Nuclear Theory·nucl-th

Tuesday·March 17, 2015

9 papers—5 primary·4 cross-listed

01
[Submitted on 14 Mar 2015]
Alpha cluster structures and monopole excitations in $^{13}$ C
Taiichi Yamada · Yasuro Funaki
The structure of $1/ 2^{\pm}$ states in $^{13}$ C up to around the $3 α + n$ threshold ( $E_{x} = 12.3$ ~MeV) is investigated with a full four-body $3 α + n$ orthogonality condition model (OCM) calculation, where the $3 α$ OCM, the model space of which is the subspace of the $3 α + n$ model, describes well the structure of the low-lying states of $^{12}$ C including the $2_{2}^{+}$ , $0_{3}^{+}$ , and $0_{4}^{+}$ states, which have been recently observed above the Hoyle state ( $0_{2}^{+}$ ). A full spectrum up to the $1/ 2_{5}^{-}$ ( $1/ 2_{3}^{+}$ ) state is reproduced consistently with the lowest five $1/ 2^{-}$ (three $1/ 2^{+}$ ) states of experimental spectrum. It is shown that the $1/ 2_{2}^{-}$ and $1/ 2_{3}^{-}$ states are characterized by the dominant cluster configurations of $^{9}$ Be( $3/ 2^{-}$ , $1/ 2^{-}$ )+ $α$ , while the ground state $1/ 2_{1}^{-}$ has a shell-model-like structure. The observed monopole transition strengths to the $1/ 2_{2, 3}^{-}$ states are consistently reproduced for the first time. These results indicate that the excited $1/ 2^{-}$ states have cluster structures. They are compared to those by the previous work with the shell model. On the other hand, the $1/ 2_{1}^{+}$ state is found to have a loosely bound neutron structure in which the extra neutron moves around $^{12}$ C(g.s) core with $1 S$ orbit, reflecting the fact that this state appears by $1.9$ MeV just below the $^{12}$ C(g.s)+ $n$ threshold, while the $1/ 2_{2}^{+}$ and $1/ 2_{3}^{+}$ states are characterized by $^{9}$ Be+ $α$ structures. We found that the $1/ 2_{5}^{+}$ state located above the $3 α + n$ threshold is the Hoyle analogue state in $^{13}$ C, the wave function of which is described by product states of constituent clusters, $(0 S)_{α}^{3} (S)_{n}$ , with the probability of $52$ %.
Comments:
39 pages, 9 figures, version accepted for publication in Physical Review C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1503.04261 [pdf]
PRC(2015)·56 citations
02
[Submitted on 14 Mar 2015]
Spectrum of resonance states in $^{6}$ He. Experimental and theoretical analysis
O. M. Povoroznyk · V. S. Vasilevsky
We explore the structure of resonance states in $^{6}$ He by experimental and theoretical methods. We present the results of experimental investigations of the three-body continuous spectrum of $^{6}$ He. For this aim, we use the reaction $^{3}$ H $(α, p α) nn$ , which is induced by the interaction of alpha-particles with a triton at the beam energy $E_{α} =$ ~67.2 MeV. The theoretical analysis of the resonance structure in $^{6}$ He is carried out within the framework of a three-cluster microscopic model. The model exploits the hyperspherical harmonics to describe the intercluster dynamics. The set of new resonance states is discovered by the experimental and theoretical methods. The energy, width, and dominant decay channels of resonances are determined.The obtained results are compared in detail with the results of different theoretical models and experiments as well.
Comments:
16 pp, 17 figures, UJP style file provided
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1503.04308 [pdf]
Ukr.J.Phys.(2015)·4 citations
03
[Submitted on 15 Mar 2015]
Production of heavy neutron-rich nuclei in transfer reactions within the dinuclear system model
Long Zhu🇨🇳 · Zhao-Qing Feng🇨🇳 · Feng-Shou Zhang🇨🇳
