Shell-model study for neutron-rich<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="italic">sd</mml:mi></mml:mrow></mml:math>-shell nuclei

Kaneko, Kazunari; Sun, Yang; Mizusaki, T.; Hasegawa, M.

doi:10.1103/physrevc.83.014320

Cited by 75 publications

(64 citation statements)

References 42 publications

(89 reference statements)

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“…It has been demonstrated that despite of its simplicity, this EPQQM model works surprisingly well for different mass regions, for example, the proton-rich p f shell [10] and the p f 5/2 g 9/2 shell [11], the neutron-rich f pg shell [12], and the sd-p f shell region [13]. It has also been successfully applied to the neutron-rich nuclei around 132 Sn [14,15].…”

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confidence: 99%

Toward a unified realistic shell-model Hamiltonian with the monopole-based universal force

et al. 2014

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We propose a unified realistic shell-model Hamiltonian employing the pairing plus multipole Hamiltonian combined with the monopole interaction constructed starting from the monopole-based universal force by Otsuka et al. (Phys. Rev. Lett. 104, 012501 (2010)). It is demonstrated that the proposed PMMU model can consistently describe a large amount of spectroscopic data as well as binding energies in the p f and p f 5/2 g 9/2 shell spaces, and could serve as a practical shell model for even heavier mass regions. PACS numbers: 21.30.Fe, 21.60.Cs, 21.10.Dr, 27.50.+e The nuclear shell-model interaction can in principle be derived microscopically from the free nucleon-nucleon force. In fact, such attempts were made in the early years for the beginning of the shell [1,2]. However, it was soon after realized that such an interaction fail to describe binding energies, excitation spectra, and transitions if many valence nucleons were considered. To reproduce experimental data, considerable efforts have been put forward to construct the so-called effective interactions, such as USD [3] and USDA/B [4] for the sd shell, KB3G [5] and GXPF1A [6] for the p f shell, and JUN45 [7] and jj4b [8] for the p f 5/2 g 9/2 model space. Each of these interactions is applicable to a given model space while mutual relations among them are obscure. On the other hand, it has been shown [9] that realistic effective interactions are dominated by the pairing plus quadrupole-quadrupole (P + QQ) terms with the monopole interaction. This finding not only makes the understanding of effective interactions in nuclei intuitive, but may also be used to unify effective interactions for different model spaces. In particular, one may begin to talk about universality for shell models.Along the lines of this thought, we have carried out shellmodel calculations using the extended P + QQ Hamiltonian combined with the monopole terms (EPQQM), which are regarded as corrections for the average monopole interaction. It has been demonstrated that despite of its simplicity, this EPQQM model works surprisingly well for different mass regions, for example, the proton-rich p f shell [10] and the p f 5/2 g 9/2 shell [11], the neutron-rich f pg shell [12], and the sd-p f shell region [13]. It has also been successfully applied to the neutron-rich nuclei around 132 Sn [14,15]. However, these calculations rely heavily on phenomenological adjustments on the monopole corrections. Consequently, the EPQQM model cannot describe binding energies or unusual structures such as the first excited 0 + state of Zn and Ge isotopes around N = 40 [16], and it essentially provides no information about the unconventional shell evolution in neutronrich nuclei.The monopole interaction is a crucial ingredient for successful shell-model calculations. It is defined as [17]where V JT ab,ab are the interaction matrix elements. The connection between the monopole interaction and the tensor force [18] was confirmed, which explains the shell evolution [19]. It was shown [20,21] shown by open and ...

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Toward a unified realistic shell-model Hamiltonian with the monopole-based universal force

et al. 2014

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“…The erosion of the shell gap and the migration of neutron magic numbers such as N = 8 [1] and 20 [2] far from stability have been important and fascinating subjects in nuclear structure physics [3]. The N = 28 shell closure in neutron-rich Si and S isotopes has received considerable experimental [4][5][6][7][8][9][10][11][12][13] and theoretical attention [14][15][16][17][18][19][20][21][22][23]. Experimental data [5,6,[8][9][10][11] indicate gradual quenching of the N = 28 shell gap toward neutron-rich isotones and the onset of deformation in N ≈ 28 S and Si isotopes.…”

