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Nuclear Theory·nucl-th

Tuesday·May 22, 2018

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 01

    Theoretical considerations about heavy-ion fusion in potential scattering

    L. F. Canto · R. Donangelo · M. S. Hussein · J. Lubian · P. Lotti · J. Rangel

    We carefully compare the one-dimensional WKB barrier tunneling model, and the one-channel Schödinger equation with a complex optical potential calculation of heavy-ion fusion, for a light and a heavy system. It is found that the major difference between the two approaches occurs around the critical energy, above which the effective potential for the grazing angular momentum ceases to exhibit a pocket. The value of this critical energy is shown to be strongly dependent on the nuclear potential at short distances, on the inside region of the Coulomb barrier, and this dependence is much more important for heavy systems. Therefore the nuclear fusion process is expected to provide information on the nuclear potential in this inner region. We compare calculations with available data to show that the results are consistent with this expectation.

    nucl-thnucl-exPRC(2018)·15 citations
  2. 02

    Persistence of magicity in neutron rich exotic Ni in ground as well as excited states

    Mamta Aggarwal · G. Saxena

    Recent experimental observation of magicity in Ni has infused the interest to examine the persistence of the magic character across the N50 shell gap in extremely neutron rich exotic nucleus Ni in ground as well as excited states. A systematic study of Ni isotopes and N50 isotones in ground state is performed within the microscopic framework of relativistic mean-field (RMF) and the triaxially deformed Nilson Strutinsky model (NSM). Ground state density distributions, charge form factors, radii, separation energies, pairing energies, single particle energies and the shell corrections show strong magicity in Ni. Excited nuclei are treated within the statistical theory of hot rotating nuclei where the variation of level density parameter and entropy shows significant magicity with a deep minima at N50, which, persists up to the temperatures 1.52 MeV and then slowly disappear with increasing temperature. Rotational states are evaluated and effect of rotation on N50 (Z2030) isotones are studied. Our results agree very well with the available experimental data and few other theoretical calculations.

    nucl-thnucl-exIJMPE(2018)·4 citations
  3. 03

    Stability of the linear chain structure for C in covariant density functional theory on a 3D lattice

    Z. X. Ren · S. Q. Zhang · P. W. Zhao · N. Itagaki · J. A. Maruhn · J. Meng

    The stability of the linear chain structure of three clusters for C against the bending and fission is investigated in the cranking covariant density functional theory, in which the equation of motion is solved on a 3D lattice with the inverse Hamiltonian and the Fourier spectral methods. Starting from a twisted three initial configuration, it is found that the linear chain structure is stable when the rotational frequency is within the range of 2.0 MeV to 2.5 MeV. Beyond this range, the final states are not stable against fission. By examining the density distributions and the occupation of single-particle levels, however, these fissions are found to arise from the occupation of unphysical continuum with large angular momenta. To properly remove these unphysical continuum, a damping function for the cranking term is introduced. Eventually, the stable linear chain structure could survive up to the rotational frequency 3.5 MeV, but the fission still occurs when the rotational frequency approaches to 4.0 MeV.

    nucl-thnucl-exSCPMA(2019)·60 citations
  4. 04

    Precision of finite-difference representation in 3D coordinate-space Hartree-Fock-Bogoliubov calculations

    Yue Shi

    The current work plans to study the accuracy due to FD approximation to the 3D nuclear HFB problem. By (1) taking the wave functions solved in harmonic oscillator (HO) basis, (2) representing the HFB problem in coordinate space using FD method, the current work carefully evaluates the error due to box discretization by examining the deviation of the resulted HFB matrix, the total energies in the coordinate space, from those calculated with HO method, the latter of which is free from numerical error within its model configuration. To estimate how the error (given by the box discretization schemes suggested above) accumulates with self-consistent iterations, self-consistent HF and HFB calculations (with two-basis method) has been carried out for doubly magic nuclei, Ca, Sn, and Mo. The resulted total energies are compared with those of HO basis, and 3D coordinate space calculations in literatures. The analysis shows that, for grid spacing 0.6\,fm, the off-diagonal elements of the resulted HFB matrix elements (M.E.) are extremely small (1\,keV). The resulted quasi-particle (q.p.) spectra differ from those of HO calculations by a few keV. Self-consistent HF and HFB calculations within the current FD method with the above box discretizatioin schemes give results similar to those calculations of existing HO basis, and coordinate space method.

    nucl-thPRC(2018)·7 citations
  5. 05

    Two-body dissipation effect in nuclear fusion reactions

    Kai Wen · M. C. Barton · Arnau Rios · P. D. Stevenson

    Friction coefficients for the fusion reaction O+O S are extracted based on both the time-dependent Hartree-Fock and the time-dependent density matrix methods. The latter goes beyond the mean-field approximation by taking into account the effect of two-body correlations, but in practical simulations of fusion reactions we find that the total energy is not conserved. We analyze this problem and propose a solution that allows for a clear quantification of dissipative effects in the dynamics. Compared to mean-field simulations, friction coefficients in the density-matrix approach are enhanced by about . An energy-dependence of the dissipative mechanism is also demonstrated, indicating that two-body collisions are more efficient at generating friction at low incident energies.

    nucl-thPRC(2018)·24 citations

Affiliations

first authorsco-authorsvia INSPIRE