Nuclear Theory·nucl-th

Friday·October 16, 2020

10 papers—5 primary·5 cross-listed

01
Probing negative-parity states of $^{24}$ Mg probed via proton and alpha inelastic scattering
Yoshiko Kanada-En'yo · Kazuyuki Ogata
[Background:] The band structure of the negative-parity states of $^{24}$ Mg has not yet been clarified. The $K^{π} = 0^{-}$ , $K^{π} = 1^{-}$ , and $K^{π} = 3^{-}$ bands have been suggested, but the assignments have been inconsistent between experiments and theories. [Purpose:] Negative-parity states of $^{24}$ Mg are investigated by microscopic structure and reaction calculations via proton and alpha inelastic scattering to clarify the band assignment for the observed negative-parity spectra. [Method:] The structure of $^{24}$ Mg was calculated using the antisymmetrized molecular dynamics~(AMD). Proton and alpha inelastic reactions were calculated using microscopic coupled-channel (MCC) calculations by folding the Melbourne $g$ -matrix $N N$ interaction with the AMD densities of $^{24}$ Mg. [Results:] The member states of the $K^{π} = 0^{+}$ , $K^{π} = 2^{+}$ , $K^{π} = 0^{-}$ , $K^{π} = 1^{-}$ , and $K^{π} = 3^{-}$ bands of $^{24}$ Mg were obtained through the AMD result. In the MCC+AMD results for proton and alpha elastic and inelastic cross sections, reasonable agreements were obtained with existing data, except in the case of the $4_{1}^{+}$ state. [Conclusions:] The $3^{-}$ state of the $K^{π} = 3^{-}$ band and the $1^{-}$ and $3^{-}$ states of the $K^{π} = 0^{-}$ bands were assigned to the $3_{1}^{-}$ (7.62 MeV), $1_{1}^{-}$ (7.56 MeV), and $3_{2}^{-}$ (8.36 MeV) states, respectively. The present AMD calculation is the first microscopic structure calculation to reproduce the energy ordering of the $K^{π} = 0^{-}$ , $K^{π} = 1^{-}$ , and $K^{π} = 3^{-}$ bands of $^{24}$ Mg.
nucl-thPRC(2021)·10 citations
02
Sensitivity of transfer cross sections to the bound-state wave functions
Shubhchintak · P. Descouvemont
We test the sensitivity of transfer reactions to the bound state wave functions within a distorted wave Born approximation formalism. Using supersymmetric transformations, we remove the Pauli-forbidden states from the two-body potentials and generate an equivalent supersymmetric partner. Wave functions from these potentials have the same asymptotics, but they differ in the nuclear interior. This allows us to study the influence of the nuclear interior on transfer cross sections. We apply the calculations to the $^{16}$ O( $d, p$ ) $^{17}$ O and $^{12}$ C( $^{7}$ Li, $t$ ) $^{16}$ O reactions, which are typical examples of nucleon and $α$ transfer, respectively. The spectroscopic factors for $^{17}$ O are decreased by about 30\% when using supersymmetric potentials. For $^{16}$ O, the differences are smaller. However, we show that ambiguities exist in the determination of the spectroscopic factors, due to the choice of the angular range where the fit is performed.
nucl-thnucl-exPLB(2020)·9 citations
03
Proton and neutron skins and symmetry energy of mirror nuclei
M.K. Gaidarov · I. Moumene · A.N. Antonov · D.N. Kadrev · P. Sarriguren · E. Moya de Guerra
The neutron skin of nuclei is an important fundamental property, but its accurate measurement faces many challenges. Inspired by charge symmetry of nuclear forces, the neutron skin of a neutron-rich nucleus is related to the difference between the charge radii of the corresponding mirror nuclei. We investigate this relation within the framework of the Hartree-Fock-Bogoliubov method with Skyrme interactions. Predictions for proton skins are also made for several mirror pairs in the middle mass range. For the first time the correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated simultaneously for nuclei and their corresponding mirror partners. As an example, the Ni isotopic chain with mass number $A = 48 - 60$ is considered. These quantities are calculated within the coherent density fluctuation model using Brueckner and Skyrme energy-density functionals for isospin asymmetric nuclear matter with two Skyrme-type effective interactions, SkM* and SLy4. Results are also presented for the symmetry energy as a function of $A$ for a family of mirror pairs from selected chains of nuclei with $Z = 20$ , $N = 14$ , and $N = 50$ . The evolution curves show a similar behavior crossing at the $N = Z$ nucleus in each chain and a smooth growing deviation when $N \neq = Z$ starts. Comparison of our results for the radii and skins with those from the calculations based on high-precision chiral forces is made.
