| 1. |
- Caballero, O L, et al.
(författare)
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"Complete" High-Spin Structure of 57Co
- 2003
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Ingår i: Physical Review C: covering nuclear physics. ; 67
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Tidskriftsartikel (refereegranskat)abstract
- A comprehensive high-spin decay scheme has been deduced for 57Co using the Gammasphere Germanium detector array coupled to the 4π charged-particle detector system Microball. Following the fusion-evaporation reaction of 28Si(36Ar,1α3p)57Co at 136 MeV beam energy about 90 excited states have been observed in 57Co, which are connected by some 230 γ-ray transitions. The proposed level scheme reaches 16 MeV excitation energy at a spin of 17ħ–18ħ. With its complexity the level scheme of 57Co appears to be “complete” up to 1 or 2 MeV above the yrast line. This aspect is further investigated through a comparison of the data with spherical shell-model calculations.
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| 2. |
- Fischer, S M, et al.
(författare)
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Alignment additivity in the two-quasiparticle superdeformed bands of Tl-192
- 1996
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 53:5, s. 2126-2133
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Tidskriftsartikel (refereegranskat)abstract
- Four superdeformed bands have been confirmed in Tl-192. Two of these bands have T-(2) dynamic moments of inertia which are nearly constant with rotational frequency HBAR omega. The other two bands show the characteristic rise of T-(2) with increasing HBAR omega seen in most superdeformed bands of the A = 190 region of superdeformation. From comparisons with the odd-A neighbors, it was found that the alignments of these bands relative to a Hg-192 core can be accounted for from the additive contributions of the assigned quasiproton and quasineutron orbitals.
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| 3. |
- Riley, M. A., et al.
(författare)
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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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Ingår i: Physica Scripta. - 0031-8949. ; T125, s. 123-126
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Yadav, R. B., et al.
(författare)
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Identification of triaxial strongly deformed bands in Hf-168
- 2008
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 78:4
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Tidskriftsartikel (refereegranskat)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. |
- Bark, R A, et al.
(författare)
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Coexistence of triaxial and prolate shapes in Ir-171
- 1999
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Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 657:2, s. 113-133
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in Ir-171 have been observed for the first time. Gamma-rays were assigned to the nucleus by the recoil-decay tagging method, The ground-state band has a structure consistent with an h(11/2) proton coupled to a core of large triaxial deformation. At high spins, a bandcrossing occurs which is interpreted as a change in shape to a prolate deformation, Band-mixing calculations are performed for Ir171-175. These show that shape-coexistence between triaxial and prolate states in these nuclei follows the same systematics found in their Pt and Os neighbours. The systematics are also compared with deformations calculated for Ir171-179 using the code "Ultimate Cranker". Dipole bands were also observed, but tilted axis cranking calculations suggest that they are associated with a collective rotation.
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| 6. |
- Hartley, D. J., et al.
(författare)
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Persistence of collective behavior at high spin in the N=88 nucleus Tb-153
- 2015
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 91:5
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in the N = 88 nucleus Tb-153 were observed up to spin similar to 40 in an experiment utilizing the Gammasphere array. The Tb-153 states were populated in a weak alpha 4n evaporation channel of the Cl-37 + Sn-124 reaction. Two previously known sequences were extended to higher spins, and a new decoupled structure was identified. The pi h(11/2) band was observed in the spin region where other N = 88 isotopes exhibit effects of prolate to oblate shape changes leading to band termination along the yrast line, whereas Tb-153 displays a persistent collective behavior. However, minor perturbations of the very highest state in both signatures of this h(11/2) band are observed, which perhaps signal the start of the transition towards band termination.
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| 7. |
- Hartley, D. J., et al.
(författare)
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Wobbling mode in Ta-167
- 2009
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:4
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Tidskriftsartikel (refereegranskat)abstract
- The collective wobbling mode, the strongest signature for the rotation of a triaxial nucleus, has previously been seen only in a few Lu isotopes in spite of extensive searches in nearby isotopes. A sequence of transitions in the N = 94 Ta-167 nucleus exhibiting features similar to those attributed to the wobbling bands in the Lu nuclei has now been found. This band feeds into the pi i(13/2) band at a relative energy similar to that seen in the established wobbling bands and its dynamic moment of inertia and alignment properties are nearly identical to the i(13/2) structure over a significant frequency range. Given these characteristics, it is likely that the wobbling mode has been observed for the first time in a nucleus other than Lu, making this collective motion a more general phenomenon.
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| 8. |
- Marsh, J. C., et al.
(författare)
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Identification of triaxial strongly deformed bands in Hf-164
- 2013
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 88:4
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Tidskriftsartikel (refereegranskat)abstract
- Two new rotational bands of distinct character have been identified in Hf-164. They are suggested to correspond to the long-anticipated triaxial strongly deformed (TSD) bands predicted by theoretical studies. The bands have been linked to known states, and the level spins and energies could be determined. The bands are also substantially stronger in intensity and are located at lower spins than the previously observed TSD bands in Hf-168, hereby making Hf-164 the best even-even system so far for the study of TSD structures in the A similar to 160 mass region. Cranking calculations based on the modified-oscillator model suggest that the bands are associated with four-quasiparticle configurations that involve high-j intruder (i(13/2))(2) proton orbitals.
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| 9. |
- Ragnarsson, I., et al.
(författare)
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Statistical analysis of pairs of rotational bands in "odd and even" nuclei at normal deformation
- 1995
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Ingår i: Physics Letters B. - 0370-2693. ; 356:4, s. 423-428
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Tidskriftsartikel (refereegranskat)abstract
- A statistical analysis has been done for the variation of the moment of inertia in pairs of rotational bands between odd-A and adjacent A - 1 even-even nuclei at normal deformation. A smooth distribution centered at small differences or no difference is obtained but apart from this, no special surplus of so-called identical bands is found. Furthermore, it is found that upsloping orbitals are predominantly involved when forming bands with similar moments of inertia.
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| 10. |
- Riley, M A, et al.
(författare)
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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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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. 1735-1740
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Tidskriftsartikel (refereegranskat)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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