Nuclear Theory·nucl-th

Thursday·October 27, 2022

9 papers—5 primary·4 cross-listed

01
[Submitted on 25 Oct 2022]
Bulk and decay properties of neutron-deficient odd-mass Hg isotopes around A = 185
O. Moreno · P. Sarriguren · A. Algora · L. M. Fraile · S. E. A. Orrigo
Ground and isomeric states of the neutron-deficient odd- $A$ isotopes $^{183}$ Hg, $^{185}$ Hg, and $^{187}$ Hg are described from a microscopic calculation based on a self-consistent, axially-deformed Hartree-Fock mean field with the Skyrme functional and pairing within BCS approximation. For each equilibrium shape and different odd-neutron states, results on mean square charge radii and magnetic dipole moments are given and analyzed in the context of their sensitivity to the nuclear deformation and to the spin and parity. Spin-isospin correlations within proton-neutron quasiparticle random phase approximation are then introduced in the nuclear states to obtain the distributions of Gamow-Teller strength and the $β^{+} / E C$ half-lives of these isotopes, whose measurements are planned at ISOLDE-CERN using total absorption gamma-ray spectroscopy techniques.
Comments:
11 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2210.14285 [pdf]
PRC(2022)·3 citations
02
[Submitted on 25 Oct 2022]
Proton-neutron entanglement in the nuclear shell model
Calvin W. Johnson · Oliver C. Gorton
We compute the proton-neutron entanglement entropy in the interacting nuclear shell model for a variety of nuclides and interactions. Some results make intuitive sense, for example that the shell structure, as governed by single-particle and monopole energies, strongly affects the energetically available space and thus the entanglement entropy. We also find a surprising result: that the entanglement entropy at low excitation energy tends to decrease for nuclides when $N \neq = Z$ . While we provide evidence this arises from the physical nuclear force by contrasting with random two-body interactions which shows no such decrease, the exact mechanism is unclear. Nonetheless, the low entanglement suggests that in models of neutron-rich nuclides, the coupling between protons and neutrons may be less computationally demanding than one might otherwise expect.
Comments:
13 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2210.14338 [pdf]
J.Phys.G(2023)·65 citations
03
[Submitted on 25 Oct 2022]
Bayesian Estimation of the $S$ Factor and Thermonuclear Reaction Rate for $^{16}$ O(p, $γ$ ) $^{17}$ F
Christian Iliadis · Vimal Palanivelrajan · Rafael S. de Souza
The $^{16}$ O(p, $γ$ ) $^{17}$ F reaction is the slowest hydrogen-burning process in the CNO mass region. Its thermonuclear rate sensitively impacts predictions of oxygen isotopic ratios in a number of astrophysical sites, including AGB stars. The reaction has been measured several times at low bombarding energies using a variety of techniques. The most recent evaluated experimental rates have a reported uncertainty of about 7.5\% below $1$ ~GK. However, the previous rate estimate represents a best guess only and was not based on rigorous statistical methods. We apply a Bayesian model to fit all reliable $^{16}$ O(p, $γ$ ) $^{17}$ F cross section data, and take into account independent contributions of statistical and systematic uncertainties. The nuclear reaction model employed is a single-particle potential model involving a Woods-Saxon potential for generating the radial bound state wave function. The model has three physical parameters, the radius and diffuseness of the Woods-Saxon potential, and the asymptotic normalization coefficients (ANCs) of the final bound state in $^{17}$ F. We find that performing the Bayesian $S$ factor fit using ANCs as scaling parameters has a distinct advantage over adopting spectroscopic factors instead. Based on these results, we present the first statistically rigorous estimation of experimental $^{16}$ O(p, $γ$ ) $^{17}$ F reaction rates, with uncertainties ( $\pm 4.2$ \%) of about half the previously reported values.
Comments:
3 figures
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
2210.14354 [pdf]
PRC(2022)·10 citations
04
[Submitted on 26 Oct 2022]
Effects of nucleon-nucleon short-range correlations on inclusive electron scattering
Qinglin Niu · Jian Liu · Yuanlong Guo · Chang Xu · Mengjiao Lyu · Zhongzhou Ren
The nucleon-nucleon short-range correlation NN-SRC is one of the key issues of nuclear physics, which typically manifest themselves in high-momentum components of the nuclear momentum distributions. In this letter, the nuclear spectral functions based on the axially deformed relativistic mean-field model are developed to involve the NN-SRC. With the spectral functions, the inclusive electron scattering $(e, e^{'})$ cross sections are calculated within the PWIA framework, including the quasi-elastic (QE) part and $Δ$ production part. Especially in the $Δ$ production region, we reconsider the electromagnetic structures of the nucleon resonance $Δ$ (1232) and the scattering mechanisms, thereby the theoretical calculations are improved effectively and the cross sections are well consistent with the experimental data. The theoretical $(e, e^{'})$ cross sections are further divided into NN-SRC and mean-field contributions. It is found that, at the kinematics $0.5 GeV^{2} < Q^{2} < 1 GeV^{2}$ , the QE peak and $Δ$ production peak not only reflect the mean-field structure, but also are sensitive to the NN-SRC information. Finally, we provide a new method to extract the strengths of NN-SRC from experimental cross sections for selected nuclei at the suitable kinematics.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2210.14444 [pdf]
PRC(2022)·13 citations
05
[Submitted on 26 Oct 2022]
Exploring sensitivity of charge-exchange ( $p, n$ ) reactions to the neutron density distribution
Jian Liu · Yunsheng Wang · Yonghao Gao · Pawel Danielewicz · Chang Xu · Zhongzhou Ren
$B a c k g r o u n d :$ The determination of the nuclear neutron properties suffers from uncontrolled uncertainties, which attracted considerable attention recently, such as in the context of the PREX experiment. $P u r p ose :$ Our aim is to analyze the sensitivity of charge-exchange ( $p, n$ ) reactions to the neutron density distribution $ρ_{n}$ and constrain the neutron characteristics in the nuclear structure models. $M e t h o d :$ By combing the folding and the mean-field models, the nucleon-nucleus ( $N A$ ) potential can be obtained from the nuclear density distribution. Further, the ( $p, p$ ) and ( $p, n$ ) cross sections for $^{48}$ Ca and $^{208}$ Pb are calculated following the distorted-wave Born approximation (DWBA) method. $R es u l t s :$ Compared with the ( $p, p$ ) cross section, the effects of $ρ_{n}$ variation on the ( $p, n$ ) cross section are significant, which is due to the impact of isovector properties. Based on the global folding model analyses of data, it is found that $^{48}$ Ca and $^{208}$ Pb have relatively large neutron skin thickness $Δ R_{n p}$ . $C o n c l u s i o n s :$ Results illustrate that the charge-exchange ( $p, n$ ) reaction is a sensitive probe of $ρ_{n}$ . The results in this paper can offer useful guides for future experiments of neutron characteristics.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2210.14554 [pdf]
PRC(2022)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE

Bulk and decay properties of neutron-deficient odd-mass Hg isotopes around A = 185

Proton-neutron entanglement in the nuclear shell model

Bayesian Estimation of the S Factor and Thermonuclear Reaction Rate for 16O(p,γ)17F

Effects of nucleon-nucleon short-range correlations on inclusive electron scattering

Exploring sensitivity of charge-exchange (p,n) reactions to the neutron density distribution

Affiliations

Bayesian Estimation of the $S$ Factor and Thermonuclear Reaction Rate for $^{16}$ O(p, $γ$ ) $^{17}$ F

Exploring sensitivity of charge-exchange ( $p, n$ ) reactions to the neutron density distribution