nucl-thNPA(2020)·26 citations
04
Nuclear collective dynamics in transport model with the lattice Hamiltonian method
Rui Wang · Zhen Zhang · Lie-Wen Chen · Yu-Gang Ma
We review the recent progress on studying the nuclear collective dynamics by solving the Boltzmann-Uehling-Uhlenbeck (BUU) equation with the lattice Hamiltonian method treating the collision term by the full-ensemble stochastic collision approach. This lattice BUU (LBUU) method has recently been developed and implemented in a GPU parallel computing technique, and achieves a rather stable nuclear ground-state evolution and high accuracy in evaluating the nucleon-nucleon (NN) collision term. This new LBUU method has been applied to investigate the nuclear isoscalar giant monopole resonances and isovector giant dipole resonances. While the calculations with the LBUU method without the NN collision term (i.e., the lattice Hamiltonian Vlasov method) describe reasonably the excitation energies of nuclear giant resonances, the full LBUU calculations can well reproduce the width of the giant dipole resonance of $^{208}$ Pb by including a collisional damping from NN scattering. The observed strong correlation between the width of nuclear giant dipole resonance and the NN elastic cross section suggests that the NN elastic scattering plays an important role in nuclear collective dynamics, and the width of nuclear giant dipole resonance provides a good probe of the in-medium NN elastic cross section.
nucl-thastro-ph.HEnucl-exFront.in Phys.(2020)·15 citations
05
A fully microscopic model of total level density in spherical nuclei
N. Quang Hung · N. Dinh Dang · L. Tan Phuc · N. Ngoc Anh · T. Dong Xuan · T. V. Nhan Hao
A fully microscopic model for the description of nuclear level density (NLD) in spherical nuclei is proposed. The model is derived by combining the partition function of the exact pairing solution plus the independent-particle model at finite temperature (EP+IPM) with that obtained by using the collective vibrational states calculated from the self-consistent Hartree-Fock mean field with MSk3 interaction plus the exact pairing and random-phases approximation (SC-HFEPRPA). Two important factors are taken into account in a fully microscopic way, namely the spin cut-off and vibrational enhancement factors are, respectively, calculated using the statistical thermodynamics and partition function of the SC-HFEPRPA without any fitting parameters. The numerical test for two spherical $^{60}$ Ni and $^{90}$ Zr nuclei shows that the collective vibrational enhancement is mostly dominated by the quadrupole and octupole excitations. This is the first microscopic model confirming such an effect, which was phenomenologically predicted long time ago and widely employed in several NLD models. In addition, the influence of collective vibrational enhancement on nuclear thermodynamic quantities such as excitation energy, specific heat capacity and entropy is also studied by using the proposed model.
nucl-thPLB(2020)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE

Probing negative-parity states of 24Mg probed via proton and alpha inelastic scattering

Sensitivity of transfer cross sections to the bound-state wave functions

Proton and neutron skins and symmetry energy of mirror nuclei

Nuclear collective dynamics in transport model with the lattice Hamiltonian method

A fully microscopic model of total level density in spherical nuclei

Affiliations

Probing negative-parity states of $^{24}$ Mg probed via proton and alpha inelastic scattering