Search for strongly deformed structures and observation of multiple nucleon alignments in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">W</mml:mi><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>174</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>

Knox, A.J.; Parnell-Lampen, C.; Tandel, U. S.; Chowdhury, P.; Carpenter, M. P.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Seweryniak, D.; Wang, X.; Zhu, S.; Hartley, D. J.; Zhang, Jingye

doi:10.1103/physrevc.77.024313

Cited by 14 publications

(13 citation statements)

References 32 publications

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“…The MOI of the s bands are indicated at twice the respective values for the g bands [ Fig. 2(b)] in accordance with observed trends for prolate g and s bands in this region [22][23][24]. The agreement between the expected MOI for the oblate s band and that of band 2 at the highest spins is striking.…”

supporting

confidence: 83%

“…2(b)]. This is considerably higher than any of the other collective or two-quasiparticle high-K bands in 180 Hf, but is less than that expected for the prolate s band (%60-65@ 2 MeV À1 , from a survey of nuclei in this region wherein states well above the g-and s-band crossing are known) [22][23][24]. The MOI of band 2 beyond I ¼ 14@ is, however, consistent with that expected for an oblate s band, assuming the same quadrupole deformation () for the prolate and oblate g bands (in accordance with predictions described below), and a proportionate increase in the MOI from the g-to s-band structure, similar to the prolate states.…”

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confidence: 93%

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Collective Oblate Rotation at High Spins in Neutron-RichHf180

et al. 2008

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We report on experimental evidence for collective oblate rotation becoming favored at high spins in a rigid, well-deformed, axially symmetric nucleus. Excited states established up to spin 20variant Planck's over 2pi in 180Hf are consistent with predictions that nucleon alignments would favor oblate over prolate shapes at high spins in neutron-rich Hf isotopes. The results highlight the influence of valence orbitals on the interplay between nucleon alignments and nuclear shapes and provide a rare example of independent particle dynamics in competing potential wells.

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confidence: 83%

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confidence: 93%

Collective Oblate Rotation at High Spins in Neutron-RichHf180

et al. 2008

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“…Five γ -γ coincidence spectra selecting the decay flow through the strongest low-K bands (labeled 1, 2, 3, 4, and 6 in Refs. [14,23]) were constructed by setting gates on clean transitions in the spin range ≈16-38h, in addition to a narrow gate on the prompt peak in the HELENA time spectrum. Each spectrum was corrected for the background under the energygate peaks by subtracting a properly normalized fraction of an ungated matrix.…”

Section: The Experimentsmentioning

confidence: 99%

“…The work aims at contributing to a global understanding of the K-hindrance phenomenon as a function of excitation energy by looking at the average properties of γ -decay fluxes in 174 W, populating quasicontinuum γ -γ coincidence spectra. This nucleus is characterized by the existence of a number of low-K bands (K 6) extending up to spin 39h and by three high-K rotational structures (K 8), two of which (K π = 8 − and 12 + ) were built on isomeric states with lifetimes longer than 120 ns [14,23]. In particular, the 12 + isomer represents a peculiarity in the mass region A ≈ 180, since its decay probability deviates strongly from the prediction by a γtunneling model, which accounts for the majority of isomeric decays in neighboring systems [12,14].…”

Section: Introductionmentioning

confidence: 99%

Global properties ofKhindrance probed by theγdecay of the warm rotating174W nucleus

Vandone¹,

Leoni²,

Blasi³

et al. 2013

Phys. Rev. C

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The K hindrance to the γ decay is studied in the warm rotating 174 W nucleus, focusing on the weakening of the selection rules of the K quantum number with increasing excitation energy. 174 W was populated by the fusion reaction of 50 Ti (at 217 MeV) on a 128 Te target, and its γ decay was detected by the AGATA Demonstrator array coupled to a BaF 2 multiplicity filter at Laboratori Nazionali di Legnaro of INFN. A fluctuation analysis of γ coincidence matrices gives a similar number of low-K and high-K discrete excited bands. The results are compared to simulations of the γ -decay flow based on a microscopic cranked shell model at finite temperature in which the K mixing is governed by the interplay of Coriolis force with the residual interaction. Agreement between simulations and experiment is obtained only by hindering the E1 decay between low-K and high-K bands by an amount compatible with that determined by spectroscopic studies of K isomers in the same mass region, with a similar trend with excitation energy. The work indicates that K mixing due to temperature effects may play a leading role for the entire body of discrete excited bands, which probes the onset region of K weakening.

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“…4, we can see that the experimental yrast band is quite well reproduced with PSM calculations. This nucleus is also characterized by low-K and high-K bands up to highly excited states, 39h [44]. In particular, two high-K bands based on K = 8 and K = 12 isomeric states with half-lives of 158 ns and 128 ns have been observed [42].…”

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Systematic study of multi-quasiparticleK-isomeric bands in tungsten isotopes by the extended projected shell model

Ghorui

Wang

et al. 2017

Phys. Rev. C

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Background:The interplay between collective and single-particle degrees of freedom is an important structure aspect to study. The nuclei in the A ≈ 180 mass region are often denoted as good examples to study such problems because these nuclei are known to exhibit many rotational bands based on multi-quasiparticle K isomers. Purpose: A large set of high-quality experimental data on high-K isomeric states in the A ≈ 180 mass region has accumulated. A systematic description of them is a theoretical challenge as it requires a method going beyond the usual mean field with multi-quasiparticle configurations built in the shell-model basis. The K-isomer data provide an ideal testing ground for theoretical models. Method:The recently extended projected shell model (PSM) by the Pfaffian method is employed with a sufficiently large configuration space including up to 10 quasiparticles. The restoration of rotational symmetry which is broken in the deformed mean field is obtained by means of angular-momentum projection. With axial symmetry in the basis deformation, each multi-quasiparticle state, classified by a K quantum number, represents the major component of a rotational K band. Shell-model diagonalization in such a projected basis defines the K mixing, which is the key ingredient of the present method. Results: Quasiparticle structure and rotational properties of high-K isomers in even-even neutron-rich 174−186 W isotopes are described. The rotational evolution of the yrast and near-yrast bands is discussed with successive band crossings. Multi-quasiparticle K isomers and associated rotational bands in each W isotope are studied with detailed quasiparticle configurations given. Electromagnetic transition properties are also studied and the calculated B(E2), B(M1), and g-factors are compared with experiment if data exist. Conclusions: Many nuclei of the A ≈ 180 mass region exhibit properties of an axially symmetric shape and K is approximately a good quantum number. For such nuclei, the extended PSM assuming an axially symmetric basis but including K mixing through diagonalization of the two-body Hamiltonian is an appropriate method to study multi-quasiparticle K isomers and K violations in these states. For special examples where one finds highly K-forbidden transitions the present model needs to be further improved.

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Search for strongly deformed structures and observation of multiple nucleon alignments inW174

Cited by 14 publications

References 32 publications

Collective Oblate Rotation at High Spins in Neutron-RichHf180

Collective Oblate Rotation at High Spins in Neutron-RichHf180

Global properties ofKhindrance probed by theγdecay of the warm rotating174W nucleus

Systematic study of multi-quasiparticleK-isomeric bands in tungsten isotopes by the extended projected shell model

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