Nuclear Theory·nucl-th

Wednesday·July 19, 2023

17 papers—8 primary·9 cross-listed

01
[Submitted on 15 Jul 2023]
On the problems of creating a nuclear-optical frequency standard based on 229Th
F. F. Karpeshin · L. F. Vitushkin
The most probable candidate for the role of a nuclear optical standard is the 8.338-eV isomer of the 229mTh isotope of the thorium nucleus. Ways of using the resonance properties of the electron shell as an optical resonator to create laser-nuclear technologies necessary for the optical pumping of nuclear isomers and other manipulations of atomic nuclei leading to the creation of a next-generation frequency standard and nuclear-optical clocks based on them are discussed. Deep relations between the physics of resonance electron-nuclear interactions and the true solution of the thorium puzzle are shown. The article discusses important principles of resonant optical pumping, such as the presence of a finite width in the intermediate electronic state, and others that are usually overlooked with a fatal result for the experiment. The wide application of the various physics of these processes will predetermine a revolutionary leap in the development of new laser-nuclear technologies.
Comments:
9 pages, 3 figures, submitted to the Proceedings of KVNO-2023
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2307.08711 [pdf]
3 citations
02
[Submitted on 18 Jul 2023]
Proton 0.01 MeV resonance width and low-energy $S$ -factor of p+10B fusion
A. M. Mukhamedzhanov
{\bf{Purpose}:} In this paper, the proton resonance width of the near-threshold resonance is calculated using two different approaches. The values of the proton width are used to calculate the low-energy $S$ -factor. \\ {\bf{Method:}} First, the proton resonance width is estimated using the mirror symmetry of the resonance $^{11} C (E_{x} = 8.70 MeV; \frac{5}{2}^{+})$ and the mirror bound state $^{11} B (E_{x} = 9.272 MeV; \frac{5}{2}^{+})$ . In the second approach, this width is estimated using the $R$ -matrix definition of the observable resonance width, which is expressed in terms of the $p -^{10} B$ resonant wave function calculated in the potential approach and the spectroscopic factor. \\ {\bf{Results}:} Depending on the method chosen, the calculated proton resonance width varies from $1.03 \times 1 0^{- 19}$ MeV to $2.96 \times 1 0^{- 19}$ MeV. The role of the near-threshold resonance is determined using fitting of two low-energy $S$ -factors from direct measurements [C. Angulo {\it et al.}, Z. Phys. A {\bf 345}, 333 (1993)] and from the indirect Trojan horse method (THM) [ A. Cvetinović {\it et al.}, Phys. Rev. C {\bf 97}, 065801 (2018)]. Within the framework of the $R$ -matrix method using the determined proton resonance widths and the modified THM parameters for six low-lying resonances, the low-energy $S$ -factors were calculated and compared with the corresponding experimental $S$ -factors. The closest agreement with the data is achieved with the proton resonance widths $1.0 \times 1 0^{- 19}$ MeV when fitting the $S$ -factor from the THM indirect measurements, and $1.68 \times 1 0^{- 19}$ MeV and $2.5 \times 1 0^{- 19}$ MeV when fitting the $S$ -factor from [Angulo {\it et al}, Z. Phys. A {\bf 345}, 333 (1993)].\
Comments:
11 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2307.08963 [pdf]
PRC(2023)·1 citation
03
[Submitted on 18 Jul 2023]
Postfission properties of uranium isotopes: A hybrid method with Langevin dynamics and the Hauser-Feshbach statistical model
Shyoya Tanaka · Nobuya Nishimura · Futoshi Minato · Yoshihiro Aritomo
