Multiparticle-multihole states in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>31</mml:mn></mml:msup></mml:math>Mg and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>33</mml:mn></mml:msup></mml:math>Mg: A critical evaluation

Neyens, G.

doi:10.1103/physrevc.84.064310

Cited by 38 publications

(43 citation statements)

References 47 publications

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“…A narrow longitudinal momentum distribution (150 ± 3 MeV/c) of 32 Mg was observed in the knockout reaction of this (S n = 2.22 MeV) nucleus [11]. The measured longitudinal momentum distribution was in good agreement with both ground state spin of either 3/2 + or 3/2 − , considering mixed configurations of 32 Mg in excited states coupled with a neutron in the sd-pf shell [11,12]. In this article, we report the first direct experimental evidence for a multiparticle-hole ground state configuration of the neutron-rich 33 Mg isotope, and significant reduction as well as merging of the sd-pf shell gaps at N = 20 and 28, obtained via intermediate energy (400 A MeV) Coulomb dissociation measurements.…”

Section: Introductionsupporting

confidence: 63%

“…The observation of the breakdown of traditional magic numbers [1] in exotic nuclei far from the β-stability line has been an important issue in nuclear structure physics and significant effort has been put into both experimental investigations [2][3][4][5][6][7][8][9][10][11][12] and theoretical studies [13][14][15][16]. The first observation of the disappearance of the so-called magic number was reported by Thibault et al [2], based on mass measurements of the neutron-rich 31,32 Na isotopes [2].…”

Section: Introductionmentioning

confidence: 99%

“…Many different experiments [3,6,[8][9][10][11][12] have been performed to unravel the structure of 33 Mg (N = 21) but until now neither the ground state parity nor the shell configuration has been confirmed. From the measured negative sign of the magnetic moment, a pure 3p-2h ground state configuration and 3/2 − ground state spin and parity were suggested [10].…”

Section: Introductionmentioning

confidence: 99%

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Direct experimental evidence for a multiparticle-hole ground state configuration of deformedMg33

Pramanik¹,

Rahaman²,

Aumann³

et al. 2016

Phys. Rev. C

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Section: Introductionsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Direct experimental evidence for a multiparticle-hole ground state configuration of deformedMg33

Pramanik¹,

Rahaman²,

Aumann³

et al. 2016

Phys. Rev. C

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“…The primary * Electronic address: rraut@alpha.iuc.res.in motivation has been to probe the evolving structure of these nuclei belonging to the transitional region between the line of stability and the island of inversion [5,6]. A preferential occupation of the f p-shell configurations even at lower excitation energies and the development of collectivity based on pure sd configurations is indicated for these nuclei.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopy and shell model calculations in Si isotopes

Bhattacharjee

Raut

et al. 2015

Phys. Rev. C

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The 29 Si nucleus has been studied using heavy-ion induced fusion-evaporation reaction and, for the first time, using a large array of high resolution γ-ray detectors. High spin states of the nucleus have been populated using 18 O( 16 O,αn) and 18 O( 13 C,2n) reactions at E lab = 30-34 MeV. Previously reported levels have been confirmed and a new level has been identified in the present study. Spin-parity assignments have been carried out based on the anisotropy and polarization measurements of the observed γ-transitions. Level lifetimes have been measured using Doppler Shift Attenuation Method (DSAM), with modified analysis techniques for the thick molecular target (Ta2O5) used in the present setup. Lifetime of the lowest negative parity state at Ex = 3624 keV has been substantially modified from the previously reported value. Large basis shell model calculations have been carried out for the nucleus using updated interactions and the results corroborate the experimental findings. The calculations have also been carried out for the neighbouring 28,30 Si isotopes. In case of the 28 Si nucleus, the calculations adequately reproduce most of the deformed structures, as represented by the quadrupole moments extracted therefrom. In the 30 Si nucleus, the negative parity states have been reproduced for the first time without any ad hoc lowering of the single particle energies. It can be generally stated that the shell model calculations adequately describe the experimental observations in these nuclei.

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“…As a successful example, readers are directed to Ref. [31] in which the low-lying spectrum of 31 Mg is predicted; this spectrum has recently been confirmed by experiments [37].…”

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confidence: 99%

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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Multiparticle-multihole states in31Mg and33Mg: A critical evaluation

Cited by 38 publications

References 47 publications

Direct experimental evidence for a multiparticle-hole ground state configuration of deformedMg33

Direct experimental evidence for a multiparticle-hole ground state configuration of deformedMg33

Spectroscopy and shell model calculations in Si isotopes

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

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