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Prolate, oblate, and triaxial shape coexistence, and the lost magicity ofN=28in43S

et al. 2013

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We report the low-lying spectrum and collective β and γ deformation of 43 S as investigated by antisymmetrized molecular dynamics. Our result successfully explains the observed data including an isomeric 7/2 − 1 state and illustrates the coexistence of the prolate-deformed ground band with a vanishing N = 28 shell gap, a triaxially deformed isomeric state, and an oblate-deformed excited band at very low excitation energies. The erosion of the shell gap and the migration of neutron magic numbers such as N = 8 [1] and 20 [2] far from stability have been important and fascinating subjects in nuclear structure physics [3]. The N = 28 shell closure in neutron-rich Si and S isotopes has received considerable experimental [4][5][6][7][8][9][10][11][12][13] and theoretical attention [14][15][16][17][18][19][20][21][22][23]. Experimental data [5,6,[8][9][10][11] indicate gradual quenching of the N = 28 shell gap toward neutron-rich isotones and the onset of deformation in N ≈ 28 S and Si isotopes. Unlike the case of smaller magic numbers, the neutron single-particle levels f 7/2 and p 3/2 that compose the N = 28 shell gap belong to the same major shell in the absence of spin-orbit splitting, and their angular momentum differs by 2. Therefore, we can expect that quenching of the N = 28 shell gap induces strong quadrupole correlations, which will lead to the coexistence of various deformed states [24]. For example, observation of low-lying states [25] and theoretical calculations [22,23] suggest shape coexistence in 44 S. In the vicinity of 44 S, 43 S is of particular importance and interest for the following reasons. First, 43 S has an odd number of neutrons. Thus, its low-lying spectrum provides direct information on the neutron single-particle levels. Second, and more importantly, it is believed to have a prolate-deformed ground state and a very low-lying isomeric 7/2 − 1 state at 319 keV, which has been interpreted in the shell model framework as resulting from an inversion of the normal (νf 7/2 ) −1 and deformed intruder (νp 3/2 ) 1 configurations [12]. More recently, measurement of the electric quadrupole moment of the 7/2 − 1 state [26] has shown that it deviates from the pure spherical (νf 7/2 ) −1 configuration, suggesting possible shape coexistence driven by quenching of the N = 28 shell gap and the resulting strong quadrupole correlation. Therefore, a theoretical calculation that can describe the quadrupole collectivity in a large model space is essential for revealing the nature of this shape coexistence far from stability.In this Rapid Communication, we report triaxial deformation of the isomeric 7/2 − 1 state and the shape coexistence of prolate, triaxial, and oblate deformation of 43 S at excitation energies of less than 2 MeV. We apply the antisymmetrized molecular dynamics (AMD), which has already been successfully applied to the breaking of neutron magic number N = 8 [27][28][29] and 20 [30][31][32], combined with the generator coordinate method (GCM) using generator coordinates of the quadrupole deforma...

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“…The nuclear valence-space shell model is one of the work horses in nuclear structure theory. It is very successful for the description of spectra and spectroscopic observables over a large range of nuclei and plays an important role in guiding and interpreting experiments from stable to exotic nuclei [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Two critical aspects in the application of the shell model (SM) are the construction of the effective valence-space interaction as well as corresponding effective operators and the solution of the eigenvalue problem in the model space of the valence nucleons.…”

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Importance-truncated large-scale shell model

2016

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We propose an importance-truncation scheme for the large-scale nuclear shell model that extends its range of applicability to larger valence spaces and mid-shell nuclei. It is based on a perturbative measure for the importance of individual basis states that acts as an additional truncation for the many-body model space in which the eigenvalue problem of the Hamiltonian is solved numerically. Through a posteriori extrapolations of all observables to vanishing importance threshold, the full shell-model results can be recovered. In addition to simple threshold extrapolations, we explore extrapolations based on the energy variance. We apply the importancetruncated shell model for the study of 56 Ni in the p f valence space and of 60 Zn and 64 Ge in the p f g9 /2 space. We demonstrate the efficiency and accuracy of the approach, which pave the way for future shell-model calculations in larger valence spaces with valence-space interactions derived in ab initio approaches.PACS numbers: 21.60. Cs, 27.50.+e Introduction. The nuclear valence-space shell model is one of the work horses in nuclear structure theory. It is very successful for the description of spectra and spectroscopic observables over a large range of nuclei and plays an important role in guiding and interpreting experiments from stable to exotic nuclei [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Two critical aspects in the application of the shell model (SM) are the construction of the effective valence-space interaction as well as corresponding effective operators and the solution of the eigenvalue problem in the model space of the valence nucleons.

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Shell-model study for neutron-richsd-shell nuclei

Cited by 75 publications

References 42 publications

Toward a unified realistic shell-model Hamiltonian with the monopole-based universal force

Toward a unified realistic shell-model Hamiltonian with the monopole-based universal force

Prolate, oblate, and triaxial shape coexistence, and the lost magicity ofN=28in43S

Importance-truncated large-scale shell model

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