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Nuclear Theory·nucl-th

Tuesday·November 10, 2015

13 papers—6 primary·7 cross-listed

All13Primary6Cross-lists7
  1. 01

    [Submitted on 9 Nov 2015]

    Nuclear isospin asymmetry in decays of heavy nuclei

    Eunkyoung Shin · Yeunhwan Lim · Chang Ho Hyun · Yongseok Oh

    The effects of nuclear isospin asymmetry on decay lifetimes of heavy nuclei are investigated within various phenomenological models of nuclear potential for the particle. We consider the widely used simple square well potential and Woods-Saxon potential, and modify them by including an isospin asymmetry term. We then suggest a model for the potential of the particle motivated by a microscopic phenomenological approach of the Skyrme force model, which naturally introduce the isospin dependent form of the nuclear potential for the particle. The empirical decay lifetime formula of Viola and Seaborg is also modified to include isospin asymmetry effects. The obtained decay half-lives are in good agreement with the experimental data and we find that including the nuclear isospin effects somehow improves the theoretical results for decay half-lives. The implications of these results are discussed and the predictions on the decay lifetimes of superheavy elements are also presented.

    Comments:
    14 pages, 7 figures, 7 tables, Accepted by PRC 94, 024320 (2016)
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1511.02555 [pdf]
    PRC(2016)·45 citations
  2. 02

    [Submitted on 9 Nov 2015]

    Observables and initial conditions for rotating and expanding fireballs with spheroidal symmetry

    T. Csorgo🇭🇺 · M.I. Nagy🇭🇺 · I. F. Barna🇭🇺

    Utilizing a recently found class of exact, analytic rotating solutions of non-relativistic fireball hydrodynamics, we calculate analytically the single-particle spectra, the elliptic flows and two-particle Bose-Einstein correlation functions for rotating and expanding fireballs with spheroidal symmetry. We demonstrate, that rotation generates final state momentum anisotropies even for a spatially symmetric, spherical initial geometry of the fireball. The mass dependence of the effective temperatures, as well as the HBT radius parameters and the elliptic flow are shown to be sensitive not only to radial flow effects but also to the magnitude of the initial angular momentum.

    Comments:
    26 pages, with 18 .eps figures. Dedicated to L. P. Csernai on the occasion of his 65th birthday. Invited talk of T. Csörgő at the International Workshop on Collectivity in Relativistic Heavy Ion Collisions, Kolymbari, Crete,Greece, 14-20 September 2014, I.F. Barna at WPCF 2014, Gyöngyös, Hungary, 25-29 August 2014, and M. I. Nagy at WPCF 2015, Warsaw, Poland, 3-7 November 2015
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1511.02593 [pdf]
    PRC(2016)·12 citations
  3. 03

    [Submitted on 9 Nov 2015]

    Correlations between the fragmentation modes and light charged particles emission in heavy ion collisions

    Yingxun Zhang · Chengshuang Zhou · Jixian Chen · Ning Wang · Kai Zhao · Zhuxia Li

    The correlations between the shape of rapidity distribution of the yield of light charged particles and the fragmentation modes in semi-peripheral collisions for Zn+Zn, Zn+Zn and Ni+Ni at the beam energy of 35MeV/nucleon are investigated based on ImQMD05 code. Our studies show there is an interplay between the binary, ternary and multi-fragmentation break-up modes. The binary and ternary break-up modes more prefer to emit light charged particles at middle rapidity and give larger values of compared with the multi-fragmentation break-up mode does. The reduced rapidity distribution for the normalized yields of p, d, t, He, He and He and the corresponding values of can be used to estimate the probability of multi-fragmentation break-up modes. By comparing to experimental data, our results illustrate that 40\% of the collisions events belong to the multi-fragmentation break-up mode for the reactions we studied.

    Comments:
    15 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1511.02608 [pdf]
    SCPMA(2015)·8 citations
  4. 04

    [Submitted on 9 Nov 2015]

    Production of hypertritons in heavy ion collisions around the threshold of strangeness production

    Christoph Hartnack🇫🇷 · Arnaud Le Fèvre🇩🇪 · Yvonne Leifels🇩🇪 · Jörg Aichelin🇫🇷

    We use the Isospin Quantum Molecular Dynamics approach supplemented with a phase space coalescence to study the properties of the production of hypertritons. We see strong influences of the hyperon rescattering on the yields. The hypertritons show up to be quite aligned to the properties of nuclear matter underlining the necessity of rescattering to transport the hyperons to the spectator matter.

    Comments:
    8 pages, proceedings of 14th International Conference on Nuclear Reaction Mechanisms, Varenna (Italy), 2015
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1511.02646 [pdf]
    4 citations
  5. 05

    [Submitted on 9 Nov 2015]

    Ground and excited states of doubly open-shell nuclei from ab initio valence-space Hamiltonians

    S. R. Stroberg🇨🇦 · H. Hergert🇺🇸 · J. D. Holt🇨🇦 · S. K. Bogner🇺🇸 · A. Schwenk🇩🇪

    We present ab initio predictions for ground and excited states of doubly open-shell fluorine and neon isotopes based on chiral two- and three-nucleon interactions. We use the in-medium similarity renormalization group, in both flow-equation and Magnus formulations, to derive mass-dependent sd valence-space Hamiltonians. The experimental ground-state energies are reproduced through neutron number N=14, beyond which a new targeted normal-ordering procedure improves agreement with data and large-scale multi-reference calculations. For spectroscopy, we focus on neutron-rich 23-26F and 24-26Ne isotopes near N=14,16 magic numbers. In all cases we find an agreement with experiment competitive with established phenomenology. Moreover, yrast states are well described in 20Ne and 24Mg, providing an ab initio description of deformation in the medium-mass region.

    Comments:
    6 pages, 4 figures, published version
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1511.02802 [pdf]
    PRC(2016)·145 citations
  6. 06

    [Submitted on 9 Nov 2015]

    Approximate restoration of translational and rotational symmetries within the Lipkin method

    Y. Gao · J. Dobaczewski · P. Toivanen

    Background: Nuclear self-consistent mean-field approaches are rooted in the density functional theory and, through the spontaneous symmetry breaking mechanism, allow for including important correlations, while keeping the simplicity of the approach. Because real ground states should have all symmetries of the nuclear Hamiltonian, these methods require subsequent symmetry restoration. Purpose: We implement and study Lipkin method of approximate variation after projection applied to the restoration of the translational or rotational symmetries. Methods: We use Lipkin operators up to quadratic terms in momenta or angular momenta with self-consistently determined values of the Peierls-Yoccoz translational masses or moments of inertia, respectively. Calculations based on Skyrme energy-density functional are performed for heavy, deformed, and paired nuclei. Results: In deformed nuclei, the Peierls-Yoccoz translational masses along three different principal-axes directions of the intrinsic system can be different, which illustrates different widths of the total-momentum distributions. Numerically, the differences are only of the order of a few per cent. For the rotational-symmetry restoration, the Lipkin method compares favorably with the exact angular-momentum projection, which requires much larger computational effort. Conclusions: The Lipkin method of translational and rotational symmetry restoration is a practical low-cost method of determining the corresponding correlation energies. It allows for a simultaneous restoration of several symmetries and can be relatively easily implemented in the standard self-consistent mean-field calculations, including those required for the parameter adjustments.

    Comments:
    7 pages, 10 figures, version submitted to Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1511.02814 [pdf]
    1 citation

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first authorsco-authorsvia INSPIRE