Deformation of 1p shells in (2s, 1d) shell nuclei from a systematic study of (, τ) reactions

Mairle, G.; Wagner, Gerhard; Knöpfle, K. T.; Pao, Liu Ken; Riedesel, H.; Bechtold, V.; Friedrich, L.

doi:10.1016/0375-9474(81)90266-9

Cited by 27 publications

(4 citation statements)

References 29 publications

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“…2 36 S, and 38 Ar have spherical shape. In contrast, neutron-rich nuclei 30 Ne and 32 Mg have large deformation in spite of N = 20 isotones. This indicates the disappearance of the magic number N = 20 in these neutron-rich nuclei.…”

Section: Experimental Evidencementioning

confidence: 91%

“…(3) for stripping and pick-up reactions, respectively. The definition (4) has been used in an experimental determination of single-particle energies [29] where the single-particle energies for open-shell nuclei 20,22 Ne are determined from the experimental data of the stripping (d, n) [29] and pick-up (d, 3 He) [30][31][32] reactions on 20,22 Ne nuclei.…”

Section: Single-particle Energymentioning

confidence: 99%

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Single-particle energies in neutron-rich nuclei by shell model sum rule

Umeya

Muto

2006

Phys. Rev. C

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One of the most striking features in neutron-rich nuclei is the disappearance of magic number N = 8 or 20, which indicates a change of single-particle energy spectra and the disappearance of a large energy gap at the magic number. A sum-rule method is formulated, based on the shell model, for the evaluation of single-particle energies. It is shown that the triplet-even central component of the NN interaction plays a decisive role through the monopole interaction for a change of single-particle energy spectra, leading to a rapid decrease of the energy gap at N = 8 and 20. The triplet-even attraction is due partly to the original central interaction and partly to the second-order tensor correlations of the one-pion exchange potential. A multipole expansion analysis of NN interactions shows that the contribution to the single-particle energy from the monopole interactions between two orbits depends on the nodal quantum numbers of the orbits.

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Section: Experimental Evidencementioning

confidence: 91%

Section: Single-particle Energymentioning

confidence: 99%

Single-particle energies in neutron-rich nuclei by shell model sum rule

Umeya

Muto

2006

Phys. Rev. C

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“…However, there are several possible candidates are reported. The proton hole 1/2 − states in 19 F and 21 F are well identified at 0.1 and 1.1 MeV, respectively [219,220]. By several experiments, the candidates of the 1/2 − states are reported at 3.4 MeV in 23 F [221, 222] and 4.2 MeV in 25 F [223,224].…”

Section: (C) and (D))mentioning

confidence: 99%

Antisymmetrized molecular dynamics studies for exotic clustering phenomena in neutron-rich nuclei

Kimura¹,

Suhara²,

Kanada-En’yo³

2016

Eur. Phys. J. A

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We present a review of recent works on clustering phenomena in unstable nuclei studied by antisymmetrized molecular dynamics (AMD). The AMD studies in these decades have uncovered novel types of clustering phenomena brought about by the excess neutrons. Among them, this review focuses on the molecule-like structure of unstable nuclei.One of the earliest discussions on the clustering in unstable nuclei was made for neutron-rich Be and B isotopes. AMD calculations predicted that the ground state clustering is enhanced or reduced depending on the number of excess neutrons. Today, the experiments are confirming this prediction as the change of the proton radii. Behind this enhancement and reduction of the clustering, there are underlying shell effects called molecular-and atomic-orbits. These orbits form covalent and ionic bonding of the clusters analogous to the atomic molecules. It was found that this "molecular-orbit picture" reasonably explains the low-lying spectra of Be isotopes. The molecular-orbit picture is extended to other systems having parity asymmetric cluster cores and to the three cluster systems. O and Ne isotopes are the candidates of the former, while the 3α linear chains in C isotopes are the latter. For both subjects, many intensive studies are now in progress.We also pay a special attention to the observables which are the fingerprint of the clustering. In particular, we focus on the monopole and dipole transitions which are recently regarded as good probe for the clustering. We discuss how they have and will reveal the exotic clustering.where X denotes Z i , ν or χ i . λ and µ are arbitrary numbers, but µ must have negative sign. The energy of the system H is defined as (8) As time t being evolved by the Eq. (7), the energy of the system is decreased and we obtain the set of parameters which minimizes the energy of the system. The calculation which employs the eigenstate of the parity Φ π to evaluate the energy is called variation before angular momentum projection (VBP), while the calculation employing the eigenstate of parity and angular momentum Φ Jπ M K is called variation after angular momentum projection (VAP) [42]. In the case of VBP, the angular momentum projection is performed after the energy minimization.To obtain the wave functions which have the configurations different from the energy minimum, the constrained energy minimization is often performed in VBP calculations. For example, the constraint on the quadrupole deformation parameter β is imposed by adding the constraint potential to the energy asHere, the magnitude of constraint potential v β is chosen large enough so that the deformation parameter β of the wave function approximately equals to β 0 after the energy minimization.Another way to obtain the excited configurations is orthogonalization method [42] that is used in VAP calculatons in which the variational wave function is orthogonalized to the energy minimum state By applying this procedure successively, the second, third and more excited configurations are obtained. He...

