Nuclear Theory·nucl-th

Wednesday·April 18, 2018

5 papers—4 primary·1 cross-listed

01
[Submitted on 17 Apr 2018]
Repulsive Four-Body Interactions of $α$ Particles and Quasi-Stable Nuclear $α$ -Particle Condensates in Heavy Self-Conjugate Nuclei
Dong Bai🇨🇳 · Zhongzhou Ren🇨🇳
We study the effects of repulsive four-body interactions of $α$ particles on nuclear $α$ -particle condensates in heavy self-conjugate nuclei using a semi-analytic approach, and find that the repulsive four-body interactions could decrease the critical number of $α$ particles, beyond which quasi-stable $α$ -particle condensate states can no longer exist, even if these four-body interactions make only tiny contributions to the total energy of the Hoyle-like state of $^{16}$ O. Explicitly, we study eight benchmark parameter sets, and find that the critical number $N_{cr}$ decreases by $∣Δ N_{cr} ∣ \sim 1 - 4$ from $N_{cr} \sim 11$ with vanishing four-body interactions. We also discuss the effects of four-body interactions on energies and radii of $α$ -particle condensates. Our study can be useful for future experiments to study $α$ -particle condensates in heavy self-conjugate nuclei. Also, the experimental determination of $N_{cr}$ will eventually help establish a better understanding on the $α$ -particle interactions, especially the four-body interactions.
Comments:
16 pages, 7 figures, accepted version
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1804.05992 [pdf]
PRC(2018)·9 citations
02
[Submitted on 17 Apr 2018]
Systematic study of $α$ decay of nuclei around $Z = 82$ , $N = 126$ shell closure within the cluster-formation model and proximity potential 1977 formalism
Jun-Gang Deng · Jie-Cheng Zhao · Peng-Cheng Chu · Xiao-Hua Li
In the present work, we systematically study the $α$ decay preformation factors $P_{α}$ within the cluster-formation model and $α$ decay half-lives by the proximity potential 1977 formalism for nuclei around $Z = 82$ , $N = 126$ closed shells. The calculations show that the realistic $P_{α}$ is linearly dependent on the product of valance protons (holes) and valance neutrons (holes) $N_{p} N_{n}$ . It is consistent with our previous works [X.-D. Sun \textit{et al.}, \href{https://journals.aps.org/prc/abstract/10.1103/PhysRevC.94.024338}{ Phys. Rev. C 94, 024338 (2016)}, J.-G. Deng \textit{et al.}, \href{https://journals.aps.org/prc/abstract/10.1103/PhysRevC.96.024318}{Phys. Rev. C 96, 024318 (2017)}], which $P_{α}$ are model-dependent and extracted from the ratios of calculated $α$ half-lives to experimental data. Combining with our previous works, we confirm that the valance proton-neutron interaction plays a key role in the $α$ preformation for nuclei around $Z = 82$ , $N = 126$ shell closures whether the $P_{α}$ is model-dependent or microcosmic. In addition, our calculated $α$ decay half-lives by using the proximity potential 1977 formalism taking $P_{α}$ evaluated by the cluster-formation model can well reproduce the experimental data and significantly reduce the errors.
Comments:
4 figures, 7 tables; Accepted by Physical Review C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1804.06010 [pdf]
PRC(2018)·64 citations
03
[Submitted on 17 Apr 2018]
Nuclear Equation of State from ground and collective excited state properties of nuclei
X. Roca-Maza🇮🇹 · N. Paar🇭🇷
This contribution reviews the present status on the available constraints to the nuclear equation of state (EoS) around saturation density from nuclear structure calculations on ground and collective excited state properties of atomic nuclei. It concentrates on predictions based on self-consistent mean-field calculations, which can be considered as an approximate realization of an exact energy density functional (EDF). EDFs are derived from effective interactions commonly fitted to nuclear masses, charge radii and, in many cases, also to pseudo-data such as nuclear matter properties. Although in a model dependent way, EDFs constitute nowadays a unique tool to reliably and consistently access bulk ground state and collective excited state properties of atomic nuclei along the nuclear chart as well as the EoS. For comparison, some emphasis is also given to the results obtained with the so called {\it ab initio} approaches that aim at describing the nuclear EoS based on interactions fitted to few-body data only. Bridging the existent gap between these two frameworks will be essential since it may allow to improve our understanding on the diverse phenomenology observed in nuclei. Examples on observations from astrophysical objects and processes sensitive to the nuclear EoS are also briefly discussed. As the main conclusion, the isospin dependence of the nuclear EoS around saturation density and, to a lesser extent, the nuclear matter incompressibility remain to be accurately determined. Experimental and theoretical efforts in finding and measuring observables specially sensitive to the EoS properties are of paramount importance, not only for low-energy nuclear physics but also for nuclear astrophysics applications.
Comments:
Progress in Particle and Nuclear Physics (accepted)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1804.06256 [pdf]
PPNP(2018)·259 citations
04
[Submitted on 17 Apr 2018]
Hyperheavy nuclei: existence and stability
A.V. Afanasjev · S.E.Agbemava · A. Gyawali
What are the limits of the existence of nuclei? What are the highest proton numbers $Z$ at which the nuclear landscape and periodic table of chemical elements cease to exist? These deceivably simple questions are difficult to answer especially in the region of hyperheavy ( $Z \geq 126$ ) nuclei. We present the covariant density functional study of different aspects of the existence and stability of hyperheavy nuclei. For the first time, we demonstrate the existence of three regions of spherical hyperheavy nuclei centered around ( $Z \sim 138, N \sim 230$ ), ( $Z \sim 156, N \sim 310$ ) and ( $Z \sim 174, N \sim 410$ ) which are expected to be reasonably stable against spontaneous fission. The triaxiality of the nuclei plays an extremely important role in the reduction of the stability of hyperheavy nuclei against fission. As a result, the boundaries of nuclear landscape in hyperheavy nuclei are defined by spontaneous fission and not by the particle emission as in lower $Z$ nuclei. Moreover, the current study suggests that only localized islands of stability can exist in hyperheavy nuclei.
Comments:
13 pages (including supplementary information), submitted to Physics Letters B, revised version of the manuscript with some additional information included
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1804.06395 [pdf]
PLB(2018)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE

Repulsive Four-Body Interactions of α Particles and Quasi-Stable Nuclear α-Particle Condensates in Heavy Self-Conjugate Nuclei

Systematic study of α decay of nuclei around Z=82, N=126 shell closure within the cluster-formation model and proximity potential 1977 formalism

Nuclear Equation of State from ground and collective excited state properties of nuclei

Hyperheavy nuclei: existence and stability

Affiliations

Repulsive Four-Body Interactions of $α$ Particles and Quasi-Stable Nuclear $α$ -Particle Condensates in Heavy Self-Conjugate Nuclei

Systematic study of $α$ decay of nuclei around $Z = 82$ , $N = 126$ shell closure within the cluster-formation model and proximity potential 1977 formalism