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Nuclear Theory·nucl-th

Tuesday·January 26, 2016

13 papers—6 primary·7 cross-listed

All13Primary6Cross-lists7
  1. 01

    Nuclear charge and neutron radii and nuclear matter: trend analysis

    P.-G. Reinhard · W. Nazarewicz

    Radii of charge and neutron distributions are fundamental nuclear properties. They depend on both nuclear interaction parameters related to the equation of state of infinite nuclear matter and on quantal shell effects, which are strongly impacted by the presence of nuclear surface. In this work, by studying the dependence of charge and neutron radii, and neutron skin, on nuclear matter parameters, we assess different mechanisms that drive nuclear sizes. We apply nuclear density functional theory using a family of Skyrme functionals obtained by means of different optimization protocols targeting specific nuclear properties. By performing the Monte-Carlo sampling of reasonable functionals around the optimal parametrization, we study correlations between nuclear matter paramaters and observables characterizing charge and neutron distributions. We demonstrate the existence of the strong converse relation between the nuclear charge radii and the saturation density of symmetric nuclear matter and also between the neutron skins and the slope of the symmetry energy. For functionals optimized to experimental binding energies only, proton and neutron radii are weakly correlated due to canceling trends from different nuclear matter parameters. We show that by requiring that the nuclear functional reproduces the empirical saturation point of symmetric nuclear matter practically fixes the charge (or proton) radii, and vice versa. The neutron skin uncertainty primarily depends on the slope of the symmetry energy. Consequently, imposing a constraint on both and practically determines the nuclear size, modulo small variations due to shell effects.

    nucl-thPRC(2016)·57 citations
  2. 02

    Exotic neutron-rich medium-mass nuclei with realistic nuclear forces

    Naofumi Tsunoda · Takaharu Otsuka · Noritaka Shimizu · Morten Hjorth-Jensen · Kazuo Takayanagi · Toshio Suzuki

    We present the first application of the newly developed EKK theory of the effective nucleon-nucleon interaction to shell-model studies of exotic nuclei, including those where conventional approaches with fitted interactions encounter difficulties. This EKK theory enables us to derive the interaction suitable for several major shells (+ in this work). By using such an effective interaction obtained from the Entem-Machleidt QCD-based interaction and the Fujita-Miyazawa three-body force, the energies, E2 properties and spectroscopic factors of low-lying states of neutron-rich Ne, Mg and Si isotopes are nicely described, as the first shell-model description of the "island of inversion" without fit of the interaction. The long-standing question as to how particle-hole excitations occur across the - magic gap is clarified with distinct differences from the conventional approaches. The shell evolution is shown to appear similarly to earlier studies.

    nucl-thPRC(2017)·91 citations
  3. 03

    Dynamical Coupling of Pygmy and Giant Resonances in Relativistic Coulomb Excitation

    N.S. Brady · T. Aumann · C.A. Bertulani · J.O. Thomas

    We study the Coulomb excitation of pygmy dipole resonances (PDR) in heavy ion reactions at 100 MeV/nucleon and above. The reactions 68Ni+197Au and 68Ni+208Pb are taken as a practical examples. Our goal is to address the question of the influence of giant resonances on the PDR as the dynamics of the collision evolves. We show that the coupling to the giant resonances affects considerably the excitation probabilities of the PDR, a result that indicates the need of an improved theoretical treatment of the reaction dynamics at these bombarding energies.

    nucl-thPLB(2016)·5 citations
  4. 04

    On Exotic Systems of Baryons in Chiral Soliton Models

    Vladimir Kopeliovich (INR, Moscow & NORDITA)🇷🇺

    The role of zero mode quantum corrections to the energy of baryonic systems with exotic quantum numbers (strangeness) is discussed. A simple expression for the contribution depending on strange inertia is obtained in the collective coordinate quantization approach, and it is shown that this correction stabilizes the systems the stronger the greater their baryon number is. Furthemore, systems are considered which could be interpreted in the quark model language as containing additional pairs. It is argued that a strange skyrmion crystal should have additional binding in comparison with the quantized neutron crystal.

    nucl-thhep-thPLB(1991)·36 citations
  5. 05

    Time-dependent Hartree-Fock calculations for multinucleon transfer and quasifission processes in the Ni+U reaction

    Kazuyuki Sekizawa · Kazuhiro Yabana

    Background: Multinucleon transfer (MNT) and quasifission (QF) processes are dominant processes in low-energy collisions of two heavy nuclei. They are expected to be useful to produce neutron-rich unstable nuclei. Nuclear dynamics leading to these processes depends sensitively on nuclear properties such as deformation and shell structure. Purpose: We elucidate reaction mechanisms of MNT and QF processes involving heavy deformed nuclei, making detailed comparisons between microscopic time-dependent Hartree-Fock (TDHF) calculations and measurements for the Ni+U reaction. Methods: Three-dimensional Skyrme-TDHF calculations are performed. Particle-number projection method is used to evaluate MNT cross sections from the TDHF wave function after collision. Results: Fragment masses, total kinetic energy (TKE), scattering angle, contact time, and MNT cross sections are investigated for the Ni+U reaction. They show reasonable agreements with measurements. At small impact parameters, collision dynamics depends sensitively on the orientation of deformed U. In tip (side) collisions, we find a larger (smaller) TKE and a shorter (longer) contact time. In tip collisions, we find a strong influence of quantum shells around Pb. Conclusions: It is confirmed that the TDHF calculations reasonably describe both MNT and QF processes in the Ni+U reaction. Analyses of this system indicates the significance of the nuclear structure effects such as deformation and quantum shells in nuclear reaction dynamics at low energies.

    nucl-thnucl-exPRC(2016)·146 citations
  6. 06

    Gamow shell model description of radiative capture reactions LiBe and LiLi

    G.X. Dong🇫🇷 · N. Michel🇫🇷 · K. Fossez🇺🇸 · M. Płoszajczak🇫🇷 · Y. Jaganathen🇺🇸 · R.M. Id Betan🇦🇷

    According to standard stellar evolution, lithium abundance is believed to be a useful indicator of the stellar age. However, many evolved stars like red giants show huge fluctuations around expected theoretical abundances that are not yet fully understood. The better knowledge of nuclear reactions that contribute to the creation and destruction of lithium can help to solve this puzzle. In this work we apply the Gamow shell model (GSM) formulated in the coupled-channel representation (GSM-CC) to investigate the mirror radiative capture reactions LiBe and LiLi. The cross-sections are calculated using a translationally invariant Hamiltonian with the finite-range interaction which is adjusted to reproduce spectra, binding energies and one-nucleon separation energies in Li, Be. All relevant , , and transitions from the initial continuum states to the final bound states and of Li and Be are included. We demonstrate that the -wave radiative capture of proton (neutron) to the first excited state of Be (Li) is crucial and increases the total astrophysical -factor by about 40 \%.

    nucl-thJ.Phys.G(2017)·37 citations

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first authorsco-authorsvia INSPIRE