| 1. |
- Evans, AO, et al.
(författare)
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High-spin structure beyond band termination in Er-157
- 2004
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Ingår i: Physical Review Letters. - 1079-7114. ; 92:25
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Tidskriftsartikel (refereegranskat)abstract
- The angular-momentum induced transition from a deformed state of collective rotation to a noncollective configuration has been studied. In Er-157 this transition manifests itself as favored band termination near I=45 (h) over bar. The feeding of these band terminating states has been investigated for the first time using the Gammasphere spectrometer. Many weakly populated states lying at high excitation energy that decay into these special states have been discovered. Cranked Nilsson-Strutinsky calculations suggest that these states arise from weakly collective "core-breaking" configurations.
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| 2. |
- Evans, AO, et al.
(författare)
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High-spin structure in Er-157 up to and above band termination
- 2006
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 73:6
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Tidskriftsartikel (refereegranskat)abstract
- The high-spin structure of Er-157 has been greatly expanded using the Gammasphere spectrometer to investigate the Cd-114(Ca-48,5n) reaction at 215 MeV. Many new transitions have been placed in a greatly augmented level scheme up to spin 40h with many collective rotational sequences established. With increasing angular momentum, this nucleus undergoes a Coriolis-induced shape transition from a deformed state of collective rotation to a noncollective configuration. This transition manifests itself as favored band termination near I=45h in three rotational structures. Many weakly populated states lying at high excitation energy that decay into the terminating states have been discovered. Cranked-Nilsson-Strutinsky calculations suggest that the levels that feed the terminating states arise from weakly collective configurations that break the Z=64 semimagic core.
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| 3. |
- Evans, AO, et al.
(författare)
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Magnetic properties of smooth terminating dipole bands in Te-110,Te-112
- 2006
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 636:1, s. 25-30
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Tidskriftsartikel (refereegranskat)abstract
- Three strongly coupled sequences have been established in Te-110,Te-112 up to high spins. They are interpreted in terms of deformed structures built on proton 1-particle-1-hole excitations that reach termination at I similar to 40h. This is the first observation of smooth terminating dipole structures in this mass region. Lifetime measurements have allowed the extraction of experimental B(M 1; 1 -> I - 1) and B(E2; I -> I - 2) reduced transition rates for one of the dipole bands in Te-110. The results support the deformed interpretation. (c) 2006 Elsevier B.V. All rights reserved.
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| 4. |
- ASZTALOS, SJ, et al.
(författare)
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CONFIRMATION OF THE SUPERDEFORMED BAND IN PB-192
- 1995
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Ingår i: Zeitschrift für Physik A Hadrons and Nuclei. - 0939-7922 .- 1431-5831. ; 352:3, s. 239-240
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Pb-192 were populated via the reaction Yb-173(Mg-24,5n) at a beam energy of 140 MeV, and the resulting gamma-rays were deteced using GAMMA-SPHERE. A previously observed superdeformed band in Pb-192 has been confirmed.
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| 5. |
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| 6. |
- BERNSTEIN, LA, et al.
(författare)
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ONSET OF COLLECTIVITY IN NEUTRON-DEFICIENT PO-196,PO-198
- 1995
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 52:2, s. 621-627
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Tidskriftsartikel (refereegranskat)abstract
- We have studied via in-beam gamma-ray spectroscopy Po-196 and Po-198, which are the first neutron-deficient Po isotopes to exhibit a collective low-lying structure. The ratios of yrast state energies and the E2 branching ratios of transitions from non-yrast to yrast states are indicative of a low-lying vibrational structure. The onset of collective motion in these isotopes can be attributed to the opening of the neutron i(13/2) orbital at N approximate to 112 and the resulting large overlap between the two valence protons in the h(9/2) orbital and the valence neutrons in the i(13/2) orbital.
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| 7. |
- BERNSTEIN, LA, et al.
(författare)
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SUPERDEFORMATION IN ER-154
- 1995
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 52:3, s. R1171-R1174
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Tidskriftsartikel (refereegranskat)abstract
- A superdeformed (SD) band consisting of 13 gamma-ray transitions has been observed in Er-154, an isotone of Dy-152(66). The experiment was performed using the Sn-118(Ar-40,4n) reaction at E(Ar-40)=185 MeV and the early implementation of GAMMASPHERE. This is an observation of a SD band in the A approximate to 150 region with a proton number greater than 66. The J((2)) moment of inertia of the band is constant above ($) over bar h omega=0.45 MeV and shows a sharp rise below this value suggesting a paired band crossing. These results suggest that total Routhian surface calculations fail to accurately predict the deformation of the band.
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| 8. |
- Cederwall, Bo, et al.
(författare)
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MEASUREMENT OF ULTRA-FAST GAMMA-RAY TRANSITIONS FROM HEAVY-ION COMPOUND NUCLEUS REACTIONS
- 1995
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 354:2-3, s. 591-594
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Tidskriftsartikel (refereegranskat)abstract
- A method for correcting target-thickness-induced Doppler broadening in gamma-ray spectra from weakly populated, very short-lived (femtosecond) states is presented. The method is illustrated by an analysis of superdeformed transitions in Dy-152,Dy-153 for which the validity of the procedure could be verified consistently from previous lifetime measurements in Dy-152. Furthermore, estimates of the superdeformed lifetimes, previously not measured in Dy-153, are obtained.
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| 9. |
- Cederwall, Bo, et al.
(författare)
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NEW FEATURES OF SUPERDEFORMED BANDS IN HG-194
- 1994
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 72:20, s. 3150-3153
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Tidskriftsartikel (refereegranskat)abstract
- Two new features of superdeformed (SD) bands in the A almost-equal-to 190 region emerge from a study of Hg-194 with the Gammasphere detector array. A decrease of the dynamic moment of inertia is observed for rotational frequencies HBARomega greater-than-or-equal-to 0.4 MeV, confirming long standing expectations based on mean field calculations with pairing. Evidence for a small staggering in the SD transition energies is also observed, suggesting the presence of terms with fourfold symmetry in the SD Hamiltonian.
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| 10. |
- Cederwall, Bo, et al.
(författare)
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NEW OBLATE BAND IN HG-196 WITH QUENCHED M1 STRENGTH
- 1993
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 47:6, s. R2443-R2446
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in the nucleUs Hg-196 were populated in the reaction (Os(Be,5n))-Os-192 at a beam energy of 65 MeV. A regular rotational-like DELTAI = 1 band has been observed up to an excitation energy of E* almost-equal-to 8.7 MeV and spin I almost-equal-to 30hBAR. This is the second observation of a band of this character in a mercury isotope. The experimental results are compared with mean field calculations and semiclassical estimates based on the Donau-Frauendorf formalism. The mercury bands show significantly lower B(M1)/B(E2) branching ratios as compared with similar bands in light lead nuclei. This difference may be more readily explained by a difference in single-particle structure rather than by large differences in deformation between the lead and mercury configurations.
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