Nuclear Theory·nucl-th

Friday·December 25, 2020

6 papers—3 primary·3 cross-listed

01
[Submitted on 24 Dec 2020]
Tensor-force effects on shell-structure evolution in $N = 82$ isotones and $Z = 50$ isotopes in the relativistic Hartree-Fock theory
Zhiheng Wang · Tomoya Naito · Haozhao Liang
The evolution of the energy difference between the neutron states $1 i_{13/2}$ and $1 h_{9/2}$ in the $N = 82$ isotones and that between the proton states $1 h_{11/2}$ and $1 g_{7/2}$ in the $Z = 50$ isotopes are investigated within the framework of the relativistic Hartree-Fock theory, using the density-dependent effective interactions PKA1 and PKO $i$ ( $i = 1$ , $2$ , $3$ ). By identifying the contributions of the tensor force, which is naturally induced via the Fock terms, we find that the tensor force plays crucial roles in the evolution of the shell structure. The strength of the tensor force is also explored. It is found that moderately increasing the coupling strength of pion-nucleon coupling, i.e., $f_{π}$ , will significantly improve the description of the shell-structure evolution. In particular, reducing the density dependence of $f_{π}$ is shown to be more preferable, in comparison to enlarging $f_{π}$ with a factor. This is in consistence with the idea of "tensor renormalization persistency" and provides valuable guidance for the development of nuclear energy density functional in the relativistic framework.
Comments:
15 pages, 7 figures, 3 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2012.13143 [pdf]
PRC(2021)·9 citations
02
[Submitted on 24 Dec 2020]
Kinetic Energy Distribution of Fragments for Thermal Neutron-Induced $^{235}$ U and $^{239}$ Pu Fission Reactions
Xiaojun Sun · Haiyuan Peng · Liying Xie · Kai Zhang · Yan Liang · Yinlu Han · Nengchuan Su · Jie Yan · Jun Xiao · Junjie Sun
Focused on the generation and evolution of vast complementary pairs of the primary fission fragments at scission moment, Dinuclear and Statistical Model (DSM) is proposed. (1) It is assumed that the fissile nucleus elongates along a symmetric coaxis until it breaks into two primary fission fragments. (2) Every complementary pair of the primary fission fragments is approximatively described as two ellipsoids with large deformation at scission moment. (3) The kinetic energy in every complementary pair of the primary fragments is mainly provided by Coulomb repulsion, which is explicitly expressed through strict six-dimensional integrals. (4) Only three phenomenological coefficients are obtained to globally describe the quadrupole deformation parameters of arbitrary primary fragments both for $^{235}$ U( $n_{t h}, f$ ) and $^{239}$ Pu( $n_{t h}, f$ ) reactions, on the basis of the common characteristics of the measured data, such as mass and charge distributions, kinetic energy distributions. In the framework of DSM, the explicit average total kinetic energy distribution $T K E (A)$ and the average kinetic energy distribution $K E (A)$ are consistently represented. The theoretical results in this paper agree well with the experimental data. Furthermore, this model is expected as the reliable approach to generally evaluate the corresponding observebles for thermal neutron-induced fission of actinides.
Comments:
13pages, 12 figures, 6 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2012.13281 [pdf]
1 citation
03
[Submitted on 24 Dec 2020]
19B isotope as a 17B-n-n three-body cluster close to unitary limit
J. Carbonell🇫🇷 · E. Hiyama🇯🇵 · R. Lazauskas🇫🇷 · F. M. Marqués🇫🇷
We describe 19B in terms of a 17B-n-n three-body system, where the two-body subsystems 17B-n and n-n are unbound (virtual) states close to the unitary limit. The energy of 19B ground state is well reproduced and two low-lying resonances are predicted. Their eventual link with the Efimov physics is discussed. This model can be extended to describe the recently discovered resonant states in 20,21B.
Comments:
27th International Nuclear Physics Conference (INPC2019). arXiv admin note: substantial text overlap with arXiv:1912.05427
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2012.13342 [pdf]
J.Phys.Conf.Ser.(2020)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Tensor-force effects on shell-structure evolution in N=82 isotones and Z=50 isotopes in the relativistic Hartree-Fock theory

Kinetic Energy Distribution of Fragments for Thermal Neutron-Induced 235U and 239Pu Fission Reactions

19B isotope as a 17B-n-n three-body cluster close to unitary limit

Affiliations

Tensor-force effects on shell-structure evolution in $N = 82$ isotones and $Z = 50$ isotopes in the relativistic Hartree-Fock theory

Kinetic Energy Distribution of Fragments for Thermal Neutron-Induced $^{235}$ U and $^{239}$ Pu Fission Reactions