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Nuclear Theory·nucl-th

Tuesday·February 6, 2018

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 01

    [Submitted on 4 Feb 2018]

    Characterizing the astrophysical S-factor for C+C with wave-packet dynamics

    Alexis Diaz-Torres · Michael Wiescher

    A quantitative study of the astrophysically important sub-barrier fusion of C+C is presented. Low-energy collisions are described in the body-fixed reference frame using wave-packet dynamics within a nuclear molecular picture. A collective Hamiltonian drives the time propagation of the wave-packet through the collective potential-energy landscape. The fusion imaginary potential for specific dinuclear configurations is crucial for understanding the appearance of resonances in the fusion cross section. The theoretical sub-barrier fusion cross sections explain some observed resonant structures in the astrophysical S-factor. These cross sections monotonically decline towards stellar energies. The structures in the data that are not explained are possibly due to cluster effects in the nuclear molecule, which are to be included in the present approach.

    Comments:
    Submitted to Physical Review C; 7 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1802.01160 [pdf]
    PRC(2018)·57 citations
  2. 02

    [Submitted on 4 Feb 2018]

    Effects of unconventional breakup modes on incomplete fusion of weakly bound nuclei

    Alexis Diaz-Torres · Daanish Quraishi

    The incomplete fusion dynamics of Li + Bi collisions at energies above the Coulomb barrier is investigated. The classical dynamical model implemented in the {\sc platypus} code is used to understand and quantify the impact of both Li resonance states and transfer-triggered breakup modes (involving short-lived projectile-like nuclei such as Be and Li) on the formation of incomplete fusion products. Model calculations explain the experimental incomplete-fusion excitation function fairly well, indicating that (i) delayed direct breakup of Li reduces the incomplete fusion cross-sections, and (ii) the neutron-stripping channel practically determines those cross-sections.

    Comments:
    Accepted in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1802.01181 [pdf]
    PRC(2018)·27 citations
  3. 03

    [Submitted on 5 Feb 2018]

    U(n, f) Independent Fission Product Yield and Isomeric Ratio Calculated with the Statistical Hauser-Feshbach Theory

    Shin Okumura · Toshihiko Kawano · Patrick Talou · Patrick Jaffke · Satoshi Chiba

    We have developed a Hauser-Feshbach fission fragment decay model, HFD, which can be applied to the statistical decay of more than 500 primary fission fragment pairs (1,000 nuclides) produced by the neutron induced fission of U. The fission fragment yield and the total kinetic energy TKE are model inputs, and we estimate them from available experimental data for the U(n,f) system. The model parameters in the statistical decay calculation are adjusted to reproduce some fission observables, such as the neutron emission multiplicity , its distribution , and the mass dependence . The calculated fission product yield and isomeric ratio are compared with experimental data. We show that the calculated independent fission product yield at the thermal energy reproduces the experimental data well, while the calculated isomeric ratios tend to be lower than the Madland-England model prediction. The model is extended to higher incident neutron energies up to the second chance fission threshold. We demonstrate for the first time that most of the isomeric ratios stay constant, although the production of isomeric state itself changes as the incident energy increases.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1802.01248 [pdf]
    J.Nucl.Sci.Tech.(2018)·56 citations

Affiliations

first authorsco-authorsvia INSPIRE