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Nuclear Theory·nucl-th

Monday·November 30, 2015

10 papers—4 primary·6 cross-listed

All10Primary4Cross-lists6
  1. 01

    [Submitted on 26 Nov 2015]

    Influence of binding energies of electrons on nuclear mass predictions

    Jing Tang · Zhong-Ming Niu · Jian-You Guo

    Nuclear mass contains a wealth of nuclear structure information, and has been widely employed to extract the nuclear effective interactions. The known nuclear mass is usually extracted from the experimental atomic mass by subtracting the masses of electrons and adding the binding energy of electrons in the atom. However, the binding energies of electrons are sometimes neglected in extracting the known nuclear masses. The influence of binding energies of electrons on nuclear mass predictions are carefully investigated in this work. If the binding energies of electrons are directly subtracted from the theoretical mass predictions, the rms deviations of nuclear mass predictions with respect to the known data are increased by about keV for nuclei with . Furthermore, by using the Coulomb energies between protons to absorb the binding energies of electrons, their influence on the rms deviations is significantly reduced to only about keV for nuclei with . However, the binding energies of electrons are still important for the heavy nuclei, about keV for nuclei around and up to about keV for nuclei around . Therefore, it is necessary to consider the binding energies of electrons to reliably predict the masses of heavy nuclei at an accuracy of hundreds of keV.

    Comments:
    5 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1511.08273 [pdf]
    CPC(2016)·3 citations
  2. 02

    [Submitted on 26 Nov 2015]

    Multinucleon transfer reaction in time-dependent Hartree-Fock theory

    Kazuyuki Sekizawa · Kazuhiro Yabana

    Time-dependent Hartree-Fock (TDHF) theory has achieved a remarkable success in describing and understanding nuclear many-body dynamics from nucleons' degrees of freedom. We here report our investigation of multinucleon transfer (MNT) processes employing the TDHF theory. To calculate transfer probabilities for channels specified by the number of protons and neutrons included in reaction products, a particle-number projection (PNP) method has been developed. The PNP method is also used to calculate excitation energies of reaction products. Combined use of the PNP method with a statistical model, we can evaluate MNT cross sections taking account of effects of particle evaporation. Using these methods, we evaluate MNT cross sections for Ca+Sn, Ca+Pb, and Ni+Pb reactions. From systematic analyses, we find that cross sections for channels with a large reaction probability are in good agreement with experimental data. However, the agreement becomes less accurate as the number of transferred nucleons increases. Possible directions to improve the description are discussed.

    Comments:
    To be published in the ebook "Progress of time-dependent nuclear reaction theory" honoring Prof. Joachim Maruhn's retirement
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1511.08322 [pdf]
    4 citations
  3. 03

    [Submitted on 27 Nov 2015]

    Isovector and isoscalar dipole excitations in Be and Be studied with antisymmetrized molecular dynamics

    Yoshiko Kanada-En'yo

    Isovector and isoscalar dipole excitations in Be and Be are investigated in the framework of antisymmetrized molecular dynamics, in which angular-momentum and parity projections are performed. In the present method, 1p-1h excitations on the ground state and large amplitude -cluster mode are incorporated. The isovector giant dipole resonance (GDR) in MeV shows the two peak structure which is understood by the dipole excitation in the 2 core part with the prolate deformation. Because of valence neutron modes against the core, low-energy E1 resonances appear in MeV exhausting about of the Thomas-Reiche-Kuhn sum rule and of the calculated energy-weighted sum. The dipole resonance at MeV in Be can be interpreted as the parity partner of the ground state having a He+ structure and has the remarkable E1 strength because of coherent contribution of two valence neutrons. The ISD strength for some low-energy resonances are significantly enhanced by the coupling with the -cluster mode. The calculated E1 strength of Be reasonably describes the global feature of experimental photonuclear cross sections consisting of the low-energy strength in MeV and the GDR in MeV.

    Comments:
    17 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1511.08530 [pdf]
    PRC(2016)·26 citations
  4. 04

    [Submitted on 27 Nov 2015]

    Hybrid Stars using the Quark-Meson Coupling and Proper Time NJL Models

    D. L. Whittenbury🇦🇺 · H. H. Matevosyan🇦🇺 · A. W. Thomas🇦🇺

    Background: At high density deconfinement of hadronic matter may occur leading to quark matter. The immense densities reached in the inner core of massive neutron stars may be sufficient to facilitate the transition. Purpose: To investigate a crossover transition between two phenomenological models which epitomise QCD in two different regimes, while incorporating the influence of quark degrees of freedom in both. Method: We use the Hartree-Fock quark-meson coupling model and the proper time regularised three flavour NJL model to describe hadronic and quark matter, respectively. Hybrid equations of state are obtained by interpolating the energy density as a function of total baryonic density and calculating the pressure. Results: Equations of state for hadronic, quark and hybrid matter and the resulting mass versus radius curves for hybrid stars are shown, as well as other relevant physical quantities such as species fractions and the speed of sound in matter. Conclusions: The observations of massive neutron stars can certainly be explained within such a construction. However, the so-called thermodynamic correction arising from an interpolation method can have a considerable impact on the equation of state. The interpolation dependency of and physical meaning behind such corrections require further study.

    Comments:
    23 pages, 10 figures and 4 tables
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    1511.08561 [pdf]
    PRC(2016)·53 citations

Affiliations

first authorsco-authorsvia INSPIRE