Collectivity in 44S

Glasmacher, T.; Brown, B. A.; Chromik, M. J.; Cottle, P. D.; Fauerbach, M.; Ibbotson, R. W.; Kemper, K. W.; Morrissey, D. J.; Scheit, H.; Sklenicka, D.W.; Steiner, M.

doi:10.1016/s0370-2693(97)00077-4

Cited by 247 publications

(202 citation statements)

References 21 publications

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“…The efficiencies of the ␤ and ␥ detectors were measured using 45,46 Ar, [23][24][25][26] Ne, 90 Kr sources collected on line, corresponding to a broad energy range of emitted ␥ rays. The detection efficiency for ␤ particles was measured by comparing singles and ␤-gated Ge spectra and was found to be 35(4)%.…”

Section: A Experimentsmentioning

confidence: 99%

βdecay ofAr47

Weissman

Cederkäll

2004

Phys. Rev. C

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Information on ␤-decay properties of neutron-rich 47 Ar was obtained at the ISOLDE facility at CERN using isobaric selectivity. This was achieved by a combination of a plasma-ion source with a cooled transfer line and subsequent mass separation. A doubly charged beam was used in order to improve the signal-to-background ratio associated with multi-charged noble gas fission products. The identification of the 47 Ar ␥-ray transitions was performed by comparing the spectra obtained from direct proton bombardment of the target and of the neutron converter. New excited levels in the daughter 47 K nucleus corresponding to the negative-parity states were observed. The obtained data are compared to the result of large-scale shell model calculations and quasiparticle random-phase approximation predictions.

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Section: A Experimentsmentioning

confidence: 99%

βdecay ofAr47

Weissman

Cederkäll

2004

Phys. Rev. C

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“…Evidence for a breakdown of the traditional N = 28 magic number resulted from the pioneering observation of low-lying quadrupole collectivity in 44 S [1,2] and fueled the field of rare-isotope science in the quest to unravel the origin of shell and shape evolution in exotic nuclei with experimental programs worldwide.…”

Section: Introductionmentioning

confidence: 99%

In-beam γ -ray spectroscopy of S38–42

et al. 2016

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The low-energy excitation level schemes of the neutron-rich 38−42 S isotopes are investigated via in-beam γ-ray spectroscopy following the fragmentation of 48 Ca and 46 Ar projectiles on a 12 C target at intermediate beam energies. Information on γγ coincidences complemented by comparisons to shell-model calculations were used to construct level schemes for these neutron-rich nuclei. The experimental data are discussed in the context of large-scale shell-model calculations with the SDPF-MU effective interaction in the sd-pf shell. For the even-mass S isotopes, the evolution of the yrast sequence is explored as well as a peculiar change in decay pattern of the second 2 + states at N = 26. For the odd-mass 41 S, a level scheme is presented that seems complete below 2.2 MeV and consistent with the predictions by the SDPF-MU shell-model Hamiltonian; this is a remarkable benchmark given the rapid shell and shape evolution at play in the S isotopes as the broken-down N = 28 magic number is approached. Furthermore, the population of excited final states in projectile fragmentation is discussed.

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“…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.…”

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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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Collectivity in 44S

Cited by 247 publications

References 21 publications

βdecay ofAr47

βdecay ofAr47

In-beam γ -ray spectroscopy of S38–42

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

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