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“…AMD+GCM calculation (Fig. 3(b)) shows that the ground state is strongly deformed, which is comparable with neighboring nuclei such as 32 Mg, and has an almost pure 2p3h configuration in which two neutrons are promoted into pf shell across N = 20 shell gap. The calculated magnetic moment of the ground state is −0.91μ N , while the observed value is −0.88μ N .…”

Section: Coexistence Of Spherical and Deformed States And Neutron Ormentioning

confidence: 77%

Clustering Aspects of Highly Excited States and Neutron-Rich Nuclei

Kimura

Furutachi

Taniguchi

et al. 2012

Prog. Theor. Phys. Suppl.

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Recent researches of clustering aspects in stable and unstable nuclei based on antisymmetrized molecular dynamics (AMD) are reported. We will focus on the clustering of highly excited states of 24 Mg, the low-lying spectroscopy and novel exotic clustering in the vicinity of the island of inversion. §1. IntroductionClustering aspect is one of the most important ingredients of the nuclear manybody problem. It embodies the dynamical aspects of nuclear system, namely assembling and disassembling of nucleons, which make nuclear physics challenging and fascinating problem. Owing to the theoretical and experimental developments, the domain of the cluster studies is rapidly expanding toward highly excited and neutron-rich nuclei. For example, the studies of unstable nuclei have revealed novel types of clustering represented by Be isotopes, 1)-3) and analogous structures have been discussed in heavier system. 4), 5) The intensive discussions on the nα gas-like state in 12 C 6) and 16 O 7) renewed our interest in the clustering of the highly excited states. Theoretical and experimental studies are rapidly developing toward heavier systems.AMD has been one of powerful theoretical approaches to investigate those clustering aspects in the highly excited states and in the neutron-rich nuclei. In this article, we report some of recent activities of AMD studies for clustering of stable and unstable nuclei. The dominance of the cluster states around the threshold energies despite of the mean-field nature of the low-lying states is remarked using 24 Mg 8) as an illustrative example ( §3). AMD has achieved sufficient accuracy and predictive power for the study of the low-lying mean-field dynamics in heavier unstable nuclei. It enabled us to discuss and predict the coexistence of the spherical and deformed states 9) and neutron-halo structure 10), 11) in the island of inversion ( §4). Clustering will also play an important role in the vicinity of the island of inversion. We predict the coexistence of the mean-field states and the novel types of clustering which are composed of clusters and many valence neutrons at small excitation energies in F isotopes far from stability. 12)

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Deformation of 1p shells in (2s, 1d) shell nuclei from a systematic study of (, τ) reactions

Cited by 27 publications

References 29 publications

Single-particle energies in neutron-rich nuclei by shell model sum rule

Single-particle energies in neutron-rich nuclei by shell model sum rule

Antisymmetrized molecular dynamics studies for exotic clustering phenomena in neutron-rich nuclei

Clustering Aspects of Highly Excited States and Neutron-Rich Nuclei

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