| 1. |
- Bree, N, et al.
(författare)
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Shape Coexistence in the Neutron-Deficient Even-Even Hg182-188 Isotopes Studied via Coulomb Excitation.
- 2014
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Ingår i: Physical Review Letters. - 1079-7114. ; 112:16
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Tidskriftsartikel (refereegranskat)abstract
- Coulomb-excitation experiments to study electromagnetic properties of radioactive even-even Hg isotopes were performed with 2.85 MeV/nucleon mercury beams from REX-ISOLDE. Magnitudes and relative signs of the reduced E2 matrix elements that couple the ground state and low-lying excited states in Hg182-188 were extracted. Information on the deformation of the ground and the first excited 0+ states was deduced using the quadrupole sum rules approach. Results show that the ground state is slightly deformed and of oblate nature, while a larger deformation for the excited 0+ state was noted in Hg182,184. The results are compared to beyond mean field and interacting-boson based models and interpreted within a two-state mixing model. Partial agreement with the model calculations was obtained. The presence of two different structures in the light even-mass mercury isotopes that coexist at low excitation energy is firmly established.
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| 2. |
- Lewis, M. C., et al.
(författare)
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Decay of a 19(-) isomeric state in Lu-156
- 2018
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 98:2
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Tidskriftsartikel (refereegranskat)abstract
- A multiparticle spin-trap isomeric state having a half-life of 179(4) ns and lying 2601 keV above the yrast 10(+) state in Lu-156 has been discovered. The Lu-156 nuclei were produced by bombarding isotopically enriched Cd-106 targets with beams of Ni-58 ions, separated in flight using the gas-filled separator RITU and their decays were measured using the GREAT spectrometer. Analysis of the main decay path that populates yrast states observed previously suggests a spin-parity assignment of 19(-) for the isomeric state, which is consistent with isomeric states identified in the N = 85 isotones. Comparison with other decay paths in Lu-156 indicates that the [pi h(11/)(2)(-1) circle times nu h(9/2)]10(+) state at the bottom of the yrast sequence is likely to be the a-decaying isomeric state, with the [pi h(11/)(2)(-1) circle times nu f(7/2)]9(+) state lying 62 keV above it. The relative ordering of the lowest-lying 9(+) and 10(+) states is inverted in Lu-156 compared with its odd-odd isotones.
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| 3. |
- Lv, B. F., et al.
(författare)
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Chirality of Nd-135 reexamined : Evidence for multiple chiral doublet bands
- 2019
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 100:2
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Tidskriftsartikel (refereegranskat)abstract
- One new pair of positive-parity chiral doublet bands have been identified in the odd-A nucleus Nd-135 which together with the previously reported negative-parity chiral doublet bands constitute a third case of multiple chiral doublet (M chi D) bands in the A approximate to 130 mass region. The properties of the M chi D bands are well reproduced by constrained covariant density functional theory and particle rotor model calculations. The newly observed M chi D bands in Nd-135 represents an important milestone in supporting the existence of M chi D in nuclei.
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| 4. |
- Lv, B. F., et al.
(författare)
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Evidence against the wobbling nature of low-spin bands in 135Pr
- 2022
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 824
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Tidskriftsartikel (refereegranskat)abstract
- The electromagnetic character of the ΔI=1 transitions connecting the 1- to 0-phonon and the 2- to 1-phonon wobbling bands should be dominated by an E2 component, due to the collective motion of the entire nuclear charge. In the present work it is shown, based on combined angular correlation and linear polarization measurements, that the mixing ratios of all analyzed connecting transitions between low-lying bands in 135Pr interpreted as 0-, 1-, and 2-phonon wobbling bands, have absolute values smaller than one. This indicates predominant M1 magnetic character, which is incompatible with the proposed wobbling nature. All experimental observables are instead in good agreement with quasiparticle-plus-triaxial-rotor model calculations, which describe the bands as resulting from a rapid re-alignment of the total angular momentum from the short to the intermediate nuclear axis.
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| 5. |
- Lv, B. F., et al.
