Nuclear Theory·nucl-th

Wednesday·November 29, 2023

10 papers—5 primary·5 cross-listed

01
[Submitted on 28 Nov 2023]
Variation of multi-Slater determinants in antisymmetrized molecular dynamics and its application to $^{10}$ Be with various clustering
Takayuki Myo · Mengjiao Lyu · Qing Zhao · Masahiro Isaka · Niu Wan · Hiroki Takemoto · Hisashi Horiuchi
We propose a method to optimize the multi-Slater determinants of the antisymmetrized molecular dynamics (AMD) in the linear combination form and apply it to the neutron-rich $^{10}$ Be nucleus. The individual Slater determinants and their weights in the superposition are determined simultaneously according to the variational principle of the energy of the total wave function. The multi-AMD basis states of $^{10}$ Be show various cluster structures as well as the shell-model type. In the cluster configurations, different intercluster distances are superposed automatically indicating the role of the generator coordinates. We further introduce a procedure to obtain the configurations for the excited states imposing the orthogonal condition to the ground-state configurations. In the excited states of $^{10}$ Be, the linear-chain-like structure is confirmed consisting of various clusters. The energy spectrum using the obtained basis states reproduces the experiments. The present framework can be the method to find the optimal multi-configuration for nuclear ground and excited states.
Comments:
13 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2311.16391 [pdf]
PRC(2023)·16 citations
02
[Submitted on 28 Nov 2023]
Exotic nonaxial-octupole shapes in $N = 184$ isotones from covariant density functional theories
Jie Zhao · Zheng-Gang Wu
The nonaxial octupole shape in some nuclei with $N = 184$ , namely, $^{284}$ Fm, $^{286}$ No, $^{288}$ Rf, and $^{290}$ Sg, is investigated using covariant density functional theories. Employing the density-dependent point-coupling covariant density functional theory with the parameter set DD-PC1 in the particle-hole channel, it is found that the ground states of $^{284}$ Fm, $^{286}$ No, $^{288}$ Rf, and $^{290}$ Sg have pure nonaxial octupole shapes with deformation parameters $β_{31} \approx 0.08$ and $β_{33} \approx - 0.01 \sim - 0.03$ . The energy gain due to the $β_{31}$ and $β_{33}$ distortion is $\sim$ 1 MeV. The occurrence of the nonaxial octupole correlations is mainly from the proton orbitals $1 i_{13/2}$ and $2 f_{7/2}$ , which are close to the proton Fermi surface. The dependence of the nonaxial octupole effects on the form of the energy density functional and on the parameter set is also studied.
Comments:
7 pages, 4 figures, accepted for publication in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2311.16425 [pdf]
PRC(2024)·7 citations
03
[Submitted on 28 Nov 2023]
Fusion and reactions of $α$ + $^{8}$ Be in the Hoyle resonance and associated resonances region
Teck-Ghee Lee · Orhan Bayrak · Cheuk-Yin Wong
The fusion of $α$ and $^{8}$ Be to produce a $^{12}$ C nucleus is a crucial process in nucleosynthesis. In the laboratory, this process can only be studied theoretically as a $^{8}$ Be target or projectile cannot be prepared experimentally. We use the potential scattering theory in the coupled-channel formalism to study such a process in terms of the collision between the $α$ particle on a deformed $^{8}$ Be nucleus, both on resonance and off resonance in the Hoyle resonance and associated resonances region. The experimental $^{12}$ C energy levels and widths constrain the nuclear potential to suggest the need to include a parity-dependent surface potential component that is more attractive for even- $L$ positive-parity partial waves than for odd- $L$ negative-parity partial waves. As a consequence, the radial dependence of the total potentials for the set of \{0 $^{+}$ , 2 $^{+}$ , 4 $^{+}$ \} resonances of $^{12}$ C exhibit a double-hump behavior, possessing two local energy minima and a doublet of each of the $^{12}$ C \{0 $^{+}$ , 2 $^{+}$ , 4 $^{+}$ \} resonances in the Hoyle and associated resonances region. We examine the approximate agreement of the theoretical results with experiment and suggest the search for the as-yet unobserved lower-energy 2 $_{2}^{+}$ and 4 $_{1}^{+}$ resonances to test the double-hump potential description. In addition, for practical astrophysical applications, we evaluate and estimate the astrophysical $S (E_{c.m.})$ -factor for the $α$ + $^{8}$ Be $\to$ $^{12}$ C $(0^{+*})$ $\to$ $^{12}$ C $(2_{1}^{+})$ + $γ$ reaction for $E_{c.m.}$ $<$ 1.0 MeV.
Comments:
21 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Quantum Physics (quant-ph)
arXiv:
2311.16837 [pdf]
PRC(2026)·0 citations
04
[Submitted on 28 Nov 2023]
Universality in Ground State Masses of Nuclei
A. Bhagwat · Sudhir Ranjan Jain
The beautiful and profound result that the first eigenvalue of Schroedinger operator can be interpreted as a large deviation of certain kind of Brownian motion leads to possible existence of universality in the distribution of ground state energies of quantal systems. Existence of such universality is explored in the distribution of the ground state energies of nuclei with Z $\geq$ 8 and N $\geq$ 8. Specifically, it has been demonstrated that the nuclear masses follow extreme-value statistics, implying that the nuclear ground state energies indeed can be treated as extreme values in the sense of the large deviation theory of Donsker and Varadhan.
Subjects:
Nuclear Theory (nucl-th); Statistical Mechanics (cond-mat.stat-mech); Quantum Physics (quant-ph)
arXiv:
2311.16929 [pdf]
0 citations
05
[Submitted on 28 Nov 2023]
Adding Corrections to Global Spherical Potentials for Use in a Coupled-Channel Formulation
S. P. Weppner · Prakrut Patel · C. Miller · C. Ogg · I. Mazumdar
The coupled-channel technique augments a non-relativistic distorted wave born approximation scattering calculation to include a coupling to virtual states from the negative energy region. It has been found to be important in low energy nucleon-nucleus scattering. We modify the nucleon-nucleus standard optical potentials, not designed for a coupled-channel space, so they can be used in that setting. The changes are small and systematic. We use a standard scattering code to adjust a variety of optical potentials and targets such that the original fit to scattering observables are maintained as we incorporate the coupled-channel environment. Overall over forty target nuclei were tested from $A = 12$ to $A = 205$ and nucleon projectile energies from 1 MeV to 200 MeV. There is excellent improvement in fitting the scattering observables, especially for low energy neutron scattering.The corrections were found to be unimportant for projectile energies greater than 200 MeV. The largest changes are to the surface amplitudes while the real radii and the real central amplitude are modified by only a few percent, every other parameter is unchanged. This technique is general enough to be applied to a variety of inelastic theoretical calculations.
Comments:
Second draft, not yet submitted to a journal in this form
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2311.16969 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Variation of multi-Slater determinants in antisymmetrized molecular dynamics and its application to 10Be with various clustering

Exotic nonaxial-octupole shapes in N=184 isotones from covariant density functional theories

Fusion and reactions of α+8Be in the Hoyle resonance and associated resonances region

Universality in Ground State Masses of Nuclei

Adding Corrections to Global Spherical Potentials for Use in a Coupled-Channel Formulation

Affiliations

Variation of multi-Slater determinants in antisymmetrized molecular dynamics and its application to $^{10}$ Be with various clustering

Exotic nonaxial-octupole shapes in $N = 184$ isotones from covariant density functional theories

Fusion and reactions of $α$ + $^{8}$ Be in the Hoyle resonance and associated resonances region