PaperPanorama
FAQ

Nuclear Theory·nucl-th

Monday·February 1, 2016

6 papers—5 primary·1 cross-listed

All6Primary5Cross-lists1
  1. 01

    [Submitted on 29 Jan 2016]

    Improving PWR core simulations by Monte Carlo uncertainty analysis and Bayesian inference

    Emilio Castro · Carolina Ahnert · Oliver Buss · Nuria Garcia-Herranz · Axel Hoefer · Dieter Porsch

    A Monte Carlo-based Bayesian inference model is applied to the prediction of reactor operation parameters of a PWR nuclear power plant. In this non-perturbative framework, high-dimensional covariance information describing the uncertainty of microscopic nuclear data is combined with measured reactor operation data in order to provide statistically sound, well founded uncertainty estimates of integral parameters, such as the boron letdown curve and the burnup-dependent reactor power distribution. The performance of this methodology is assessed in a blind test approach, where we use measurements of a given reactor cycle to improve the prediction of the subsequent cycle. As it turns out, the resulting improvement of the prediction quality is impressive. In particular, the prediction uncertainty of the boron letdown curve, which is of utmost importance for the planning of the reactor cycle length, can be reduced by one order of magnitude by including the boron concentration measurement information of the previous cycle in the analysis. Additionally, we present first results of non-perturbative nuclear-data updating and show that predictions obtained with the updated libraries are consistent with those induced by Bayesian inference applied directly to the integral observables.

    Comments:
    10 pages, 11 figures
    Subjects:
    Nuclear Theory (nucl-th); Instrumentation and Detectors (physics.ins-det)
    arXiv:
    1601.08036 [pdf]
    Annals Nucl.Energy(2016)·2 citations
  2. 02

    [Submitted on 29 Jan 2016]

    Finite Nuclei in the Quark-Meson Coupling (QMC) Model

    J. R. Stone🇬🇧 · P. A. M. Guichon🇫🇷 · P. G. Reinhard🇩🇪 · A. W. Thomas🇦🇺

    We report the first use of the effective QMC energy density functional (EDF), derived from a quark model of hadron structure, to study a broad range of ground state properties of even-even nuclei across the periodic table in the non-relativistic Hartree-Fock+BCS framework. The novelty of the QMC model is that the nuclear medium effects are treated through modification of the internal structure of the nucleon. The density dependence is microscopically derived and the spin-orbit term arises naturally. The QMC EDF depends on a single set of four adjustable parameters having clear physical basis. When applied to diverse ground state data the QMC EDF already produces, in its present simple form, overall agreement with experiment of a quality comparable to a representative Skyrme EDF. There exist however multiple Skyrme paramater sets, frequently tailored to describe selected nuclear phenomena. The QMC EDF set of fewer parameters, as derived in this work, is not open to such variation, chosen set being applied, without adjustment, to both the properties of finite nuclei and nuclear matter.

    Comments:
    9 pages, 1 table, 4 figures; in print in Phys. Rev. Letters. A minor change in the abstract, a few typos corrected and some small technical adjustments made to comply with the journal regulations
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1601.08131 [pdf]
    PRL(2016)·70 citations
  3. 03

    [Submitted on 29 Jan 2016]

    Predictions for TeV Pb+Pb Collisions from a Multi-Phase Transport Model

    Guo-Liang Ma🇨🇳 · Zi-Wei Lin🇺🇸

    We present predictions from the string melting version of a multi-phase transport model on various observables in Pb+Pb collisions at TeV. We use the same version of the model as an earlier study that reasonably reproduced dN/dy, -spectra and elliptic flow of charged pions and kaons at low- for central and semi-central heavy ion collisions at 200 GeV and 2.76 TeV. While we compare with the already-available centrality dependence data on charged particle at mid-pseudorapidity in Pb+Pb collisions at 5.02 TeV, we make predictions on identified particle dN/dy, -spectra, azimuthal anisotropies , and factorization ratios for longitudinal correlations.

    Comments:
    27 pages, 18 figures, added a new figure, v_2 analysis method modified for some figures; matches published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1601.08160 [pdf]
    PRC(2016)·106 citations
  4. 04

    [Submitted on 29 Jan 2016]

    Emergent properties of nuclei from ab initio coupled-cluster calculations

    G. Hagen · M. Hjorth-Jensen · G. R. Jansen · T. Papenbrock

    Emergent properties such as nuclear saturation and deformation, and the effects on shell structure due to the proximity of the scattering continuum and particle decay channels are fascinating phenomena in atomic nuclei. In recent years, ab initio approaches to nuclei have taken the first steps towards tackling the computational challenge of describing these phenomena from Hamiltonians with microscopic degrees of freedom. This endeavor is now possible due to ideas from effective field theories, novel optimization strategies for nuclear interactions, ab initio methods exhibiting a soft scaling with mass number, and ever-increasing computational power. This paper reviews some of the recent accomplishments. We also present new results. The recently optimized chiral interaction NNLO is shown to provide an accurate description of both charge radii and binding energies in selected light- and medium-mass nuclei up to Ni. We derive an efficient scheme for including continuum effects in coupled-cluster computations of nuclei based on chiral nucleon-nucleon and three-nucleon forces, and present new results for unbound states in the neutron-rich isotopes of oxygen and calcium. The coupling to the continuum impacts the energies of the states in O, and - contrary to naive shell-model expectations - the level ordering of the states in Ca.

    Comments:
    Contribution to the Special Physica Scripta Edition - 40 year anniversary - Nobel Prize '75, 27 pages, 7 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1601.08203 [pdf]
    Phys.Scripta(2016)·80 citations
  5. 05

    [Submitted on 29 Jan 2016]

    Uncertainty quantification of effective nuclear interactions

    R. Navarro Perez · J.E. Amaro · E. Ruiz Arriola

    We give a brief review on the development of phenomenological NN interactions and the corresponding quantification of statistical uncertainties. We look into the uncertainty of effective interactions broadly used in mean field calculations through the Skyrme parameters and effective field theory counter-terms by estimating both statistical and systematic uncertainties stemming from the NN interaction. We also comment on the role played by different fitting strategies on the light of recent developments.

    Comments:
    16 pages, 1 figure
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1601.08220 [pdf]
    IJMPE(2016)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE