| 1. |
- Wadsworth, R., et al.
(författare)
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THE NORTHWEST FRONTIER : SPECTROSCOPY OF N similar to Z NUCLEI BELOW MASS 100
- 2009
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 40:3, s. 611-620
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Tidskriftsartikel (refereegranskat)abstract
- The spectroscopy and structure of excited states of N similar to Z nuclei in the mass 70-100 region has been investigated using two techniques. In the A similar to 70-80 region fusion evaporation reactions coupled with the recoil-beta-tagging method have been employed at Jyvaskyla to study low-lying states in odd-odd N = Z nuclei. Results from these and other data for known odd-odd nuclei above mass 60 will be discussed. In the heavier mass 90 region a fragmentation experiment has been performed using the RIS-ING/FRS setup at GSI. This experiment was primarily aimed at searching for spin gap isomers in nuclei around A similar to 96. The objectives of the latter experiment will be discussed.
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| 2. |
- Hinke, C. B., et al.
(författare)
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Superallowed Gamow-Teller decay of the doubly magic nucleus 100Sn
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 486:7403, s. 341-345
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Tidskriftsartikel (refereegranskat)abstract
- The shell structure of atomic nuclei is associated with 'magic numbers' and originates in the nearly independent motion of neutrons and protons in a mean potential generated by all nucleons. During beta(+)-decay, a proton transforms into a neutron in a previously not fully occupied orbital, emitting a positron-neutrino pair with either parallel or antiparallel spins, in a Gamow-Teller or Fermi transition, respectively. The transition probability, or strength, of a Gamow-Teller transition depends sensitively on the underlying shell structure and is usually distributed among many states in the neighbouring nucleus. Here we report measurements of the half-life and decay energy for the decay of Sn-100, the heaviest doubly magic nucleus with equal numbers of protons and neutrons. In the beta-decay of Sn-100, a large fraction of the strength is observable because of the large decay energy. We determine the largest Gamow-Teller strength so far measured in allowed nuclear beta-decay, establishing the 'superallowed' nature of this Gamow-Teller transition. The large strength and the low-energy states in the daughter nucleus, In-100, are well reproduced by modern, large-scale shell model calculations.
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| 3. |
- Wadsworth, R., et al.
(författare)
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Spin-gap Isomer in 96Cd
- 2012
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 381:1
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Tidskriftsartikel (refereegranskat)abstract
- Evidence has been obtained for the existence of the long predicted 16+ spin-gap isomer in 96Cd. The decay of the isomer was identified and studied following the use of an 850 MeV/u beam of 124Xe impinging on a Be target and the fragment recoil separator at the GSI Laboratory. Gamma decays from the fragments were detected using the RISING gamma ray array, in its stopped beam configuration, plus a silicon active stopper. The data obtained have been compared with shell model predictions, which indicate that the isoscalar neutron-proton interaction plays a key role in the formation of the isomer.
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| 4. |
- Al-Dahan, N., et al.
(författare)
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Isomeric States In 208Hg And 209Tl Populated In Fragmentation Of 238U
- 2009
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Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 40:3, s. 871-874
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Tidskriftsartikel (refereegranskat)abstract
- The nuclear structure of neutron-rich N > 126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A = 1 GeV U-238 beam on a Be target. The preliminary analysis indicates the presence of previously unreported isomeric states in the N = 128 isotones Hg-208 and Tl-209.
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| 5. |
- Al-Dahan, N., et al.
(författare)
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Nuclear Structure "Southeast" of 208Pb: Isomeric states in 208Hg and 209Tl
- 2009
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:6
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Tidskriftsartikel (refereegranskat)abstract
- The nuclear structure of neutron-rich N>126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A=1 GeV U-238 beam. Metastable states in the N=128 isotones Hg-208 and Tl-209 have been identified. Delayed gamma-ray transitions are interpreted as arising from the decay of I-pi=(8(+)) and (17/2(+)) isomers, respectively. The data allow for the so far most comprehensive verification of the shell-model approach in the region determined by magic numbers Z < 82 and N>126.
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| 6. |
- Blazhev, A, et al.
(författare)
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High-energy excited states in 98 Cd
- 2010
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Ingår i: Journal of Physics: Conference Series. ; 205:1
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Tidskriftsartikel (refereegranskat)abstract
- In 98 Cd a new high-energy isomeric γ -ray transition was identified, which confirms previous spin-parity assignments and enables for the first time the measurement of the E 2 and E 4 strength for the two decay branches of the isomer. Preliminary results on the 98 Cd high-excitation level scheme are presented. A comparison to shell-model calculations as well as implications for the nuclear structure around 100 Sn are discussed.
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| 7. |
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| 8. |
- Davies, P. J., et al.
(författare)
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The role of core excitations in the structure and decay of the 16(+) spin-gap isomer in Cd-96
- 2017
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 767, s. 474-479
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Tidskriftsartikel (refereegranskat)abstract
- The first evidence for beta-delayed proton emission from the 16(+) spin gap isomer in Cd-96 is presented. The data were obtained from the Rare Isotope Beam Factory, at the RIKEN Nishina Center, using the BigRIPS spectrometer and the EURICA decay station. beta p branching ratios for the ground state and 16(+) isomer have been extracted along with more precise lifetimes for these states and the lifetime for the ground state decay of Cd-95. Large scale shell model (LSSM) calculations have been performed and WKB estimates made for l = 0, 2, 4 proton emission from three resonance-like states in Ag-96, that are populated by the beta decay of the isomer, and the results compared to the new data. The calculations suggest that l = 2 proton emission from the resonance states, which reside similar to 5 MeV above the proton separation energy, dominates the proton decay. The results highlight the importance of core-excited wavefunction components for the 16(+) state.
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| 9. |
- Grawe, H., et al.
(författare)
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The (6+) isomer in 102Sn revisited : Neutron and proton effective charges close to the double shell closure
- 2021
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 820
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Tidskriftsartikel (refereegranskat)abstract
- In a high-energy fragmentation experiment at GSI an Iπ = (6+) isomer and its γ-decay are identified in 102Sn, the two-neutron neighbour of the doubly-magic 100Sn. Its half-life is measured to be T1/2 = 367(11) ns. The possible existence of further isomers is discussed in the framework of large-scale shell model (LSSM) calculations including up to five particle-hole excitations of the 100Sn core. From the precise B(E2; 6+ → 4+) strength and the recently remeasured value for B(E2; 8+ → 6+) in the two-proton hole neighbour 98Cd effective E2 polarization charges for protons and neutrons were inferred including LSSM corrections within the full N=4 0hω space. The results are discussed in comparison to predicted and empirically determined effective operators.
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| 10. |
- Haefner, G., et al.
(författare)
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Properties of γ-decaying Isomers in the 100Sn Region Revisited
- 2019
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Ingår i: Acta Physica Polonica B. - : JAGIELLONIAN UNIV PRESS. - 0587-4254 .- 1509-5770. ; 50:3, s. 431-437
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Tidskriftsartikel (refereegranskat)abstract
- The study of nuclei in the region around the N = Z doubly-magic nucleus 100Sn has been of long standing interest for the nuclear structure and nuclear astrophysics. Recently, Park et al. have reported on properties of γ-decaying isomers and isomeric ratios in the vicinity of 100Sn. That experiment was performed at the Radioactive Ion Beam Factory (RIBF) of the RIKEN Nishina Center in Japan as a part of the EURICA campaign. Neutron-deficient nuclei were produced in a fragmentation reaction of a 124Xe primary beam on a 9Be target at an energy of 345 MeV/A. Secondary ions were separated and identified in the BigRIPS fragment separator and implanted in the silicon detector array WAS3ABi. The data presented here were obtained in another experiment performed at the RIBF using the same reaction but slightly different separator settings. New results of ratios of isomeric population and half-lives of γ-decaying isomers populated in the experiment are presented.
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