Background: Precise understanding of nuclear fission is crucial for experimental and theoretical nuclear physics, astrophysics, and industrial applications; however, the complete physical mechanics is unresolved due to the complexities. Purpose: In this study, we present a new method to describe the dynamical-fission process and following prompt-neutron emission, where we combine the dynamical fission calculation based on the Langevin method and the Hauser-Feshbach statistical model. Methods: Two methods are connected smoothly within the universal charge distribution and the energy conservation, allowing us to calculate a sequence of fission dynamics and post-fission phase, including prompt neutron emission. Results: Using a certain set of model parameters, we successfully reproduce the experimental primary-fission yields, total kinetic energy, independent-fission yields, and prompt neutron emissions for the neutron induced fission of $^{236}$ U, a compound nucleus of $n +^{235} U$ . We elucidate the physical mechanism of the characteristic features observed in previous experiments, such as shell properties. Additionally, we apply our calculation to two very neutron-rich uranium isotopes, i.e., $^{250}$ U and $^{255}$ U, which are not experimentally confirmed but are important for r-process nucleosynthesis. Theoretical results indicate that $^{250}$ U exhibits an asymmetric multiple-peak fission yield distribution, while the neutron-rich $^{255}$ U has a single peak due to symmetric fission. Our method predicts post-neutron emission fragments, where $^{250}$ U shows a stronger neutron emissivity than $^{255}$ U. Conclusions: Our framework is highly reproducible in the experiments and shows that the number of emitted neutrons after fission differs significantly in neutron-rich uranium fission depending on distributions of fission variables.
Comments:
12 pages, 11 figures, published in PRC, minor revisions to match the final version
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
2307.08971 [pdf]
PRC(2023)·5 citations
04
[Submitted on 18 Jul 2023]
Effects of Symmetry Energy on the Equation of State for Hybrid Neutron Stars
Parada T. P. Hutauruk🇰🇷 · Hana Gil🇰🇷 · Seung-il Nam🇰🇷 · Chang Ho Hyun🇰🇷
In this paper, the implications of the symmetry energy on the hadron and quark phase transitions in the compact star, including the properties of the possible configurations of the quark-hadron hybrid stars, are investigated in the frameworks of the energy-density functional (EDF) models and the flavor SU(2) Nambu--Jona-Lasinio (NJL) model with the help of the Schwinger's covariant proper-time regularization (PTR) scheme. In this {theoretical setup}, the equations of states (EoSs) of hadronic matter for various values of symmetry energies obtained from the EDF models are employed to describe the hadronic matter, and the {flavor} SU(2) NJL model with various repulsive-vector interaction strengths are used to describe the quark matter. We then observe the obtained EoS in the mass-radius properties of the hybrid star configurations for various vector interactions and nuclear symmetry energies by solving the Tolman-Oppenheimer-Volkoff equation. We obtain that the critical density at which the phase transition occurs varies over the density (3.6--6.7) $ρ_{0}$ depending on the symmetry energy and the strength of the vector coupling $G_{v}$ . The maximum mass of the neutron star (NS) is susceptible to $G_{v}$ . When there is no repulsive force, the NS maximum mass is only about $1.5 M_{⊙}$ , but it becomes larger than $2.0 M_{⊙}$ when the vector coupling constant is about half of the {attractive} scalar coupling constant. Surprisingly, the presence of the quark matter does not affect the canonical mass of NS ( $1.4 M_{⊙}$ ), so observing the canonical mass of NSs can provide unique constraints to the EoS of hadronic matter at high densities.
Comments:
20 pages, 5 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2307.09038 [pdf]
J.Korean Phys.Soc.(2024)·6 citations
05
[Submitted on 18 Jul 2023]
Drag force near the QCD critical point
Yukinao Akamatsu🇯🇵 · Masayuki Asakawa🇯🇵
We discuss how heavy quark dynamics is affected by the critical fluctuations near the QCD critical point at finite temperature and density. We find that the heavy quark momentum diffusion constant scales as $κ \propto ξ^{z - 3 - η}$ . In the model H scenario, which is widely accepted for the critical dynamics, the exponents are known as $z ≃ 3, η \sim 0.04$ and the critical singularity of $κ$ is not significant if any. In the model B scenario, $z ≃ 4$ and $κ \propto ξ$ is singular near the critical point.
