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| 2. |
- Riley, M. A., et al.
(author)
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Observation of states beyond band termination in Er-156,Er-157,Er-158 and strongly deformed structures in Hf-173,Hf-174,Hf-175
- 2006
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In: Physica Scripta. - 0031-8949. ; T125, s. 123-126
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Journal article (peer-reviewed)abstract
- High-spin terminating bands in heavy nuclei were first identified in nuclei around Er-158(90). While examples of terminating states have been identified in a number of erbium isotopes, almost nothing is known about the states lying beyond band termination. In the present work, the high-spin structure of Er-156,Er-157,Er-158 has been studied using the Gammasphere spectrometer. The subject of triaxial superdeformation and 'wobbling' modes in Lu nuclei has rightly attracted a great deal of attention. Very recently four strongly or superdeformed (SD) sequences have been observed in Hf-174, and cranking calculations using the Ultimate Cranker code predict that such structures may have significant triaxial deformation. We have performed two experiments in an attempt to verify the possible triaxial nature of these bands. A lifetime measurement was performed to confirm the large (and similar) deformation of the bands. In addition, a high-statistics, thin-target experiment took place to search for linking transitions between the SD bands, possible wobbling modes, and new SD band structures.
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| 3. |
- Riley, M A, et al.
(author)
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Beyond band termination in Er-157 and the search for wobbling excitations in strongly deformed Hf-174
- 2005
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In: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. 1735-1740
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Journal article (peer-reviewed)abstract
- High-spin terminating bands in heavy nuclei were first identified in nuclei around Er-158(90). While examples of special terminating states have been identified in a number of erbium isotopes, almost nothing is known about the states lying beyond band termination. In the present work the high-spin structure of Er-157 has been studied using the Gammasphere spectrometer. The subject of triaxial superdeformation and 'wobbling' modes in Lu nuclei has rightly attracted a great deal of attention. Very recently, four strongly or superdeformed (SD) sequences have been observed in Hf-174 and ultimate cranker calculations predict, such structures may have significant triaxial deformation. We have performed two experiments in an attempt to verify the possible triaxial nature of these bands. A lifetime measurement was performed to confirm the large (and similar) deformation of the bands. In addition, a high-statistics, thin-target experiment was run to search for linking transitions between the SD bands and possible wobbling modes.
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| 4. |
- Yadav, R. B., et al.
(author)
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Identification of triaxial strongly deformed bands in Hf-168
- 2008
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 78:4
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Journal article (peer-reviewed)abstract
- Possible decay pathways associated with three candidates for triaxial strongly deformed (TSD) bands in Hf-168 have been investigated. The spin and excitation energy of the strongest band, TSD1, were determined approximately based on gamma-ray coincidence relationships. Discrete links were established for the second band. The overall agreement between the observed properties of the bands and cranking calculations using the ULTIMATE CRANKER code provides strong support for an interpretation where band TSD1 is associated with a TSD minimum, (epsilon(2),gamma)similar to(0.43,20(degrees)), involving the pi(i(13/2))(2) and the nu(j(15/2)) high-j orbitals. This constitutes the first identification of a TSD band in Hf isotopes, which has been long-predicted by theoretical studies. The second band is understood as being associated with a near-prolate shape and a deformation enhanced with respect to the normal deformed bands. It is proposed to be built on the pi(i(13/2)h(9/2))circle times nu(i(13/2))(2) configuration.
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| 5. |
- Døssing, T, et al.
(author)
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Decay-Out Of Superdeformed Bands By Coupling To Ordered Or Chaotic Spectra
- 2005
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In: AIP Conference Proceedings. - : AIP. - 0094-243X. ; 764:1, s. 27-33
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Journal article (peer-reviewed)abstract
- Different treatments of the decay-out of superdeformed bands are reviewed, focusing on the role of the normally deformed doorway states to which the superdeformed band primarily couples at decay-out. A schematic description based on sparse GOE matrices is formulated for the normally deformed states including one doorway state. This allows for a gradual change of the normally deformed spectrum from an ordered to a chaotic situation by means of the effective dimensionality parameter. It is found that the distribution of the small normally deformed admixtures into the superdeformed band, through which it decays, depends sensitively on the effective dimensionality parameter. Analyzing the measured distribution of transition strength of decay-out gamma-ray lines in 194Hg, it is concluded that the spectrum of normally deformed states is closer to the chaotic than the ordered situation at the energy and angular momentum of the superdeformed band. ©2005 American Institute of Physics
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| 6. |
- Ketelhut, S., et al.
(author)
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gamma-Ray Spectroscopy at the Limits : First Observation of Rotational Bands in Lr-255
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:21, s. 212501-
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Journal article (peer-reviewed)abstract
- The rotational band structure of Lr-255 has been investigated using advanced in-beam gamma-ray spectroscopic techniques. To date, Lr-255 is the heaviest nucleus to be studied in this manner. One rotational band has been unambiguously observed and strong evidence for a second rotational structure was found. The structures are tentatively assigned to be based on the 1/2(-)[521] and 7/2(-)[514] Nilsson states, consistent with assignments from recently obtained alpha decay data. The experimental rotational band dynamic moment of inertia is used to test self-consistent mean-field calculations using the Skyrme SLy4 interaction and a density-dependent pairing force.
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| 7. |
- Al-Khatib, A, et al.
(author)
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Transition to non-collective states at high spin in Xe-124
- 2008
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In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 36:1, s. 21-29
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Journal article (peer-reviewed)abstract
- Excited states in Xe-124 were populated in the reaction Se-82(Ca-48, 6n) Xe-124 and gamma-ray coincidence relationships were measured with the Gammasphere spectrometer. Two new bands are observed and several of the previously known bands are extended in the high-as well as in the low-spin region. Two irregular high-spin structures are also added. The irregularities are a fingerprint of a transition from collective to non-collective behaviour. Configuration assignments to the new structures are proposed on the basis of systematics and by comparing experimental properties with calculations within the framework of the cranking model.
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