| 1. |
- Vogt, A., et al.
(författare)
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Isomers and high-spin structures in the N=81 isotones Xe-135 and Ba-137
- 2017
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Ingår i: PHYSICAL REVIEW C. - : AMER PHYSICAL SOC. - 2469-9985. ; 95:2
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Tidskriftsartikel (refereegranskat)abstract
- The high-spin structures and isomers of the N = 81 isotones Xe-135 and Ba-137 are investigated after multinucleon-transfer (MNT) and fusion-evaporation reactions. Both nuclei are populated (i) in Xe-136+ U-238 and (ii) Xe-136+ Pb-208 MNT reactions employing the high-resolution Advanced Gamma Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA, (iii) in the Xe-136+ Pt-198 MNT reaction employing the gamma-ray array GAMMASPHERE in combination with the gas-detector array CHICO, and (iv) via a B-11+ Te-130 fusion-evaporation reaction with the HORUS gamma-ray array at the University of Cologne. The high-spin level schemes of Xe-135 and Ba-137 are considerably extended to higher energies. The 2058-keV (19/2(-)) state in Xe-135 is identified as an isomer, closing a gap in the systematics along the N = 81 isotones. Its half-life is measured to be 9.0(9) ns, corresponding to a reduced transition probability of B(E2,19/2(-) -> 15/2(-)) = 0.52(6) W.u. The experimentally deduced reduced transition probabilities of the isomeric states are compared to shell-model predictions. Latest shell-model calculations reproduce the experimental findings generally well and provide guidance to the interpretation of the new levels.
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| 2. |
- Vogt, A., et al.
(författare)
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High-spin structure of Xe-134
- 2016
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Ingår i: PHYSICAL REVIEW C. - 2469-9985. ; 93:5
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Tidskriftsartikel (refereegranskat)abstract
- Detailed spectroscopic information on the N similar to 82 nuclei is necessary to benchmark shell-model calculations in the region. The nuclear structure above long-lived isomers in Xe-134 is investigated after multinucleon transfer (MNT) and actinide fission. Xenon-134 was populated as (i) a transfer product in Xe-136 + U-238 and Xe-136 + Pb-208 MNT reactions and (ii) as a fission product in the Xe-136 + U-238 reaction employing the high-resolution Advanced Gamma Tracking Array (AGATA). Trajectory reconstruction has been applied for the complete identification of beamlike transfer products with the magnetic spectrometer PRISMA. The Xe-136 + Pt-198 MNT reaction was studied with the gamma-ray spectrometer GAMMASPHERE in combination with the gas detector array Compact Heavy Ion Counter (CHICO). Several high-spin states in Xe-134 on top of the two long-lived isomers are discovered based on gamma gamma-coincidence relationships and information on the gamma-ray angular distributions as well as excitation energies from the total kinetic energy loss and fission fragments. The revised level scheme of Xe-134 is extended up to an
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| 3. |
- Caceres, L., et al.
(författare)
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Nuclear structure studies of F-24
- 2015
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 92:1
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Tidskriftsartikel (refereegranskat)abstract
- The structure of the F-24 nucleus has been studied at GANIL using the beta decay of O-24 and the in-beam.-ray spectroscopy from the fragmentation of Na-27,Na-28, Ne-25,Ne-26, and Mg-29,Mg-30 nuclei. Combining these complementary experimental techniques, the level scheme of F-24 has been constructed up to 3.6 MeV by means of particle-gamma and particle-gamma gamma coincidence relations. Experimental results are compared to shell-model calculations using the standard USDA and USDB interactions as well as ab initio valence-space Hamiltonians calculated from the in-medium similarity renormalization group based on chiral two- and three-nucleon forces. Both methods reproduce the measured level spacings well, and this close agreement allows unidentified spins and parities to be consistently assigned.
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| 4. |
- Stanoiu, M., et al.
(författare)
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Study of neutron rich carbon and oxygen nuclei up to drip line
- 2004
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 746, s. 135C-139C
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Tidskriftsartikel (refereegranskat)abstract
- In-beam gamma-spectroscopy using fragmentation reactions of radioactive beams have been performed in order to study the structure of excited states in neutron rich oxygen and carbon isotopes. For the produced fragments, gamma-ray energies, intensities and gamma-gamma coincidences have been measured. The experiment was performed at GANIL. New gamma-lines have been identified and placed in level schemes for C17-20. The non observation of any gamma-ray in O-23,O-24 suggests that their first excited states lie above the neutron threshold. These results are discussed in the framework of shell model calculations.
