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Nuclear Theory·nucl-th

Wednesday·August 26, 2015

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 01

    [Submitted on 24 Aug 2015]

    A Method to Calculate Fission-Fragment Yields versus Proton and Neutron Number in the Brownian Shape-Motion Model. Application to calculations of U and Pu charge yields

    P. Moller · T. Ichikawa

    We propose a method to calculate the two-dimensional (2D) fission-fragment yield versus both proton and neutron number, with inclusion of odd-even staggering effects in both variables. The approach is to use Brownian shape-motion on a macroscopic-microscopic potential-energy surface which, for a particular compound system is calculated versus four shape variables: elongation (quadrupole moment ), neck , left nascent fragment spheroidal deformation , right nascent fragment deformation and two asymmetry variables, namely proton and neutron numbers in each of the two fragments. The extension of previous models 1) introduces a method to calculate this generalized potential-energy function and 2) allows the correlated transfer of nucleon pairs in one step, in addition to sequential transfer. In the previous version the potential energy was calculated as a function of and of the compound system and its shape, including the asymmetry of the shape. We outline here how to generalize the model from the "compound-system" model to a model where the emerging fragment proton and neutron numbers also enter, over and above the compound system composition.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1508.05964 [pdf]
    EPJA(2015)·35 citations
  2. 02

    [Submitted on 25 Aug 2015]

    Is hadronic flow produced in p--Pb collisions at the Large Hadron Collider?

    You Zhou🇩🇰 · Xiangrong Zhu🇨🇳 · Pengfei Li🇨🇳 · Huichao Song🇨🇳

    Using the Ultra-relativistic Quantum Molecular Dynamics ({\tt UrQMD}) model, we investigate the azimuthal correlations in p--Pb collisions at TeV. It is shown that the simulated hadronic p--Pb system can not generate the collective flow signatures, but mainly behaves as a non-flow dominant system. However, the characteristic mass-ordering of pions, kaons and protons is observed in {\tt UrQMD} simulations, which is the consequence of hadronic interactions and not necessarily associated with strong fluid-like expansions.

    Comments:
    4 pages, 4 figures, proceedings for the 12th International Conference on Nucleus-Nucleus Collisions (21-26 June 2015, Catania)
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1508.06160 [pdf]
    EPJ Web Conf.(2016)·0 citations
  3. 03

    [Submitted on 25 Aug 2015]

    Scaling functions of two-neutron separation energies of with finite range potentials

    M. A. Shalchi · M. R. Hadizadeh · M. T. Yamashita · Lauro Tomio · T. Frederico

    The behaviour of an Efimov excited state is studied within a three-body Faddeev formalism for a general neutron-neutron-core system, where neutron-core is bound and neutron-neutron is unbound, by considering zero-ranged as well as finite-ranged two-body interactions. For the finite-ranged interactions we have considered a one-term separable Yamaguchi potential. The main objective is to study range corrections in a scaling approach, with focus in the exotic carbon halo nucleus .

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1508.06258 [pdf]
    EPJ Web Conf.(2016)·0 citations
  4. 04

    [Submitted on 25 Aug 2015]

    Nuclear Mass Predictions for the Crustal Composition of Neutron Stars: A Bayesian Neural Network Approach

    R. Utama · J. Piekarewicz · H. B. Prosper

    Besides their intrinsic nuclear-structure value, nuclear mass models are essential for astrophysical applications, such as r-process nucleosynthesis and neutron-star structure. To overcome the intrinsic limitations of existing "state-of-the-art" mass models, we propose a refinement based on a Bayesian Neural Network (BNN) formalism. A novel BNN approach is implemented with the goal of optimizing mass residuals between theory and experiment. A significant improvement (of about 40%) in the mass predictions of existing models is obtained after BNN refinement. Moreover, these improved results are now accompanied by proper statistical errors. Finally, by constructing a "world average" of these predictions, a mass model is obtained that is used to predict the composition of the outer crust of a neutron star. The power of the Bayesian neural network method has been successfully demonstrated by a systematic improvement in the accuracy of the predictions of nuclear masses. Extension to other nuclear observables is a natural next step that is currently under investigation.

    Comments:
    13 pages, 5 figures, submitted to Physical Review C
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
    arXiv:
    1508.06263 [pdf]
    PRC(2016)·211 citations

Affiliations

first authorsco-authorsvia INSPIRE