(författare)
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Tilted precession bands in Nd 135
- 2021
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 103:4
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Tidskriftsartikel (refereegranskat)abstract
- Two new excited bands built on the πh11/2 configuration have been identified in Nd135 in addition to the known πh11/2 band. The energy spectra of the excited bands and the available electromagnetic transition probabilities are in good agreement with theoretical results obtained using quasiparticle-plus-triaxial-rotor model calculations. The properties of the bands identify them as tilted precession bands instead of wobbling bands. Our results give a new insight into the interpretation of the low-lying bands in odd-A mass nuclei, and can stimulate future studies to address the nuclear triaxiality.
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| 6. |
- Parr, E., et al.
(författare)
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Fine structure in the alpha decay of high-spin isomers in Lu-155 and Hf-156
- 2018
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 98:2
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Tidskriftsartikel (refereegranskat)abstract
- Fine structure in the a decay of high-spin isomers in Lu-155( 25/2(-)) and Hf-156(8(+))has been studied for the first time using alpha gamma- coincidence analysis. Three new a decays from Lu-155(25/2(-)) and two from Hf-156(8(+)) have been identified, populating seniority s > 1 states in the N = 82 nuclei Tm-151 and Yb-152, respectively. The reduced hindrance factors of the a decays support the previous configuration assignments of the populated states. This is the first observation of states with excitation energy greater than 1.5 MeV being populated following a decay in nuclei outside of the Pb-208 region.
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| 7. |
- Petrache, C. M., et al.
(författare)
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Multiple chiral bands in 137 Nd
- 2020
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 56:8
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Tidskriftsartikel (refereegranskat)abstract
- Two new bands have been identified in 137Nd from a high-statistics JUROGAM II gamma-ray spectroscopy experiment. Constrained density functional theory and particle rotor model calculations are used to assign configurations and investigate the band properties, which are well described and understood. It is demonstrated that these two new bands can be interpreted as chiral partners of previously known three-quasiparticle positive- and negative-parity bands. The newly observed chiral doublet bands in 137Nd represent an important support to the existence of multiple chiral bands in nuclei. The present results constitute the missing stone in the series of Nd nuclei showing multiple chiral bands, which becomes the most extended sequence of odd–even and even-even nuclei presenting multiple chiral bands in the Segré chart.
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| 8. |
- Wrzosek-Lipska, K., et al.
(författare)
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Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes : Coulomb excitation of 182Hg, 184Hg, 186Hg and 188Hg
- 2019
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 55:8
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Tidskriftsartikel (refereegranskat)abstract
- The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass 182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of 01,2+, 21,2+ and 41+ states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.
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| 9. |
- Lv, B. F., et al.
(författare)
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Evolution from γ -soft to stable triaxiality in Nd 136 as a prerequisite of chirality
- 2018
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 98:4
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Tidskriftsartikel (refereegranskat)abstract
- The level structure of Nd136 has been investigated using the Mo100(Ar40,4n) reaction and the JUROGAM II+RITU+GREAT setup. The level scheme has been extended significantly. Many new bands have been identified both at low and high spin, among which are five nearly degenerate bands interpreted as chiral partners. Excitation energies, spins, and parities of the previously known bands are revised and firmly established, and some previously known bands have been revised. Configurations are assigned to the observed bands based on cranked Nilsson-Strutinsky calculations. The band structure of Nd136 is now clarified and the various types of single-particle and collective excitations are well understood.
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| 10. |
- Petrache, C. M., et al.
(författare)
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Highly deformed bands in Nd nuclei : New results and consistent interpretation within the cranked Nilsson-Strutinsky formalism
- 2019
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Ingår i: Physical Review C. - : American Physical Society (APS). - 2469-9985 .- 2469-9993. ; 100:5
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Tidskriftsartikel (refereegranskat)abstract
- Three new highly-deformed (HD) bands are identified in Nd136 and the highly deformed band of Nd137 is extended at higher spin by four transitions, revealing a band crossing associated with the occupation of the second νi13/2 intruder orbital. Extended cranked Nilsson-Strutinsky calculations are performed for all HD bands observed in Nd134, Nd136, and Nd137, achieving for the first time a consistent interpretation of all HD bands in the Nd nuclei. The new interpretation has significant consequences, like the change of parity of the yrast HD bands of Nd134 and Nd136, and the involvement of two negative-parity neutron intruder orbitals in the configurations of most HD bands. The present experimental results and their theoretical interpretation represent an important step forward in the understanding of the second-minimum excitations in the Nd nuclei.
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