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| 5. |
- Mason, P, et al.
(författare)
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Octupole signatures in Ba-124,Ba-125
- 2005
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Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. S1729-S1733
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Tidskriftsartikel (refereegranskat)abstract
- The gamma decay of the nuclei Ba-121,Ba-125 has been investigated with the EUROBALL array, using the reaction Ni-64+Ni-64 at E-beam = 255 and 261 MeV. Six new E1 transitions have been found in the nucleus Ba-125, suggesting a significant role of octupole correlations in the origin of its parity doublets. The J(pi) = 3(-) level of the nucleus Ba-124 has been identified for the first time. Its excitation energy is in very good agreement with a prediction based on a microscopic model including octupole interactions.
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| 6. |
- Sohler, D., et al.
(författare)
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Yrast states of the proton drip line nucleus 106 Sb
- 1999
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993 .- 0556-2813 .- 1089-490X. ; 59:3, s. 1324-1327
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Tidskriftsartikel (refereegranskat)abstract
- Yrast states of [Formula Presented] have been investigated in the [Formula Presented] reaction using in-beam [Formula Presented]-spectroscopic methods and in the [Formula Presented] reaction performing delayed [Formula Presented] and conversion electron studies. A new isomeric state was found at 103 keV with [Formula Presented] The number of states and transitions in the proposed level scheme have been doubled. The experimental results are discussed within the framework of the shell model. © 1999 The American Physical Society.
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| 7. |
- Stanoiu, M., et al.
(författare)
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Disappearance of the N=14 shell gap in the carbon isotopic chain
- 2008
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 78:3
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Tidskriftsartikel (refereegranskat)abstract
- The structure of C-17-20(6) nuclei was investigated by means of the in-beam gamma-ray spectroscopy technique using fragmentation reactions of radioactive beams. Based on particle-gamma and particle-gamma gamma coincidence data, level schemes are constructed for the neutron-rich C17-20 nuclei. The systematics of the first excited 2(+) states in the carbon isotopes is extended for the first time to A = 20 showing that in contrast to the case of the oxygen isotopes, the N = 14 subshell closure disappears. Experimental results are compared with shell-model calculations. Agreement between them is found only if a reduced neutron-neutron effective interaction is used. Implications of this reduced interaction in some properties of weakly bound neutron-rich Carbon are discussed.
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| 8. |
- Stanoiu, M., et al.
(författare)
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Spectroscopy of (26)F
- 2012
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 85:1, s. 017303-
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Tidskriftsartikel (refereegranskat)abstract
- The structure of the weakly bound (26)(9)F(17) odd-odd nucleus, produced from (27,28)Na nuclei, has been investigated at GANIL by means of the in-beam gamma-ray spectroscopy technique. A single gamma-line is observed at 657(7) keV in (26)(9)F which has been ascribed to the decay of the excited J = 2(+) state to the J = 1(+) ground state. The possible presence of intruder negative parity states in (26)F is also discussed.
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| 9. |
- Stanoiu, M., et al.
(författare)
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Study of drip line nuclei through two-step fragmentation
- 2004
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 20:1, s. 95-96
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the structure of light neutron-rich nuclei around N = 16 by employing the in-beam gamma-ray spectroscopy technique using the fragmentation of secondary beams of Ne-25,Ne-26, Na-27,Na-28 and Mg-29,Mg-30 isotopes. This secondary-beam cocktail was obtained by the fragmentation of a 36 S beam at 77.5 MeV.A by the SISSI/GANIL facility. By a second-step fragmentation, we have measured gamma-ray-residue coincidences in C17-20 and O-23,O-24 and described the obtained levels in the framework of the shell model.
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| 10. |
- Vajta, Zs., et al.
(författare)
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Excited states in the neutron-rich nucleus F-25
- 2014
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 89:5, s. 054323-
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Tidskriftsartikel (refereegranskat)abstract
- The structure of the nucleus F-25(9) was investigated through in-beam. gamma-ray spectroscopy of the fragmentation of Ne-26 and Na-27,Na-28 ion beams. Based on the particle-gamma and particle-gamma gamma coincidence data, a level scheme was constructed and compared with shell model and coupled-cluster calculations. Some of the observed states were interpreted as quasi-single-particle states built on top of the closed-shell nucleus O-24, while the others were described as states arising from coupling of a single proton to the 2(broken vertical bar) core excitation of O-24.
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