The dynamics of nucleon transfer processes in heavy-ion collisions is investigated within the dinuclear system model. The production cross sections of nuclei in the reactions $^{136}$ Xe+ $^{208}$ Pb and $^{238}$ U+ $^{248}$ Cm are calculated and the calculations are in good agreement with the experimental data. The transfer cross sections for the $^{58}$ Ni+ $^{208}$ Pb reaction are calculated and compared with the experimental data. We predict the production cross sections of neutron-rich nuclei $^{165 - 168}$ Eu, $^{169 - 173}$ Tb, $^{173 - 178}$ Ho, and $^{181 - 185}$ Yb based on the reaction $^{176}$ Yb+ $^{238}$ U. It can be seen that the production cross sections of the neutron-rich nuclei $^{165}$ Eu, $^{169}$ Tb, $^{173}$ Ho, and $^{181}$ Yb are 2.84 $μ$ b, 6.90 $μ$ b, 46.24 $μ$ b, and 53.61 $μ$ b, respectively, which could be synthesized in experiment.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1503.04421 [pdf]
J.Phys.G(2015)·49 citations
04
[Submitted on 15 Mar 2015]
Enhancement of the CP-odd effect in the nuclear electric dipole moment of $^{6}$ Li
Nodoka Yamanaka🇯🇵 · Emiko Hiyama🇯🇵
We calculate for the first time the electric dipole moment (EDM) of the $^{6}$ Li nucleus within the alpha + p + n three-body cluster model using the Gaussian expansion method, assuming the one meson exchange P, CP-odd nuclear forces. It is found that the EDM of the $^{6}$ Li is 2 times more sensitive on the isovector pion exchange P, CP-odd nuclear force than the deuteron EDM, due to the CP-odd interaction between the nucleons and the alpha cluster. The $^{9}$ Be EDM is also calculated in the same framework as an alpha + alpha + n three-body system. We also test the ab initio calculation of the EDM of the deuteron, $^{3}$ H and $^{3}$ He nuclei using the realistic Argonne $v 18$ nuclear force. In the ab initio calculations, good agreements with previous studies are obtained. We finally discuss the prospects for the new physics beyond the standard model.
Comments:
6 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1503.04446 [pdf]
PRC(2015)·59 citations
05
[Submitted on 16 Mar 2015]
Search for octupole correlations in $^{147}$ Nd
E. Ruchowska · H. Mach · M. Kowal · J. Skalski · W. A. Plociennik · B. Fogelberg
Properties of excited states in $^{147}$ Nd have been studied with multispectra and $γ γ$ coincidence measurements. Twenty-four new $γ$ -lines and three new levels have been introduced into the level scheme of $^{147}$ Nd. Lifetimes of eight excited levels in $^{147}$ Nd, populated in the $β$ decay of $^{147}$ Pr, have been measured using the advanced time-delayed $β γ γ$ (t) method. Reduced transition probabilities have been determined for 30 $γ$ -transitions in $^{147}$ Nd. Potential energy surfaces on the ( $β_{2}$ , $β_{3}$ ) plane calculated for $^{147}$ Nd using the Strutinsky method predict two single quasiparticle configurations with nonzero octupole deformation, with K=1/2 and K=5/2. We do not observe parity doublet bands with K=5/2. For pair of opposite parity bands that could form the K=1/2 parity doublet we were able only to determine lower limit of the dipole moment, $∣ D_{0} ∣ \geq$ 0.02 e $\cdot f m$ .
Comments:
Submitted to PRC
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1503.04606 [pdf]
PRC(2015)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Alpha cluster structures and monopole excitations in 13C

Spectrum of resonance states in 6He. Experimental and theoretical analysis

Production of heavy neutron-rich nuclei in transfer reactions within the dinuclear system model

Enhancement of the CP-odd effect in the nuclear electric dipole moment of 6Li

Search for octupole correlations in 147Nd

Affiliations

Alpha cluster structures and monopole excitations in $^{13}$ C

Spectrum of resonance states in $^{6}$ He. Experimental and theoretical analysis

Enhancement of the CP-odd effect in the nuclear electric dipole moment of $^{6}$ Li

Search for octupole correlations in $^{147}$ Nd