Nuclear Theory·nucl-th

Monday·May 10, 2021

15 papers—5 primary·10 cross-listed

01
[Submitted on 7 May 2021]
Drastic change in inelastic scattering depending on the development of dineutron correlation in $^{10}$ Be
T. Furumoto · T. Suhara · N. Itagaki
We investigated the development and breaking of the dineutron correlation in $^{10}$ Be by analyzing the elastic and inelastic scatterings with a framework combing the microscopic structure and reaction models. For studying the structure, the $^{10}$ Be nucleus was constructed under the assumption of a four-body ( $α + α + n + n$ ) cluster model. In this work, we focused on the change in the inner structure for the 0 $_{1}^{+}$ , 2 $_{1}^{+}$ , and 2 $_{2}^{+}$ states when the strength of the spin-orbit interaction is varied. The inner structure, including various physical quantities such as energy, radius, and transition strength, is drastically influenced by the strength of the spin-orbit interaction. In particular, the development and breaking of the dineutron correlation is governed by the spin-orbit strength. The differences in the inner structure can be manifested by applying the obtained wave functions to elastic and inelastic scatterings with a proton target at $E / A =$ 59.4 and 200 MeV. Although the 0 $_{1}^{+}$ and 2 $_{1}^{+}$ states are significantly influenced by the spin-orbit strength of the nuclear structure calculation, the elastic and inelastic cross sections are not much affected. On the other hand, the inelastic cross section of the 2 $_{2}^{+}$ state depends greatly on the spin-orbit strength of the structure calculation. Thus, we discovered a way to measure the degree of the development of dineutron cluster structure based on its sensitivity to the inelastic cross section of the 2 $_{2}^{+}$ state of $^{10}$ Be.
Comments:
22 pages, 7 figures, accepted for publication in Physical Review C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2105.03025 [pdf]
PRC(2021)·6 citations
02
[Submitted on 7 May 2021]
Coulomb screening effect on the Hoyle state energy in thermal plasmas
Lai Hnin Phyu · H. Moriya · W. Horiuchi · K. Iida · K. Noda · M. T. Yamashita
The first excited $J^{π} = 0^{+}$ state of $^{12}$ C, the so-called Hoyle state, plays an essential role in a triple- $α$ ( $^{4}$ He) reaction, which is a main contributor to the synthesis of $^{12}$ C in a burning star. We investigate the Coulomb screening effects on the energy shift of the Hoyle state in a thermal plasma environment using precise three- $α$ model calculations. The Coulomb screening effect between $α$ clusters are taken into account within the Debye-Hückel approximation. To generalize our study, we utilize two standard $α$ -cluster models, which treat the Pauli principle between the $α$ particles differently. We find that the energy shifts do not depend on these models and follow a simple estimation in the zero-size limit of the Hoyle state when the Coulomb screening length is as large as a value typical of such a plasma consisting of electrons and $α$ particles.
Comments:
6 pages, 2 figures, contribution to the 8th Asia-Pacific Conference on Few-Body Problems in Physics (APFB2020), 1-5 March 2021, Kanazawa, Japan
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2105.03031 [pdf]
Few Body Syst.(2021)·2 citations
03
[Submitted on 7 May 2021]
Pairing and nonaxial-shape correlations in $N = 150$ isotones
Kenichi Yoshida🇯🇵
Background: The $K^{π} = 2^{-}$ excited band emerges systematically in $N = 150$ isotones raging from Pu to No with even- $Z$ numbers, and a sharp drop in energies was observed in Cf. Purpose: I attempt to uncover the microscopic mechanism for the appearance of such a low-energy $2^{-}$ state in $^{248}$ Cf. Furthermore, I investigate the possible occurrence of the low-energy $K^{π} = 2^{+}$ state to elucidate the mechanism that prefers the simultaneous breaking of the reflection and axial symmetry to the breaking of the axial symmetry alone in this mass region. Method: I employ a nuclear EDF method: the Skyrme-Kohn-Sham-Bogoliubov and the quasiparticle random-phase approximation are used to describe the ground state and the transition to excited states. Results: The Skyrme-type SkM* and SLy4 functionals reproduce the fall in energy, but not the absolute value, of the $K^{π} = 2^{-}$ state at $Z = 98$ , where the proton 2qp excitation $[633] 7/2 \otimes [521] 3/2$ plays a decisive role for the peculiar isotonic dependence. I find interweaving roles by the pairing correlation of protons and the deformed shell closure at $Z = 98$ . The SkM* model predicts the $K^{π} = 2^{-}$ state appears lower in energy in $^{246}$ Cf than in $^{248}$ Cf as the Fermi level of neutrons is located in between the $[622] 5/2$ and $[734] 9/2$ orbitals. Except for $^{250}$ Fm in the SkM* calculation, the $K^{π} = 2^{+}$ state is predicted to appear higher in energy than the $K^{π} = 2^{-}$ state because the quasi-proton $[521] 1/2$ orbital is located above the $[633] 7/2$ orbital. Conclusions: A systematic study of low-lying collective states in heavy actinide nuclei provides a rigorous testing ground for microscopic nuclear models. The present study shows a need for improvements in the EDFs to describe pairing correlations and shell structures in heavy nuclei, that are indispensable in predicting the heaviest nuclei.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2105.03128 [pdf]
PRC(2021)·5 citations
04
[Submitted on 18 Apr 2021]
Limits on active-sterile neutrino mixing parameters using heavy nuclei abundances
M. M. Saez🇦🇷 · K. J. Fushimi🇦🇷 · M. E. Mosquera🇦🇷 · O. Civitarese🇦🇷
The production of heavy-mass elements due to the rapid neutron-capture mechanism (r-process) is associated with astrophysical scenarios, such as supernovae and neutron-star mergers. In the r-process the capture of neutrons is followed by $β$ -decays until nuclear stability is reached. A key element in the chain of nuclear weak-decays leading to the production of isotopes may be the change of the parameters controlling the neutrino sector, due to the mixing of active and sterile species. In this work we have addressed this question and calculated $β$ -decay rates for the nuclei involved in the r-process chains as a function of the neutrino mixing parameters. These rates were then used in the calculation of the abundance of the heavy elements produced in core-collapse supernova and in neutron-star mergers, starting from different initial mass-fraction distributions. The analysis shows that the core-collapse supernova environment contributes with approximately $30%$ of the total heavy nuclei abundance while the neutron-star merger contributes with about $70%$ of it. Using available experimental data we have performed a statistical analysis to set limits on the active-sterile neutrino mixing angle and found a best-fit value $sin^{2} 2 θ_{14} = 0.22$ , a value comparable with those found in other studies reported in the literature.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2105.03202 [pdf]
IJMPE(2021)·1 citation
05
[Submitted on 7 May 2021]
Fluctuations in the pasta phase
Mateus R. Pelicer🇧🇷 · Débora P. Menezes🇧🇷 · Celso C. Barros Jr🇧🇷 · Francesca Gulminelli🇫🇷
Baryonic matter close to the saturation density is very likely to present complex inhomogeneous structures collectively known under the name of pasta phase. At finite temperature, the different geometric structures are expected to coexist, with potential consequences on the neutron star crust conductivity and neutrino transport in supernova matter. In the framework of a statistical multi-component approach, we calculate the composition of matter in the pasta phase considering density, proton fraction, and geometry fluctuations. Using a realistic energy functional from relativistic mean field theory and a temperature and isospin dependent surface tension fitted from Thomas-Fermi calculations, we show that different geometries can coexist in a large fraction of the pasta phase, down to temperatures of the order of the crystallization temperature of the neutron star crust. Quantitative estimates of the charge fluctuations are given.
Comments:
6 pages, 3 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2105.03318 [pdf]
PRC(2021)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Drastic change in inelastic scattering depending on the development of dineutron correlation in 10Be

Coulomb screening effect on the Hoyle state energy in thermal plasmas

Pairing and nonaxial-shape correlations in N=150 isotones

Limits on active-sterile neutrino mixing parameters using heavy nuclei abundances

Fluctuations in the pasta phase

Affiliations

Drastic change in inelastic scattering depending on the development of dineutron correlation in $^{10}$ Be

Pairing and nonaxial-shape correlations in $N = 150$ isotones