS, FERMIONS, HADRON REACTIONS, HADRON-HADRON INTERACTIONS, HADRONS, INTERACTIONS, ISOTOPES, MATHEMATICAL MODELS, NUCLEAR MODELS, NUCLEAR REACTIONS, NUCLEON REACTIONS, NUCLEON-NUCLEON INTERACTIONS, NUCLEONS, PARTICLE INTERACTIONS, SPECTROSCOPY

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AbstractAbstract

[en] 177 neutron spectroscopic factors for nickel isotopes have been extracted by performing a systematic analysis of the angular distributions measured from (d,p) transfer reactions. A subset of the extracted spectroscopic factors are compared to predictions of large-basis shell models in the full pf model space using the GXPF1A effective interaction, and the (f

_{5/2},p_{3/2},p_{1/2},g_{9/2}) model space using the JJ4PNA interaction. For ground states, the predicted spectroscopic factors using the GXPF1A effective interaction in the full pf model space agree very well with the experimental values, while predictions based on several other effective interactions and model spaces are about 30% higher than the experimental values. For low-energy excited states (<3.5 MeV), the agreement between the extracted spectroscopic factors and shell model calculations is not better than a factor of two.Primary Subject

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(c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)

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Danielewicz, Pawel; Lee, Jenny, E-mail: danielewicz@nscl.msu.edu, E-mail: lee@nscl.msu.edu

arXiv e-print [ PDF ]

arXiv e-print [ PDF ]

AbstractAbstract

[en] Energy for a nucleus is considered in the macroscopic limit, in terms of nucleon numbers. Further considered for a nuclear system is the Hohenberg-Kohn energy functional, in terms of proton and neutron densities. Finally, Skyrme-Hartree-Fock calculations are carried out for a half-infinite particle-stable nuclear-matter. In each case, the attention is focused on the role of neutron-proton asymmetry and on the nuclear symmetry energy. We extend the considerations on the symmetry term from an energy formula to the respective term within the Hohenberg-Kohn functional. We show, in particular, that in the limit of an analytic functional, and subject to possible Coulomb corrections, it is possible to construct isoscalar and isovector densities out of the proton and neutron densities, that retain a universal relation to each other, approximately independent of asymmetry. In the so-called local approximation, the isovector density is inversely proportional to the symmetry energy in uniform matter, at the local isoscalar density. Generalized symmetry coefficient of a nuclear system is related, in the analytic limit of the functional, to an integral of the isovector density. We test the relations, inferred from the Hohenberg-Kohn functional, in the Skyrme-Hartree-Fock calculations of half-infinite matter. Within the calculations, we obtain surface symmetry coefficients and parameters characterizing the densities, for the majority of Skyrme parameterizations proposed in the literature. The volume-to-surface symmetry-coefficient ratio, and the displacement of nuclear isovector relative to isoscalar surfaces, both strongly increase as the slope of symmetry energy, in the vicinity of normal density, increases

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S0375-9474(08)00792-6; Available from http://dx.doi.org/10.1016/j.nuclphysa.2008.11.007; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)

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AbstractAbstract

[en] We carry out a systematic analysis of angular distribution measurements for selected ground-state to ground-state (d,p) and (p,d) neutron transfer reactions, including the calcium isotopes. We propose a consistent three-body model reaction methodology in which we constrain the transferred-neutron bound state and nucleon-target optical potential geometries using modern Hartree-Fock calculations. Our deduced neutron spectroscopic factors are found to be suppressed by ∼30% relative to independent-particle shell-model values, from

^{40}Ca through^{49}Ca. The other nuclei studied, ranging from B to Ti, show similar average suppressions with respect to large-basis shell-model expectations. Our results are consistent with deduced spectroscopic strengths for neutrons and protons from intermediate-energy nucleon knockout reactions and for protons from (e,e^{'}p) reactions on well-bound nucleiPrimary Subject

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(c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)

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ANGULAR DISTRIBUTION, BOUND STATE, CALCIUM 40, CALCIUM 49, DEUTERON REACTIONS, ELECTRON REACTIONS, ELECTRONS, GEOMETRY, GROUND STATES, HARTREE-FOCK METHOD, KNOCK-OUT REACTIONS, NEUTRON TRANSFER, OPTICAL MODELS, POTENTIALS, PROTON-NUCLEON INTERACTIONS, PROTONS, SHELL MODELS, SPECTROSCOPIC FACTORS, THREE-BODY PROBLEM, TRANSFER REACTIONS

ALKALINE EARTH ISOTOPES, APPROXIMATIONS, BARYON-BARYON INTERACTIONS, BARYONS, BETA DECAY RADIOISOTOPES, BETA-MINUS DECAY RADIOISOTOPES, CALCIUM ISOTOPES, CALCULATION METHODS, CHARGED-PARTICLE REACTIONS, DIMENSIONLESS NUMBERS, DIRECT REACTIONS, DISTRIBUTION, ELEMENTARY PARTICLES, ENERGY LEVELS, EVEN-EVEN NUCLEI, EVEN-ODD NUCLEI, FERMIONS, HADRON-HADRON INTERACTIONS, HADRONS, INTERACTIONS, INTERMEDIATE MASS NUCLEI, ISOTOPES, LEPTON REACTIONS, LEPTONS, LIGHT NUCLEI, MANY-BODY PROBLEM, MATHEMATICAL MODELS, MATHEMATICS, MINUTES LIVING RADIOISOTOPES, NUCLEAR MODELS, NUCLEAR REACTIONS, NUCLEI, NUCLEON-NUCLEON INTERACTIONS, NUCLEONS, PARTICLE INTERACTIONS, RADIOISOTOPES, STABLE ISOTOPES

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AbstractAbstract

[en] We have extracted 565 neutron spectroscopic factors of sd and fp shell nuclei by systematically analyzing more than 2000 measured (d, p) angular distributions. We are able to compare 125 of the extracted spectroscopic factors to values predicted by large-basis shell-model calculations and evaluate the accuracies of spectroscopic factors predicted by different shell-model interactions in these regions. We find that the spectroscopic factors predicted for most excited states of sd-shell nuclei using the latest USDA or USDB interactions agree with the experimental values. For fp shell nuclei, the inability of the current models to account for the core excitation and fragmentation of the states leads to considerable discrepancies. In particular, the agreement between data and shell-model predictions for Ni isotopes is not better than a factor of 2 using either the GXPF1A or the XT interaction

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(c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)

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