Study of 0[sup +] excitations in [sup 158]Gd with the (n,n[sup ʹ]γ) reaction

Lesher, S. R.; Ammar, Z.; Merrick, M.; Hannant, C. D.; Warr, N.; Brown, T. B.; Boukharouba, N.; Fransen, C.; McEllistrem, M. T.; Yates, S. W.

doi:10.1063/1.1470038

Cited by 4 publications

(7 citation statements)

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“…The number of 0 + states in an even-even nucleus can be large. The first example found experimentally in 2002 was 158 Gd, in which 13 excited 0 + states have been found below 3.1 MeV [492][493][494][495]. Many theoretical interpretations have been suggested for these 0 + states, including two-phonon octupole character [496], the pseudo-SU(3) model [497][498][499], the quasiparticle-phonon model [500], and the pairing plus quadrupole model [501].…”

Section: The Nature Of 0 + Statesmentioning

confidence: 99%

Shape Coexistence in Even–Even Nuclei: A Theoretical Overview

Bonatsos,

Martinou,

Peroulis

et al. 2023

Atoms

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The last decade has seen a rapid growth in our understanding of the microscopic origins of shape coexistence, assisted by the new data provided by the modern radioactive ion beam facilities built worldwide. Islands of the nuclear chart in which shape coexistence can occur have been identified, and the different microscopic particle–hole excitation mechanisms leading to neutron-induced or proton-induced shape coexistence have been clarified. The relation of shape coexistence to the islands of inversion, appearing in light nuclei, to the new spin-aligned phase appearing in N=Z nuclei, as well as to shape/phase transitions occurring in medium mass and heavy nuclei, has been understood. In the present review, these developments are considered within the shell-model and mean-field approaches, as well as by symmetry methods. In addition, based on systematics of data, as well as on symmetry considerations, quantitative rules are developed, predicting regions in which shape coexistence can appear, as a possible guide for further experimental efforts that can help in improving our understanding of the details of the nucleon–nucleon interaction, as well as of its modifications occurring far from stability.

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Section: The Nature Of 0 + Statesmentioning

confidence: 99%

Shape Coexistence in Even–Even Nuclei: A Theoretical Overview

Bonatsos,

Martinou,

Peroulis

et al. 2023

Atoms

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“…The PSM calculations of the transition from the i-th 0 + state to the 2 + g state, B(E2, 0 + i → 2 + g ), are listed in Table I. Comparing the theoretical B(E2) values with the experimental data [18], we found that the numbers (in W.u.) listed in Table I are one or two orders of magnitude too small for many of the transitions.…”

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confidence: 89%

“…al. [18] are in average of two orders of magnitude smaller than the in-band B(E2) values of the ground-state band (typically, a few hundred W.u.). These small B(E2) values usually indicate that the observed 0 + states in Ref.…”

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Nature of excited0+states inGd158described by the projected shell model

et al. 2003

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Excited 0 + states are studied in the framework of the projected shell model, aiming at understanding the nature of these states in deformed nuclei in general, and the recently observed 13 excited 0 + states in 158 Gd in particular. The model, which contains projected two-and four-quasiparticle states as building blocks in the basis, is able to reproduce reasonably well the energies for all the observed 0 + states. The obtained B(E2) values however tend to suggest that these 0 + states might have a mixed nature of quasiparticle excitations coupled to collective vibrations.PACS numbers: 21.60. Cs, 23.20.Lv, 27.70.+q Dynamic perturbations of nuclear shapes around the equilibrium can give rise to physical states at low to moderate excitation energies. Classical examples of such motion are β and γ vibrations [1,2], in which nucleons undergo vibrations in a collective manner. Traditionally, the first excited K π = 0 + states and the first excited 2 + states are interpreted, respectively, as the β and γ vibrational states. While the 2 + collective excitations are better understood theoretically, the nature of the lowest 0 + excitation of deformed nuclei still remains under debate [3,4,5,6,7]. The physics of higher 0 + states is even more complex because, on one side, they can predominantly be multi-phonon states based on the single-phonons [8], and on the other side, they can be quasiparticle (qp) excitations in nature. The real situation is, perhaps, that the two aspects, collective excitations and qp states, are mixed by residual interactions.Data on K π = 0 + states have been relatively sparse. In a very recent work by Lesher et. al.[9], a remarkable (p, t) experiment revealed a total of 13 excited 0 + states in 158 Gd, below an excitation energy of approximately 3.1 MeV. This abundance of 0 + states in a single nucleus provides significant new information on the poorly understood phenomenon, which has immediately sparked off theoretical interest. For this energy range, one may think about an explanation through collective modes. In fact, Zamfir, Zhang, and Casten [10] suggested that many of the observed 0 + states may be of two-phonon octupole character. Nevertheless, these authors warned also that, although the mechanism was excluded in their collective models, many of the 0 + states in this excitation energy range may be predominantly two-qp in character.The purpose of the present paper is to investigate whether one can explain the nature of the observed 0 + states in terms of qp excitations. In contrast to Ref.[10], our calculation here does not emphasize the aspect of collective excitation. Although, similar to the work of Zamfir, Zhang, and Casten [10], we may provide only a partial image, our results may shed light on the importance of considering the qp aspects in understanding the nature of these 0 + states.Our study is based on the projected shell model (PSM)[11]. The PSM is the spherical shell model built on a deformed basis. The PSM calculation usually begins with the deformed Nilsson single-particle...

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“…Lesher et al [11] studied the 158 Gd (n, n′γ)-reaction with neutron energy up to 3.3 MeV to observe collective states of 0 + and found two phonon γγ-strengths at 2276.7 keV. In another experiment, 13 excited 0 + states below 3.1 MeV were observed in the 158 Gd nucleus by (p, t)-reactions [12]. Levon et al [13] found collective properties of 0 + levels in 158 Gd nuclei up to 4.2 MeV.…”

Section: Introductionmentioning

confidence: 99%

Description of energy levels and decay properties in 158Gd nucleus

Radhi,

Kassim,

Al-Jubbori

et al. 2023

Nucl. Phys. At. Energy

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In this paper, IBM-1 and IBM-2 with a SU(3) limit are used to describe the 158Gd isotope. The calculations of energy levels in the ground state, beta-, and gamma-bands are made up, which account for 15 energy levels. However, we found that the energy states of the same spin of the beta- and vibrational bands become degenerate states. In breaking the SU(3) dynamical symmetry by introducing a value of pairing interaction, the degeneracy is lifted and the energy levels are brought up to the same order as the experimental ones.

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Study of 0[sup +] excitations in [sup 158]Gd with the (n,n[sup ʹ]γ) reaction

Cited by 4 publications

References 1 publication

Shape Coexistence in Even–Even Nuclei: A Theoretical Overview

Shape Coexistence in Even–Even Nuclei: A Theoretical Overview

Nature of excited0+states inGd158described by the projected shell model

Description of energy levels and decay properties in 158Gd nucleus

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