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Nuclear Theory·nucl-th

Tuesday·July 5, 2016

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 01

    Electromagnetic effects on meson production: a new tool for studying the space-time evolution of heavy ion collisions

    Andrzej Rybicki🇵🇱 · Antoni Szczurek🇵🇱 · Mariola Klusek-Gawenda🇵🇱 · Nikolaos Davis · Vitalii Ozvenchuk🇵🇱 · Miroslaw Kielbowicz🇵🇱

    We review our studies of spectator-induced electromagnetic (EM) effects on the emission of charged mesons in the final state of ultrarelativistic heavy ion collisions. We argue that these effects offer sensitivity to the distance between the charged meson formation zone at freeze-out and the spectator system. As such, they can serve as an independent, new tool to probe the space-time and longitudinal evolution of the system created in the collision. As a phenomenological application for this tool in the context of resonance production and decay, we obtain a first estimate of the time of pion emission from EM effects. This we compare to existing HBT data.

    nucl-thnucl-exEPJ Web Conf.(2016)·4 citations
  2. 02

    Nucleon localization and fragment formation in nuclear fission

    C. L. Zhang · B. Schuetrumpf · W. Nazarewicz

    An electron localization measure was originally introduced to characterize chemical bond structures in molecules. Recently, a nucleon localization based on Hartree-Fock densities has been introduced to investigate -cluster structures in light nuclei. Compared to the local nucleonic densities, the nucleon localization function has been shown to be an excellent indicator of shell effects and cluster correlations. Using the spatial nucleon localization measure, we investigate the emergence of fragments in fissioning heavy nuclei. To illustrate basic concepts of nucleon localization, we employ the self-consistent energy density functional method with a quantified energy density functional optimized for fission studies. We study the particle densities and spatial nucleon localization distributions along the fission pathways of Fm, Th and Pu. We demonstrate that the fission fragments are formed fairly early in the evolution, well before scission. We illustrate the usefulness of the localization measure by showing how the hyperdeformed state of Th can be understood in terms of a quasimolecular state made of Sn and Zr fragments. Compared to nucleonic distributions, the nucleon localization function more effectively quantifies nucleonic clustering: its characteristic oscillating pattern, traced back to shell effects, is a clear fingerprint of cluster/fragment configurations. This is of particular interest for studies of fragment formation and fragment identification in fissioning nuclei.

    nucl-thPRC(2016)·63 citations
  3. 03

    Schematic Interactions with Many Degeneracies

    Arun Kingan · Michael Quinonez · Larry Zamick

    In previous works we examined the spectra for systems of 2 protons and 2 neutrons, in a single j shell calculation, by obtaining matrix elements from experiment. More recently we considered schematic interactions in the same model space. We continue in this vein here. The present work and the former can be regarded as 2 bookends on a bookshelf.

    nucl-thIJMPE(2017)·0 citations
  4. 04

    The nuclear quadrupole moment mesured with Nuclear Quadrupole Resonance NQR : Principle and definition

    Mohamed Belfkir

    The nuclear quadruple moment is a fundamental character associated to the nuclei, this moment is related to the not purely spherical distribution in the nuclei, indeed its measure allows us to survey the geometric deformation of the nuclei of its spherical shape. The measurement methods of the quadruple moment is to study the electrical energy hyperfine interaction between the quadruple moment and the electric field gradient due to atomics electrons, one of the methods is the nuclear quadruple resonance NQR which is observed at the transitions between energy levels splits by the effect of the quadruple interaction and induced by a radio frequency field.

    nucl-th0 citations
  5. 05

    Infinite matter properties and zero-range limit of nonrelativistic finite-range interactions

    D. Davesne🇫🇷 · P. Becker🇫🇷 · A. Pastore🇬🇧 · J. Navarro🇪🇸

    We discuss some infinite matter properties of two finite-range interactions widely used for nuclear structure calculations, namely Gogny and M3Y interactions. We show that some useful informations can be deduced for the central, tensor and spin-orbit terms from the spin-isospin channels and the partial wave decomposition of the symmetric nuclear matter equation of state. We show in particular that the central part of the Gogny interaction should benefit from the introduction of a third Gaussian and the tensor parameters of both interactions can be deduced from special combinations of partial waves. We also discuss the fact that the spin-orbit of the M3Y interaction is not compatible with local gauge invariance. Finally, we show that the zero-range limit of both families of interactions coincides with the specific form of the zero-range N3LO Skyrme interaction and we emphasize from this analogy the benefits of N3LO.

    nucl-thAnnals Phys.(2016)·21 citations
  6. 06

    Quasidynamical symmetries in the backbending of chromium isotopes

    Raul A. Herrera · Calvin W. Johnson

    Background: Symmetries are a powerful way to characterize nuclear wave functions. A true dynamical symmetry, where the Hamiltonian is block-diagonal in subspaces defined by the group, is rare. More likely is a quasidynamical symmetry: states with different quantum numbers (i.e. angular momentum) nonetheless sharing similar group-theoretical decompositions. Purpose: We use group-theoretical decomposition to investigate backbending, an abrupt change in the moment of inertia along the yrast line, in Cr: prior mean-field calculations of these nuclides suggest a change from strongly prolate to more spherical configurations as one crosses the backbending and increases in angular momentum. Methods: We decompose configuration-interaction shell-model wavefunctions using the SU(2) groups (total orbital angular momentum) and (total spin), and the groups SU(3) and SU(4). We do not need a special basis but only matrix elements of Casimir operators, applied with a modified Lanczos algorithm. Results: We find quasidynamical symmetries, albeit often of a different character above and below the backbending, for each group. While the strongest evolution was in SU(3), the decompositions did not suggest a decrease in deformation. We point out with a simple example that mean-field and SU(3) configurations may give very different pictures of deformation. Conclusions: Persistent quasidynamical symmetries for several groups allow us to identify the members of a band and to characterize how they evolve with increasing angular momentum, especially before and after backbending.

    nucl-thPRC(2017)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE