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Nuclear Theory·nucl-th

Wednesday·February 27, 2019

6 papers—4 primary·2 cross-listed

All6Primary4Cross-lists2
  1. 01

    Time-dependent generator coordinate method study of mass-asymmetric fission of actinides

    Jie Zhao · Jian Xiang · Zhi-Pan Li · Tamara Nikšić · Dario Vretenar · Shan-Gui Zhou

    Low-energy positive and negative parity collective states in the equilibrium minimum, and the dynamics of induced fission of actinide nuclei are investigated in a unified theoretical framework based on the generator coordinate method (GCM) with the Gaussian overlap approximation (GOA). The collective potential and inertia tensor, both at zero and finite temperature, are computed using the self-consistent multidimensionally constrained relativistic mean field (MDC-RMF) model, based on the energy density functional DD-PC1. Pairing correlations are treated in the BCS approximation with a separable pairing force of finite range. A collective quadrupole-octupole Hamiltonian characterized by zero-temperature axially-symmetric deformation energy surface and perturbative cranking inertia tensor, is used to model the low-lying excitation spectrum. The fission fragment charge distributions are obtained by propagating the initial collective states in time with the time-dependent GCM+GOA that uses the same quadrupole-octupole Hamiltonian, but with the collective potential and inertia tensor computed at finite temperature. The illustrative charge yields of Th, U, Pu, Cm, and Cf are in very good agreement with experiment, and the predicted mass asymmetry is consistent with the result of a recent microscopic study that has attributed the distribution (peak) of the heavier-fragment nuclei to shell-stabilized octupole deformations.

    nucl-thPRC(2019)·44 citations
  2. 02

    Astrophysical -factor of the direct Li capture reaction in a three-body model

    E.M. Tursunov · Daniel Baye · S.A. Turakulov

    At the long-wavelength approximation, electric dipole transitions are forbidden between isospin-zero states. In an model with contributions, the Li astrophysical -factor is in agreement with the experimental data of the LUNA collaboration, without adjustable parameter. The exact-masses prescription used to avoid the disappearance of transitions in potential models is not founded at the microscopic level.

    nucl-thastro-ph.COSpringer Proc.Phys.(2020)·0 citations
  3. 03

    and reaction rates and the implication for Big Bang nucleosynthesis in the potential model

    S.A. Turakulov · E.M. Tursunov

    The reaction rates of the direct astrophysical capture processes and , as well as the abundance of the element are estimated in the framework of a two-body potential model. The estimated abundance ratio of is in a very good agreement with the recent measurement of the LUNA collaboration.

    nucl-thastro-ph.COInt.J.Mod.Phys.Conf.Ser.(2019)·2 citations
  4. 04

    Extension of nuclear landscape to hyperheavy nuclei

    S. E. Agbemava · A. V. Afanasjev · A. Taninah · A. Gyawali

    The properties of hyperheavy nuclei and the extension of nuclear landscape to hyperheavy nuclei are extensively studied within covariant density functional theory. Axial reflection symmetric and reflection asymmetric relativistic Hartree-Bogoliubov (RHB) calculations are carried out. The role of triaxiality is studied within triaxial RHB and triaxial relativistic mean field + BCS frameworks. With increasing proton number beyond Z~130 the transition from ellipsoidal-like nuclear shapes to toroidal ones takes place. The description of latter shapes requires the basis which is typically significantly larger than the one employed for the description of ellipsoidal-like shapes. Many hyperheavy nuclei with toroidal shapes are expected to be unstable towards multifragmentation. However, three islands of stability of spherical hyperheavy nuclei have been predicted for the first time in Ref. [1]. Proton and neutron densities, charge radii, neutron skins and underlying shell structure of the nuclei located in the centers of these islands have been investigated in detail. Large neutron shell gaps at N=228, 308 and 406 define approximate centers of these islands in neutron number. On the contrary, large proton gap appear only at Z=154 in the (Z~156, N~310) island. As a result, this is the largest island of stability of spherical hyperheavy nuclei found in the calculations. The calculations indicate the stability of the nuclei in these islands with respect of octupole and triaxial distortions. Fission barriers in neutron-rich superheavy nuclei are studied in triaxial RHB framework; the impact of triaxiality on the heights of fission barriers is substantial in some parts of this region. Based on the results obtained in the present work, the extension of nuclear landscape to hyperheavy nuclei is provided.

    nucl-thPRC(2019)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE