Study of neutron-deficient mercury isotopes Preliminary results on <sup>189</sup>Hg

Zanon, I.; Siciliano, M.; Goasduff, A.; John, Philipp R.

doi:10.1051/epjconf/201922301072

Cited by 2 publications

(2 citation statements)

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“…The neutrons evaporated in the reaction were detected using the Neutron Wall array [36], composed of 45 liquid scintillators placed at forward angles with respect to the beam direction. The use of Neutron Wall was necessary to discriminate between the events of interest, expected in coincidence with at least one neutron, and the Coulomb-excitation background [37]. Figure 2 (top panel) shows the γ-ray energy spectrum of 188 Hg, obtained in coincidence with at least one neutron and gated on the 2 + 1 → 0 + g.s.…”

Section: Methodsmentioning

confidence: 99%

Shape coexistence in the neutron-deficient $^{188}$Hg investigated via lifetime measurements

Siciliano,

Zanon,

Goasduff

et al. 2020

Preprint

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Background: Shape coexistence in the Z ≈ 82 region has been established in mercury, lead and polonium isotopes. For even-even mercury isotopes with 100 ≤ N ≤ 106 multiple fingerprints of this phenomenon are observed, which seems to be no longer present for N ≥ 110. According to a number of theoretical calculations, shape coexistence is predicted in the 188 Hg isotope. Purpose: The aim of this work was to measure lifetimes of excited states in 188 Hg to infer their collective properties, such as the deformation. Extending the investigation to higher-spin states, which are expected to be less affected by band-mixing effects, can provide additional information on the coexisting structures. Methods: The 188 Hg nucleus was populated using two different fusion-evaporation reactions with two targets, 158 Gd and 160 Gd, and a beam of 34 S provided by the Tandem-ALPI accelerator complex at the Laboratori Nazionali di Legnaro. The channels of interest were selected using the information from the Neutron Wall array, while the γ rays were detected using the GALILEO γ-ray spectrometer. Lifetimes of excited states were determined using the Recoil Distance Doppler-Shift method, employing the dedicated GALILEO plunger device. Results: Lifetimes of the states up to spin 16 were measured and the corresponding reduced transition probabilities were calculated. Assuming two-band mixing and adopting, as done commonly, the rotational model, the mixing strengths and the deformation parameters of the unperturbed structures were obtained from the experimental results. In order to shed light on the nature of the observed configurations in the 188 Hg nucleus, the extracted transition strengths were compared with those resulting from state-of-the-art beyond-mean-field calculations using the symmetry-conserving configuration-mixing approach, limited to axial shapes, and the 5-dimensional collective Hamiltonian, including the triaxial degree of freedom. Conclusions: The first lifetime measurement for states with spin ≥ 6 suggested the presence of an almost spherical structure above the 12 + 1 isomer and allowed elucidating the structure of the intruder band. The comparison of the extracted B(E2) strengths with the two-band mixing model allowed the determination of the ground-state band deformation. Both beyond-mean-field calculations predict coexistence of a weakly-deformed band with a strongly prolate-deformed one, characterized by elongation parameters similar to those obtained experimentally, but the calculated relative position of the bands and their mixing strongly differ.

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Section: Methodsmentioning

confidence: 99%

Shape coexistence in the neutron-deficient $^{188}$Hg investigated via lifetime measurements

Siciliano,

Zanon,

Goasduff

et al. 2020

Preprint

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“…One of the prevailing interests in nuclear physics is to unravel the nuclear structure to explore the collective properties in the neighbourhood of magic numbers as well as the atomic transitions of rare-earth nuclei [1][2][3][4]. The nuclear isotopic shift emerges as one of the viable tools which serve as a premise for testing nuclear theories [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Isotopic Shift in Hg-Isotopes within Brückner versus Relativistic Energy Density Functional

et al. 2022

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The present study is focused on revealing a characteristic kink of the neutron shell closure N = 126 across the Hg-isotopic chain within the relativistic mean-field (RMF) approach with the IOPB-I, DD-ME2, DD-PC1 and NL3 parameter sets. The RMF densities are converted to their spherical equivalence via the Wood–Saxon approximation and used as input within the parametrization procedure of the coherent density fluctuation model (CDFM). The nuclear matter symmetry energy is calculated using the Brückner energy density functional, and its surface, as well as volume components, are evaluated within Danielwicz’s liquid drop prescription. In addition, a comparison between Brückner and relativistic energy density functionals using the NL3 parameter set is shown as a representative case. The binding energy, charge distribution radius and symmetry energy are used as indicators of the isotopic shift in both ground and isomeric states. We have found the presence of a kink at the shell/sub-shell closure at N = 126 for neutron-rich 206Hg. The formation of the kink is traceable to the early filling of the 1i11/2 orbitals rather than 2g9/2, due to the large spin-orbit splitting. As such, the link between the occupational probability and the magicity of nuclei over the Hg-isotopic chain is established.

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Study of neutron-deficient mercury isotopes Preliminary results on ¹⁸⁹Hg

Cited by 2 publications

References 18 publications

Shape coexistence in the neutron-deficient $^{188}$Hg investigated via lifetime measurements

Shape coexistence in the neutron-deficient $^{188}$Hg investigated via lifetime measurements

Isotopic Shift in Hg-Isotopes within Brückner versus Relativistic Energy Density Functional

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Study of neutron-deficient mercury isotopes Preliminary results on 189Hg

Cited by 2 publications

References 18 publications

Shape coexistence in the neutron-deficient $^{188}$Hg investigated via lifetime measurements

Shape coexistence in the neutron-deficient $^{188}$Hg investigated via lifetime measurements

Isotopic Shift in Hg-Isotopes within Brückner versus Relativistic Energy Density Functional

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Study of neutron-deficient mercury isotopes Preliminary results on ¹⁸⁹Hg