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Nuclear Theory·nucl-th

Tuesday·June 27, 2017

8 papers—6 primary·2 cross-listed

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  1. 01

    [Submitted on 25 Jun 2017]

    meson transparency in nuclei from resonant interactions

    D. Cabrera🇪🇸 · A. N. Hiller Blin🇪🇸 · M. J. Vicente Vacas🇪🇸 · P. Fernandez de Cordoba🇪🇸

    We investigate the meson nuclear transparency using some recent theoretical developments on the in medium self-energy. The inclusion of direct resonant -scattering and the kaon decay mechanisms leads to a width much larger than in most previous theoretical approaches. The model has been confronted with photoproduction data from CLAS and LEPS and the recent proton induced production from COSY finding an overall good agreement. The results support the need of a quite large direct -scattering contribution to the self-energy.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1706.08064 [pdf]
    PRC(2017)·25 citations
  2. 02

    [Submitted on 25 Jun 2017]

    Predicting the optical observables for nucleon scattering on even-even actinides

    D. S. Martyanov🇧🇾 · E. Sh. Soukhovitskii🇧🇾 · R. Capote🇦🇹 · J. M. Quesada🇪🇸 · S. Chiba🇯🇵

    Previously derived Lane consistent dispersive coupled-channel optical model for nucleon scattering on Th and U nuclei is extended to describe scattering on even-even actinides with 90--98. A soft-rotator-model (SRM) description of the low-lying nuclear structure is used, where SRM Hamiltonian parameters are adjusted to the observed collective levels of the target nucleus. SRM nuclear wave functions (mixed in quantum number) have been used to calculate coupling matrix elements of the generalized optical model. The "effective" deformations that define inter-band couplings are derived from SRM Hamiltonian parameters. Conservation of nuclear volume is enforced by introducing a dynamic monopolar term to the deformed potential leading to additional couplings between rotational bands. Fitted static deformation parameters are in very good agreement with those derived by Wang and collaborators using the Weizsäcker-Skyrme global mass model (WS4), allowing to use the latter to predict cross section for nuclei without experimental data. A good description of scarce "optical" experimental database is achieved. SRM couplings and volume conservation allow a precise calculation of the compound-nucleus formation cross sections, which is significantly different from the one calculated with rigid-rotor potentials coupling the ground-state rotational band. Derived parameters can be used to describe both neutron and proton induced reactions.

    Comments:
    6 pages, 4 figures, 5 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1706.08081 [pdf]
    CPC(2017)·3 citations
  3. 03

    [Submitted on 25 Jun 2017]

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

    E. Sh. Soukhovitskii · R. Capote · J. M. Quesada · S. Chiba · D. S. Martyanov

    Tamura coupling model 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- targets) including both axial and non-axial 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 multi-band transitions in even-even and odd- 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 Th, U and Pu nuclei and quasi-elastic (,) scattering data on Th and U. Lane consistent OMP is derived for all actinides if corresponding multi-band coupling schemes are defined. 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 150MeV. Multi-band coupling is stronger in even-even targets due 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. Coupling of ground-state rotational band levels in odd- nuclei is sufficient for a good description of the compound-nucleus formation cross sections as long as the coupling is saturated (a minimum of 7 coupled levels are typically needed).

    Comments:
    30 pages, 4 figures, 8 tables, 3 appendices
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1706.08086 [pdf]
    PRC(2016)·27 citations
  4. 04

    [Submitted on 25 Jun 2017]

    Deformed shell model study of event rates for WIMP- Ge scattering

    R. Sahu🇮🇳 · V.K.B. Kota🇮🇳

    The event detection rates for the WIMP (a dark matter candidate) are calculated with Ge as the detector. The calculations are performed within the deformed shell model (DSM) based on Hartree-Fock states. First the energy levels and magnetic moment for the ground state and two low lying positive parity states for this nucleus are calculated and compared with experiment. The agreement is quite satisfactory. Then the nuclear wave functions are used to investigate the elastic and inelastic scattering of WIMP from Ge. The nuclear structure factors which are independent of supersymmetric model are also calculated as a function of WIMP mass. The event rates are calculated for a given set of SUSY parameters. The calculation shows that Ge is a good detector for detecting dark matter.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1706.08112 [pdf]
    Mod.Phys.Lett.A(2017)·7 citations
  5. 05

    [Submitted on 26 Jun 2017]

    Deuteron: properties and analytical forms of wave function in coordinate space

    V. I. Zhaba🇺🇦

    Static parameters of the deuteron, obtained by the wave functions for various potential models, have been chronologically systematized. The presence or absence of knots near the origin of coordinates for the radial wave function of the deuteron have been shown. Analytical forms for the deuteron wave function in coordinate space have been reviewed. Both analytical forms and parameterizations of the deuteron wave function, which are necessary for further calculations of the characteristics of the processes involving the deuteron, have been provided. In addition, the asymptotic behaviors of deuteron wave function near the origin of coordinates and for large values of distance have been analyzed in the paper. Minimization of the number of numerically calculated coefficients for new analytical forms as a product of exponential function r^n by the sum of the exponential terms Ai*exp(-ai*r^3) have been done. The optimum is N=7-10.

    Comments:
    43 pages, 5 figures, 12 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1706.08306 [pdf]
    25 citations
  6. 06

    [Submitted on 26 Jun 2017]

    Formation of exotic baryon clusters in ultra-relativistic heavy-ion collisions

    A.S.Botvina (Frankfurt U., FIAS, ITP & Moscow, INR)🇩🇪 · J.Steinheimer (Frankfurt U., FIAS)🇩🇪 · M.Bleicher (Frankfurt U., FIAS, ITP & Juelich FZJ, NIC, JSC)🇩🇪

    Recent experiments at RHIC and LHC have demonstrated that there are excellent opportunities to produce light baryonic clusters of exotic matter (strange and anti-matter) in ultra-relativistic ion collisions. Within the hybrid-transport model UrQMD we show that the coalescence mechanism can naturally explain the production of these clusters in the ALICE experiment at LHC. As a consequence of this mechanism we predict the rapidity domains where the yields of such clusters are much larger than the observed one at midrapidity. This new phenomenon can lead to unique methods for producing exotic nuclei.

    Comments:
    15 pages, 4 figures, to be published in Phys. Rev. C
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1706.08335 [pdf]
    PRC(2017)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE