Nuclear Theory·nucl-th

Tuesday·May 23, 2017

10 papers—8 primary·2 cross-listed

01
[Submitted on 20 May 2017]
Time-dependent mean-field investigations of the quasifission process
A.S. Umar · C. Simenel · S. Ayik
We demonstrate that the microscopic Time-dependent Hartree-Fock (TDHF) theory provides an important approach to shed light on the nuclear dynamics leading to the formation of superheavy elements. In particular, we discuss studying quasifission dynamics and calculating ingredients for compound nucleus formation probability calculations. We also discuss possible extensions to TDHF to address the distribution of observables.
Comments:
Proceedings of a talk given at FUSION17, Hobart, Tasmania, AU (20-24 February, 2017)
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1705.07324 [pdf]
EPJ Web Conf.(2017)·0 citations
02
[Submitted on 20 May 2017]
Dispersion and decay of collective modes in neutron star cores
D. N. Kobyakov · C. J. Pethick · S. Reddy · A. Schwenk
We calculate the frequencies of collective modes of neutrons, protons and electrons in the outer core of neutron stars. The neutrons and protons are treated in a hydrodynamic approximation and the electrons are regarded as collisionless. The coupling of the nucleons to the electrons leads to Landau damping of the collective modes and to significant dispersion of the low-lying modes. We investigate the sensitivity of the mode frequencies to the strength of entrainment between neutrons and protons, which is not well characterized. The contribution of collective modes to the thermal conductivity is evaluated.
Comments:
10 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1705.07357 [pdf]
PRC(2017)·16 citations
03
[Submitted on 21 May 2017]
Multi-cluster dynamics in $_{Λ}^{13} C$ and analogy to clustering in $^{12} C$
Y. Funaki · M. Isaka · E. Hiyama · T. Yamada · K. Ikeda
We investigate structure of $_{Λ}^{13} C$ and discuss the difference and similarity between the structures of $^{12} C$ and $_{Λ}^{13} C$ by answering the questions if the linear-chain and gaslike cluster states, which are proposed to appear in $^{12} C$ , survives, or new structure states appear or not. We introduce a microscopic cluster model called, Hyper-Tohsaki-Horiuchi-Schuck-Röpke (H-THSR) wave function, which is an extended version of the THSR wave function so as to describe $Λ$ hypernuclei. We obtained two bound states and two resonance (quasi-bound) states for $J^{π} = 0^{+}$ in $_{Λ}^{13} C$ , corresponding to the four $0^{+}$ states in $^{12} C$ . However, the inversion of level ordering between the spectra of $^{12} C$ and $_{Λ}^{13} C$ , i.e. that the $0_{3}^{+}$ and $0_{4}^{+}$ states in $_{Λ}^{13} C$ correspond to the $0_{4}^{+}$ and $0_{3}^{+}$ states in $^{12} C$ , respectively, is shown to occur. The additional $Λ$ particle reduces sizes of the $0_{2}^{+}$ and $0_{3}^{+}$ states in $_{Λ}^{13} C$ very much, but the shrinkage of the $0_{4}^{+}$ state is only a half of the other states. In conclusion, the Hoyle state becomes quite a compact object with $_{Λ}^{9} Be + α$ configuration in $_{Λ}^{13} C$ and is no more gaslike state composed of the $3 α$ clusters. Instead, the $0_{4}^{+}$ state in $_{Λ}^{13} C$ , coming from the $^{12} C (0_{3}^{+})$ state, appears as a gaslike state composed of $α + α +_{Λ}^{5} He$ configuration, i.e. the Hoyle analog state. A linear-chain state in a $Λ$ hypernucleus is for the first time predicted to exist as the $0_{3}^{+}$ state in $_{Λ}^{13} C$ with more shrunk arrangement of the $3 α$ clusters along $z$ -axis than the $3 α$ linear-chain configuration realized in the $^{12} C (0_{4}^{+})$ state.
Comments:
9 pages, 6 figures, figures rearranged, accepted for publication in PLB
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1705.07394 [pdf]
PLB(2017)·22 citations
04
[Submitted on 21 May 2017]
An Empirical Scaling formula for fragments production in projectile fragmentation reactions
Yi-Dan Song · Chun-Wang Ma · Xue-Ying Liu · Hui-Ling Wei
A scaling phenomenon in the cross section for fragments has been found in the projectile fragmentation reaction, and an empirical scaling formula is proposed by considering the dependence of cross section on the size and asymmetry of the reaction system and the fragment itself. Furthermore, the empirical scaling formula is used to predict the production of fragment in the $^{68}$ Ni/ $^{69}$ Cu/ $^{72}$ Zn + $^{9}$ Be reactions around 90 $A$ MeV. Compared to the results calculated by the statistical abrasion ablation model and the {\sc epax3} parameterizations, the empirical scaling formula can better reproduce the measured fragments. The empirical scaling formula can be used to predict the yield for fragment in projectile fragmentation reaction.
Comments:
7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1705.07415 [pdf]
1 citation
05
[Submitted on 22 May 2017]
$K^{+}$ -nucleus elastic scattering revisited from perspective of partial restoration of chiral symmetry
Kenji Aoki🇯🇵 · Daisuke Jido🇯🇵
The $K^{+}$ meson properties in the nuclear medium are investigated by considering the wavefunction renormalization as a first step to reveal the in-medium properties of the $K^{+}$ meson in the context of partial restoration of chiral symmetry. The $K^{+} N$ elastic scattering amplitude is constructed using chiral perturbation theory up to the next-to-leading order. Using the constructed amplitude, we calculate the wavefunction renormalization in the Thomas-Fermi approximation. We obtained a good description of the $K^{+} N$ elastic scattering amplitude. The obtained wavefunction renormalization factor suggests the 2 to 6% enhancement of the $K^{+} N$ interaction at the saturation density. We conclude that the wavefunction renormalization could be one of the important medium effects for the $K^{+}$ meson.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1705.07548 [pdf]
PTEP(2017)·9 citations
06
[Submitted on 22 May 2017]
Pairing in spherical nuclei: quasi-particle random phase approximation calculations with the Gogny interaction
V. De Donno · G. Co' · M. Anguiano · A. M. Lallena
We investigate the effects of the pairing in spherical nuclei. We use the same finite-range interaction of Gogny type in the three steps of our approach, Hartree-Fock, Bardeen, Cooper and Schrieffer, and quasi-particle random phase approximation calculations. We study electric and magnetic dipole, quadrupole and octuple excitations in oxygen and calcium isotopes and also in isotopes with 20 neutrons. We investigate the pairing effects on single particle energies and occupation probabilities, on the excitation energies, $B$ -values and collectivity of low-lying states including the isoscalar electric dipole and the magnetic dipole excitations, and also the giant resonances. The inclusion of the pairing increases the values of the excitation energies in all the cases we have studied. In general, the effects of the pairing are too small to remarkably improve the agreement with the available experimental data.
Comments:
18 pages, 6 tables, 8 figures, accepted for publication in Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1705.07602 [pdf]
PRC(2017)·7 citations
07
[Submitted on 22 May 2017]
Toward a complete theory for predicting inclusive deuteron breakup away from stability
G. Potel · G. Perdikakis · B. V. Carlson · M. C. Atkinson · P. Capel · W. H. Dickhoff · J. E. Escher · M. S. Hussein · J. Lei · W. Li · A. O. Macchiavelli · A. M. Moro and 3 other authors
We present an account of the current status of the theoretical treatment of inclusive $(d, p)$ reactions in the breakup-fusion formalism, pointing to some applications and making the connection with current experimental capabilities. Three independent implementations of the reaction formalism have been recently developed, making use of different numerical strategies. The codes also originally relied on two different but equivalent representations, namely the prior (Udagawa-Tamura, UT) and the post (Ichimura-Austern-Vincent, IAV) representations. The different implementations have been benchmarked, and then applied to the Ca isotopic chain. The neutron-Ca propagator is described in the Dispersive Optical Model (DOM) framework, and the interplay between elastic breakup (EB) and non-elastic breakup (NEB) is studied for three Ca isotopes at two different bombarding energies. The accuracy of the description of different reaction observables is assessed by comparing with experimental data of $(d, p)$ on $^{40, 48}$ Ca. We discuss the predictions of the model for the extreme case of an isotope ( $^{60}$ Ca) currently unavailable experimentally, though possibly available in future facilities (nominally within production reach at FRIB). We explore the use of $(d, p)$ reactions as surrogates for $(n, γ)$ processes, by using the formalism to describe the compound nucleus formation in a $(d, p γ)$ reaction as a function of excitation energy, spin, and parity. The subsequent decay is then computed within a Hauser-Feshbach formalism. Comparisons between the $(d, p γ)$ and $(n, γ)$ induced gamma decay spectra are discussed to inform efforts to infer neutron captures from $(d, p γ)$ reactions. Finally, we identify areas of opportunity for future developments, and discuss a possible path toward a predictive reaction theory.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1705.07782 [pdf]
EPJA(2017)·80 citations
08
[Submitted on 22 May 2017]
Effect of an electromagnetic field on the spectra and elliptic flow of particles
Bohao Feng🇨🇳 · Zeyan Wang🇨🇳
In 2+1 dimensions, the evolution of flow under the influence of an external electromagnetic field is simulated. The external electromagnetic field is exponentially decaying with time. Under the same initial conditions, flow evolution with and without the external electromagnetic field is compared. It was found that the production of particles was enhanced when the external electromagnetic field was present. As the strength of the electromagnetic field increased, more particles were produced. Enhancement is greater at the high transverse momentum than at the low transverse momentum. In addition, the electromagnetic field also modifies the elliptic flow and the modification is related to the mass and charge of the particles.
Comments:
6 pages,4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1705.07842 [pdf]
PRC(2017)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE