Interplay of quasiparticle and vibrational excitations: First observation of isomeric states in 168Dy and 169Dy

Zhang, G.X.; Watanabe, H.; Dracoulis, George; Kondev, F. G.; Lane, G. J.; Regan, P. H.; Söderström, P.-A.; Walker, P. M.; Yoshida, Kenichi; Kanaoka, H.; Korkulu, Z.; Lee, P.S.; Liu, J.J.; Nishimura, S.; Wu, J.; Yagi, A.; Ahn, D. S.; Alharbi, T.; Baba, H.; Browne, F.; Bruce, A. M.; Carpenter, M. P.; Carroll, R.; Chae, K. Y.; Chiara, C. J.; Dombrádi, Zs.; Doornenbal, P.; Estradé, A.; Fukuda, N.; Griffin, C. J.; Ideguchi, E.; Inabe, N.; Isobe, T.; Kanaya, S.; Kojouharov, I.; Kubo, T.; Kubo, T.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lauritsen, T.; Lee, C.S.; Lee, E.J.; Lister, C. J.; Lorusso, G.; Lotay, G.; McCutchan, E.A.; Moon, C.-B.; Nishizuka, I.; Niță, Cristina; Odahara, A.; Patel, Z.; Phong, V. H.; Podolyák, Zs.; Roberts, O. J.; Sakuraï, H.; Schaffner, H.; Seweryniak, D.; Shand, C.; Shimizu, Y.; Sumikama, T.; Suzuki, Hiroshi; Takeda, Hiroyuki; Terashima, S.; Vajta, Zs.; Valiente-Dobón, J.J.; Xu, Z. Y.; Zhu, S.

doi:10.1016/j.physletb.2019.135036

Cited by 12 publications

(11 citation statements)

References 36 publications

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“…Note that the pnQRPA calculations including the dynamic spin-triplet pairing with more or less the same strength as the spin-singlet pairing describe well the characteristic low-lying Gamow- Teller strength distributions in the light N Z nuclei [38][39][40], and the β-decay half-lives of neutron-rich Ni isotopes [41]. Furthermore, the present theoretical framework describes well the measured giant resonances in light, medium-heavy, and heavy nuclei [21,36,[42][43][44][45][46][47][48], and low-lying collective modes of vibration [21,[49][50][51][52][53].…”

Section: B Numerical Proceduressupporting

confidence: 64%

Isovector giant monopole and quadrupole resonances in a Skyrme energy density functional approach with axial symmetry

Yoshida

2021

Phys. Rev. C

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Background: Giant resonance (GR) is a typical collective mode of vibration. The deformation splitting of the isovector (IV) giant dipole resonance is well established. However, the splitting of GRs with other multipolarities is not well understood. Purpose: I explore the IV monopole and quadrupole excitations and attempt to obtain the generic features of IV giant resonances in deformed nuclei by investigating the neutral and charge-exchange channels simultaneously. Method: I employ a nuclear energy-density functional (EDF) method: the Skyrme-Kohn-Sham-Bogoliubov and the quasiparticle random-phase approximation are used to describe the ground state and the transition to excited states. Results: I find the concentration of the monopole strengths in the energy region of the isobaric analog or Gamow-Teller resonance irrespective of nuclear deformation, and the appearance of a high-energy giant resonance composed of the particle-hole configurations of 2 hω 0 excitation. Splitting of the distribution of the strength occurs in the giant monopole and quadrupole resonances due to deformation. The lower K states of quadrupole resonances appear lower in energy and possess the enhanced strengths in the prolate configuration, and vice versa in the oblate configuration, while the energy ordering depending on K is not clear for the J = 1 and J = 2 spin-quadrupole resonances. Conclusions: The deformation splitting occurs generally in the giant monopole and quadrupole resonances. The K dependence of the quadrupole transition strengths is largely understood by the anisotropy of density distribution.

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Section: B Numerical Proceduressupporting

confidence: 64%

Isovector giant monopole and quadrupole resonances in a Skyrme energy density functional approach with axial symmetry

Yoshida

2021

Phys. Rev. C

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“…Version available at http://www.nndc.bnl.gov/ensarchivals/ accessed on 17 September 2020) [6]. Measurements of isomers and their properties continue to be a point of experimental interest for a variety of reasons, including not only as astrophysical model inputs, but also for applications in industry, medicine, and tests of fundamental nuclear physics [7][8][9][10][11][12][13][14][15][16][17]. For a recent review, see [18].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Neutron-Rich Nuclear Isomer Behavior to Uncertainties in Direct Transitions

et al. 2021

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Nuclear isomers are populated in the rapid neutron capture process (r process) of nucleosynthesis. The r process may cover a wide range `of temperatures, potentially starting from several tens of GK (several MeV) and then cooling as material is ejected from the event. As the r-process environment cools, isomers can freeze out of thermal equilibrium or be directly populated as astrophysically metastable isomers (astromers). Astromers can undergo reactions and decays at rates very different from the ground state, so they may need to be treated independently in nucleosythesis simulations. Two key behaviors of astromers—ground state ↔ isomer transition rates and thermalization temperatures—are determined by direct transition rates between pairs of nuclear states. We perform a sensitivity study to constrain the effects of unknown transitions on astromer behavior. Detailed balance ensures that ground → isomer and isomer → ground transitions are symmetric, so unknown transitions are equally impactful in both directions. We also introduce a categorization of astromers that describes their potential effects in hot environments. We provide a table of neutron-rich isomers that includes the astromer type, thermalization temperature, and key unmeasured transition rates.

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“…3(b) the intrinsic excitation energies of the quadrupole (λ = 2) K π = 2 + state in the N = 150 isotones. The excitation energy calculated is higher than that of a typical γ vibration: experimentally, the 2 + 2 states were observed at low excitation energies (≈ 800 keV) for the well-deformed dysprosium (Z = 66) and erbium (Z = 68) isotopes around N = 98 [46] and in the neutron-rich region [55,56]. It is noted that the present nuclear EDF method well describes the γ vibration in the neutron-rich Dy isotopes [57] as well as in the Mg isotopes [30,58].…”

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confidence: 99%

Pairing and nonaxial-shape correlations in N=150 isotones

Yoshida

2021

Phys. Rev. C

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Background: Rotational bands have been measured around 250 Fm associated with strong deformed-shell closures. The K π = 2 − excited band emerges systematically in N = 150 isotones raging from plutonium to nobelium with even-Z numbers, and a sharp drop in energies was observed in californium.Purpose: I attempt to uncover the microscopic mechanism for the appearance of such a low-energy 2 − state in 248 Cf. Furthermore, I investigate the possible occurrence of the low-energy K π = 2 + state, the γ vibration, to elucidate the mechanism that prefers the simultaneous breaking of the reflection and axial symmetry to the breaking of the axial symmetry alone in this mass region.Method: I employ a nuclear energy-density functional (EDF) method: the Skyrme-Kohn-Sham-Bogoliubov and the quasiparticle random-phase approximation are used to describe the ground state and the transition to excited states. Results:The Skyrme-type SkM* and SLy4 functionals reproduce the fall in energy but not the absolute value of the K π = 2 − state at Z = 98 where the proton two-quasiparticle excitation [633]7/2 ⊗ [521]3/2 plays a decisive role for the peculiar isotonic dependence. I find interweaving roles by the pairing correlation of protons and the deformed-shell closure at Z = 98. The SkM* model predicts the K π = 2 − state appears lower in energy in 246 Cf than in 248 Cf as the Fermi level of neutrons is located in between the [622]5/2 and the [734]9/2 orbitals. Except for 250 Fm in the SkM* calculation, the K π = 2 + state is predicted to appear higher in energy than the K π = 2 − state because the quasiproton [521]1/2 orbital is located above the [633]7/2 orbital. Conclusions:A systematic study of low-lying collective states in heavy actinide nuclei provides a rigorous testing ground for microscopic nuclear models. The present paper shows a need for improvements in the EDFs to describe pairing correlations and shell structures in heavy nuclei, that are indispensable in predicting the heaviest nuclei.

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Interplay of quasiparticle and vibrational excitations: First observation of isomeric states in 168Dy and 169Dy

Cited by 12 publications

References 36 publications

Isovector giant monopole and quadrupole resonances in a Skyrme energy density functional approach with axial symmetry

Isovector giant monopole and quadrupole resonances in a Skyrme energy density functional approach with axial symmetry

Sensitivity of Neutron-Rich Nuclear Isomer Behavior to Uncertainties in Direct Transitions

Pairing and nonaxial-shape correlations in N=150 isotones

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