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Nuclear Theory·nucl-th

Monday·September 10, 2018

10 papers—4 primary·6 cross-listed

All10Primary4Cross-lists6
  1. 01

    [Submitted on 6 Sept 2018]

    Splitting of single-particle levels in clusters potentials

    A.H. Santana-Valdés · R. Bijker

    In analogy with the Nilsson model, we calculate the splitting of spherical single-particle levels in a deformed field, but for cluster potentials. We study applications to alpha-cluster nuclei with two, three and four alpha particles, in which the deformation corresponds to the relative distance between the alpha particles. The splitting of the single-particle levels is studied for the cases of a dumbbell, equilateral triangle and a regular tetrahedron. The observed patterns may be used to gain insight into how the single-particle levels evolve with deformation.

    Comments:
    6 pages, 5 figures, 1 table, Proceedings XLI Symposium on Nuclear Physics, Cocoyoc, Mexico, 2018
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1809.02204 [pdf]
    J.Phys.Conf.Ser.(2018)·1 citation
  2. 02

    [Submitted on 6 Sept 2018]

    Excitation spectra of exotic nuclei in a self-consistent phonon-coupling model

    N. Lyutorovich · V. Tselyaev · J. Speth · P.-G. Reinhard

    We explore giant resonance spectra and low-lying dipole strength in the Ni and Sn chains from proton rich to very neutron rich isotopes, relevant in astrophysical reaction chains. For the theoretical description we employ the random-phase approximation (RPA) plus many-body effects through a phonon coupling model with optimized selection of phonons. The nuclear force is based on the Skyrme-Hartree-Fock energy functional carried consistently through all steps of modelling. The main effect of phonon coupling is a broadening of the spectral distributions (collisional width). This broadening is particularly dramatic for low-lying dipole strength in very neutron rich nuclei delivering there a qualitative change of the spectra.

    Comments:
    14 pages, 19 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1809.02247 [pdf]
    PRC(2018)·12 citations
  3. 03

    [Submitted on 7 Sept 2018]

    Nascent fragment shell effects on the nuclear fission processes in semiclassical periodic orbit theory

    Ken-ichiro Arita · Takatoshi Ichikawa · Kenichi Matsuyanagi

    Making use of the semiclassical periodic orbit theory (POT), we propose, for the first time, a method to exclusively evaluate the shell effects associated with each of the nascent fragments (prefragments) generated by the neck formation in nuclear fission processes. In spite of the strong indication of such shell effects in asymmetric fragment mass distributions, they could not have been accessed by any previous theoretical approach since most of the single-particle wave functions are delocalized. In the POT, we have found that the prefragment shell effects can be naturally and unambiguously identified as the ontributions of the classical periodic orbits localized in each of the prefragments. For a numerical test, simple cavity potential models are employed with the shape described by the three-quadratic-surface shape parametrization. Deformed shell energies are studied with the trace formula for degenerate orbits in a runcated spherical cavity which was recently derived [K. Arita, Phys. Rev. C 98, 064310 (2018)]. In this simple model, it is shown that the prefragment shell effect dominates the total shell energy shortly after the neck formation, and the magicity of the heavier prefragment plays a significant role in establishing the fission saddle with asymmetric shape which leads to an asymmetric scission.

    Comments:
    12 pages, 13 figures, published version
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1809.02320 [pdf]
    PRC(2018)·8 citations
  4. 04

    [Submitted on 7 Sept 2018]

    Interplaying mechanisms behind single inclusive jet suppression in heavy-ion collisions

    Yayun He (CCNU, LBNL)🇨🇳 · Shanshan Cao (WSU)🇺🇸 · Wei Chen (CCNU)🇨🇳 · Tan Luo (CCNU)🇨🇳 · Long-Gang Pang (UCB, LBNL)🇺🇸 · Xin-Nian Wang (CCNU, LBNL, UCB)🇨🇳

    The suppression factor for single inclusive jets in Pb+Pb collisions at the Large Hadron Collider (LHC) has a weak dependence on the transverse momentum and remains almost the same at two colliding energies, and 5.02 TeV, though the central rapidity density of bulk hadrons increases by about 20\%. This phenomenon is investigated within the Linear Boltzmann Transport (LBT) model, which includes elastic and inelastic processes based on perturbative QCD for both jet shower and recoil medium partons as they propagate through a quark-gluon plasma (QGP). With the dynamic evolution of the QGP given by the 3+1D CLVisc hydrodynamic model with event-by-event fully fluctuating initial conditions, single inclusive jet suppression in Pb+Pb collisions from LBT agrees well with experimental data. The weak and -dependence of the jet suppression factor at LHC are found to result directly from the -dependence of the initial jet spectra and slow -dependence of the jet energy loss. Contributions from jet-induced medium response, influence of radial expansion, both of which depend on jet-cone size, and jet flavor composition all conjoin to give a slow -dependence of jet energy loss and the single jet suppression factor , their dependence on and jet-cone size. Single inclusive jet suppression at GeV is also predicted that actually decreases slightly with in the GeV/ range because of the steeper initial jet spectra though the -dependence of the jet energy loss is weaker than that at LHC.

    Comments:
    22 pages in ReVTeX with 29 figures, final version to appear in PRC
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1809.02525 [pdf]
    PRC(2019)·133 citations

Affiliations

first authorsco-authorsvia INSPIRE