| 1. |
- Sylvan, G N, et al.
(författare)
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Deformation driving intruder orbitals in Kr-77
- 1997
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 56:2, s. 772-781
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Kr-77 were identified via analysis of prompt gamma-gamma coincidences in the Ni-58(Si-29,2 alpha 2p) reaction at 128 MeV at the Gammasphere facility. Evaporation channel selection was achieved using the 95 element Microball charged-particle detector. 27 new states and 42 new transitions were found, The positive-parity bands were confirmed and the alpha=-1/2 band extended to 39/2(+). The negative-parity signature pair was extended to 31/2(-) and 37/2(-). Two new high-lying negative-parity bands were found extending from a state of spin I = 15/2 and energy 2.6 MeV to 17.4 MeV at I = (55/2). The new bands appear highly deformed and become yrast at high spin. A three-quasiparticle structure based on deformation driving, low-K unique-parity and intruder orbitals is suggested for them.
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| 2. |
- Rudolph, Dirk, et al.
(författare)
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Shell-model Influence in the Rotational Nucleus 86Mo
- 1996
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 54:1, s. 117-124
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Mo-86 were studied by means of the fusion evaporation reaction Ni-58(S-32,2p2n) Mo-86 at 135 MeV beam energy. Charged-particle-gamma gamma and -gamma gamma gamma coincidences recorded with the early implementation of the GAMMASPHERE array and the MICROBALL charged-particle detection system were used to largely extend the level scheme of the T-tau=1 nucleus Mo-86 to a possible spin of I=24h at 13 MeV excitation energy. The excitation scheme is compared to neighboring nuclei. There is evidence for enhanced shell-model influence in the 4 quasiparticle region (I=12-16h). The observed (pi=+,alpha=0) sequence at spin I greater than or equal to 16 h appears to be associated with a triaxial collective rotational band. This interpretation is supported by calculations within the configuration-dependent shell-correction approach with the cranked Nilsson potential.
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| 3. |
- Sun, H., et al.
(författare)
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New Band Structures and an Unpaired Crossing in 78Kr
- 1999
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 59:2, s. 655-664
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Kr-78 were studied using the Ni-58(Na-23,3p) reaction at 70 MeV and the Ni-58(Si-23,alpha 4p) reaction at 130 MeV. Prompt gamma-gamma coincidences were measured using the Pitt-FSU detector array and the GAMMASPHERE-MICROBALL array. Results from these experiments have led to 26 new excitation levels, some of which have been grouped into 3 new bands. Spins were assigned based on directional correlations of oriented nuclei. Two of the new negative-parity bands appear to form a signature-partner pair based on a two-quasineutron structure, in contrast to the previously known two-quasiproton negative-parity bands. A forking has been observed at the 24(+) state in the yrast band, which calculations suggest may result from an unpaired crossing. The available evidence suggests oblate shapes in the yrast band coexist with prolate shapes in the negative-parity bands. [S0556-2813(99)04602-6].
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| 4. |
- CRISTANCHO, F, et al.
(författare)
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MULTIPLE SUPERDEFORMED BANDS IN SR-81
- 1995
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Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 357:3, s. 281-286
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Tidskriftsartikel (refereegranskat)abstract
- Four superdeformed bands extending over five to twelve transitions have been identified in Sr-81 from a study With the Gammasphere array and the Microball charged-particle array, One of the bands shows an upbend in the dynamic moment of inertia at a rotational frequency of 1.2 MeV and all bands exhibit a nearly constant moment of inertia below that frequency.
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| 5. |
- JIN, HQ, et al.
(författare)
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IDENTIFICATION AND QUADRUPOLE-MOMENT MEASUREMENT OF A SUPERDEFORMED BAND IN ZR-84
- 1995
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 75:8, s. 1471-1474
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Zr-84 were studied using the early implementation phase of the Gammasphere array and the ''Microball'' charged-particle detector system. A cascade of nine gamma rays with a dynamic moment of inertia which is characteristic of superdeformed rotational bands in the A = 80 region has been identified and assigned to Zr-84. The measured transition quadrupole moment of the band corresponds to a prolate quadrupole deformation of beta(2) = 0.53 and confirms the superdeformed nature of this band. This is the first direct experimental confirmation of the existence of the predicted superdeformed shell gap at N similar or equal to 44 particle number.
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| 6. |
- LAFOSSE, DR, et al.
(författare)
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CHARACTERIZATION OF THE FIRST SUPERDEFORMED BAND IN THE A-APPROXIMATE-TO-80 REGION
- 1995
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Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 354:1-2, s. 34-40
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Tidskriftsartikel (refereegranskat)abstract
- The recently discovered superdeformed band in one of the strontium isotopes has been identified as belonging to Sr-83 from a study with the Gammasphere array and the Microball charged-particle detector system. From its decay pattern, a spin of (81 +/- 2)/2 ($) over bar h is deduced for the highest level of this band. Evidence for very fast transition rates and agreement of the characteristics of this band with the theoretical predictions establish the yrast superdeformed nature of this band in Sr-83.
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