Comments:
4 pages, accepted in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2307.09049 [pdf]
PRC(2024)·1 citation
06
[Submitted on 18 Jul 2023]
Impact of nuclear structure on longitudinal flow decorrelations in high-energy isobar collisions
Maowu Nie🇨🇳 · Chunjian Zhang🇺🇸 · Zhenyu Chen🇨🇳 · Li Yi🇨🇳 · Jiangyong Jia🇺🇸
Fluctuations of harmonic flow along pseudorapidity, known as flow decorrelations, are an important probe of the initial state geometry of the quark-gluon plasma. The flow decorrelations are shown to be sensitive to the collective structure of the colliding nuclei, as revealed clearly by comparing collisions of isobars, $^{96}$ Ru+ $^{96}$ Ru and $^{96}$ Zr+ $^{96}$ Zr, which have different nuclear structures. The flow decorrelations in central collisions are mostly sensitive to nuclear deformations, while those in the mid-central collisions are primarily sensitive to differences in skin thickness between $^{96}$ Ru and $^{96}$ Zr. Longitudinal flow decorrelations in heavy-ion collisions are a new tool to probe the structure of colliding nuclei.
Comments:
It's almost the same as 2208.05416, i will simply replace the old one
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2307.09415 [pdf]
1 citation
07
[Submitted on 18 Jul 2023]
Influence of the tetraneutron on the EoS under core-collapse supernovae and heavy-ion collisions conditions
Helena Pais · Conrado Albertus · M. Ángeles Pérez-García · Constança Providência
Recently, a resonant state of four neutrons (tetraneutron) with an energy of $E_{4 n} = 2.37 \pm 0.38 (stat) \pm 0.44 (sys)$ MeV and a width of $Γ = 1.75 \pm 0.22 (stat) \pm 0.30 (sys)$ MeV was reported. In this work, we analyse the effect of including such an exotic state on the yields of other light clusters, that not only form in astrophysical sites, such as core-collapse supernovae and neutron star mergers, but also in heavy-ion collisions. To this aim, we use a relativistic mean-field formalism, where we consider in-medium effects in a two-fold way, via the couplings of the clusters to the mesons, and via a binding energy shift, to compute the low-density equation of state for nuclear matter at finite temperature and fixed proton fraction. We consider five light clusters, deuterons, tritons, heliums, $α$ -particles, and $^{6}$ He, immersed in a gas of protons and neutrons, and we calculate their abundances and chemical equilibrium constants with and without the tetraneutron. We also analyse how the associated energy of the tetraneutron would influence such results. We find that the low-temperature, neutron-rich systems, are the ones most affected by the presence of the tetraneutron, making neutron stars excellent environments for their formation. Moreover, its presence in strongly asymmetric matter may increase considerably the proton and the $α$ -particle fractions. This may have an influence on the dissolution of the accretion disk of the merger of two neutron stars.
Comments:
10 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2307.09418 [pdf]
Astron.Astrophys.(2023)·6 citations
08
[Submitted on 18 Jul 2023]
Study of $β^{-}$ decays for sd model space with Shell model
Surender Siwach
This paper investigates the beta decay of nuclei within the sd model space, encompassing the $0 d_{3/2}$ , $0 d_{5/2}$ , and $1 s_{1/2}$ shells. We comprehensively analyze their decay characteristics, including the half-life, $l o g f t$ value, Q value, branching ratio, B(GT) value, M(GT), and R(GT) value. These results are compared with experimental data from Z = 8-19 nuclei, employing the nuclear shell model framework. The calculations are performed using the USDB\cite{usdb} interaction, which is well-suited for nuclei with active valence nucleons in the $0 d_{3/2}$ , $0 d_{5/2}$ , and $1 s_{1/2}$ shells. The study offers valuable insights into the beta decay properties of these nuclei and contributes to our understanding of the nuclear shell structure.}
Comments:
23 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2307.09445 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE