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Nuclear Theory·nucl-th

Friday·March 18, 2016

7 papers—3 primary·4 cross-listed

All7Primary3Cross-lists4
  1. 01

    [Submitted on 17 Mar 2016]

    Calculation of phases of np- scattering for potentials Reid93 and Argonne v18 on the phase-function method

    V. I. Zhaba

    A known phase-functions method has been considered for calculation of a single-channel nucleon-nucleon scattering. The phase shifts of np- scattering turn out for modern realistic phenomenological nucleon-nucleon potentials Reid93 but Argonne v18. Influence of choice of numeral method is explored on the decision of phase equation. For the decision of phase equation as differential equation of 1th order numeral methods are used: Euler method and Runge-Kutta methods 2-, 3-, 4- and 5th orders of exactness. Numerically calculated phase shifts of np- scattering for potentials Reid93 and Argonne v18 are in good agreement with the results obtained with the other methods of original works. Based on the known phases of scattering one can obtain the full amplitude, the full cross-section and the partial scattering amplitude accordingly. The used Runge-Kutta methods can be applied for finding of phases shifts of the mixed channels of nucleon-nucleon scattering.

    Comments:
    9 pages, 2 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1603.05382 [pdf]
    1 citation
  2. 02

    [Submitted on 17 Mar 2016]

    On the role of secondary pions in spallation targets

    Davide Mancusi🇫🇷 · Sergio Lo Meo🇮🇹 · Nicola Colonna🇮🇹 · Alain Boudard🇫🇷 · Miguel Antonio Cortés-Giraldo🇪🇸 · Joseph Cugnon🇧🇪 · Jean-Christophe David🇫🇷 · Sylvie Leray🇫🇷 · Jorge Lerendegui-Marco🇪🇸 · Cristian Massimi🇮🇹 · Vasilis Vlachoudis🇨🇭

    We use particle-transport simulations to show that secondary pions play a crucial role for the development of the hadronic cascade and therefore for the production of neutrons and photons from thick spallation targets. In particular, for the n_TOF lead spallation target, irradiated with 20 GeV/c protons, neutral pions are involved in the production of ~90% of the high-energy photons; charged pions participate in ~40% of the integral neutron yield. Nevertheless, photon and neutron yields are shown to be relatively insensitive to large changes of the average pion multiplicity in the individual spallation reactions. We characterize this robustness as a peculiar property of hadronic cascades in thick targets.

    Comments:
    17 pages, 14 figures. Submitted to Eur. Phys. J. A
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1603.05453 [pdf]
    EPJA(2017)·19 citations
  3. 03

    [Submitted on 17 Mar 2016]

    Single-particle spectral function of the hyperon in finite nuclei

    Isaac Vidana🇵🇹

    The spectral function of the hyperon in finite nuclei is calculated from the corresponding self-energy, which is constructed within a perturbative many-body approach using some of the hyperon-nucleon interactions of the Jülich and Nijmegen groups. Binding energies, wave functions and disoccupation numbers of different single-particle states are obtained for various hypernuclei from He to Pb. The agreement between the calculated binding energies and experimental data is qualitatively good. The small spin-orbit splitting of the and wave states is confirmed. The discrete and the continuum contributions of the single- spectral function are computed. Their appearance is qualitatively similar to that of the nucleons. The -factor, that measures the importance of correlations, is also calculated. Our results show that its value is relatively large, indicating that the hyperon is less correlated than nucleons. This is in agreement with the results obtained by other authors for the correlations of the in infinite nuclear matter. The disoccupation numbers are obtained by integrating the spectral function over the energy. Our results show that the discrete contribution to the disoccupation number decreases when increasing the momentum of the . This indicates that, in the production reactions of hypernuclei, the hyperon is mostly formed in a quasi-free state.

    Comments:
    27 pages, 9 figures, 4 tables. Corrected version accepted for publication in Nuclear Physics A
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1603.05635 [pdf]
    NPA(2017)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE