| 1. |
- Maierbeck, P., et al.
(författare)
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Structure of 55Ti from relativistic one-neutron knockout
- 2009
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 675:1, s. 22-27
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Tidskriftsartikel (refereegranskat)abstract
- Results are presented from a one-neutron knockout reaction at relativistic energies on 56Ti using the GSI FRS as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive and exclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the orbital angular momentum of the populated states. First-time observation of the 955(6) keV -hole state in 55Ti is reported. The measured data for the first time proves that the ground state of 55Ti is a 1/2- state, in agreement with shell-model calculations using the GXPF1A interaction that predict a sizable N=34 gap in 54Ca.
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| 2. |
- Maierbeck, P., et al.
(författare)
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Probing the single particle structure around Ca-54 with one-neutron knock-out
- 2008
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Ingår i: AIP Conference Proceedings. - 1551-7616 .- 0094-243X. ; 1012, s. 89-93
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Konferensbidrag (refereegranskat)abstract
- The nuclei Ca-47 and Ti-55 were populated in one-neutron knock-out reactions at relativistic energies. Momentum distributions of the residual nuclei as well as gamma-ray spectra were measured at the GSI fragment separator (FRS). Preliminary results of the ongoing analysis including cross sections and spin/parity assignments are presented.
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| 3. |
- Fynbo, H. O. U., et al.
(författare)
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The β-decay approach for studying 12C
- 2008
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 111:1
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Tidskriftsartikel (refereegranskat)abstract
- The β-decays of the mirror nuclei 12B and 12N both populate states in 12C and they are therefore a precious source of information about this nucleus. Due to the selection rules of β-decay only 0+, 1+ and 2+ states are populated. This allows a very clean study of unbound states just above the 3α-threshold with those spin and parities. This probe has been applied in two experiments using two complementary experimental techniques: in the first the three α-particles emitted after β-decay are measured in coincidence in separate detectors using the ISOL method, while in the second method 12B and 12N are implanted in a detector and the summed energy of the three α-particles is measured directly. Preliminary results from the two approaches are presented. © 2008 IOP Publishing Ltd.
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| 4. |
- Hyldegaard, S., et al.
(författare)
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Precise branching ratios to unbound 12C states from 12N and 12B [beta]-decays
- 2009
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 678:5, s. 459 - 464
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Tidskriftsartikel (refereegranskat)abstract
- Two complementary experimental techniques have been used to extract precise branching ratios to unbound states in 12C from 12N and 12B [beta]-decays. In the first the three [alpha]-particles emitted after [beta]-decay are measured in coincidence in separate detectors, while in the second method 12N and 12B are implanted in a detector and the summed energy of the three [alpha]-particles is measured directly. For the narrow states at 7.654 MeV (0+) and 12.71 MeV (1+) the resulting branching ratios are both smaller than previous measurements by a factor of [similar, equals]2. The experimental results are compared to no-core shell model calculations with realistic interactions from chiral perturbation theory, and inclusion of three-nucleon forces is found to give improved agreement.
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| 5. |
- Hyldegaard, S., et al.
(författare)
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STUDIES OF C-12 USING beta-DECAYS
- 2008
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Ingår i: International Journal of Modern Physics E. - 0218-3013. ; 17:10, s. 2182-2187
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Konferensbidrag (refereegranskat)abstract
- The nuclear structure of states in C-12 have been a subject of interest for both theory and experiment since the early days of nuclear physics. Many open questions remain, especially concerning the existence and properties of 0(+) and 2(+) states in the triple alpha continuum. A series of experiments have been performed using beta-decay of N-12 and B-12 to probe these states. The latest experiment was performed at KVI using an implantation method, measuring the sum energy of the three alpha-particles directly. Preliminary results from this experiment will be presented.
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| 6. |
- Niedermaier, O., et al.
(författare)
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"Safe" Coulomb excitation of Mg-30
- 2005
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 94:17, s. 172501 (artno)-
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg-30 ions accelerated to an energy of 2.25 MeV/u together with a thin Ni-nat target, Coulomb excitation of the first excited 2(+) states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation γ-ray yields the B(E2;0(gs)(+)→ 2(1)(+)) value of Mg-30 was determined to be 241(31)e(2) fm(4). Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope Mg-30 resides outside the "island of inversion."
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| 7. |
- Niedermaier, O., et al.
(författare)
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The neutron-rich Mg isotopes: first results from MINIBALL at REX-ISOLDE
- 2005
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 752, s. 273-273
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg-30 ions accelerated to an energy of 2.25 MeV/u together with a thin Ni-nat target, Coulomb excitation of the first excited 2(+) states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation γ-ray yields the B(E2;0(gs)(+)→ 2(1)(+)) value of Mg-30 was determined to be 241(31)e(2) fm(4). Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope Mg-30 resides outside the "island of inversion."
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| 8. |
- Scheit, H., et al.
(författare)
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Coulomb excitation of neutron-rich beams at REX-ISOLDE
- 2005
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 25:Suppl. 1, s. 397-402
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Konferensbidrag (refereegranskat)abstract
- After the successful commissioning of the radioactive beam experiment at ISOLDE (REX-ISOLDE) - an accelerator for exotic nuclei produced by ISOLDE - in 2002 and the promotion to a CERN user facility in 2003, first physics experiments using these beams were performed. Initial experiments focused on the region of deformation in the vicinity of the neutron-rich Na and Mg isotopes. Preliminary results on the neutron-rich Na and Mg isotopes show the high potential and physics opportunities offered by the exotic isotope accelerator REX in conjunction with the modern Germanium gamma spectrometer MINIBALL.
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| 9. |
- Stefanescu, I., et al.
(författare)
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Coulomb Excitation of 68,70Cu: First Use of Postaccelerated Isomeric Beams
- 2007
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Ingår i: Physical Review Letters. ; 98
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first low-energy Coulomb excitation measurements with radioactive Ipi=6- beams of odd-odd nuclei 68,70Cu. The beams were produced at ISOLDE, CERN and were post-accelerated by REX-ISOLDE to 2.83 MeV/nucleon. gamma rays were detected with the MINIBALL spectrometer. The 6- beam was used to study the multiplet of states (3-, 4-, 5-, 6-) arising from the pi2p3/2nu1g9/2 configuration. The 4- state of the multiplet was populated via Coulomb excitation and the B(E2;6--->4-) value was determined in both nuclei. The results obtained illustrate the fragile stability of the Z=28 shell and N=40 subshell closures. A comparison with large-scale shell-model calculations using the 56Ni core shows the importance of the proton excitations across the Z=28 shell gap to the understanding of the nuclear structure in the neutron-rich nuclei with N[approximate]40.
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| 10. |
- Diget, C. A., et al.
(författare)
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Breakup channels for C-12 triple-alpha continuum states
- 2009
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 80:3
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Tidskriftsartikel (refereegranskat)abstract
- The triple-alpha-particle breakup of states in the triple-alpha continuum of C-12 has been investigated by way of coincident detection of all three alpha particles of the breakup. The states have been fed in the beta decay of N-12 and B-12, and the alpha particles measured using a setup that covers all of the triple-alpha phase space. Contributions from the breakup through the Be-8(0(+)) ground state as well as other channels-interpreted as breakup through excited energies in Be-8-have been identified. Spins and parities of C-12 triple-alpha continuum states are deduced from the measured phase-space distributions for breakup through Be-8 above the ground state by comparison to a fully symmetrized sequential R-matrix description of the breakup. At around 10 MeV in C-12, the breakup is found to be dominated by 0(+) strength breaking up through the ghost of the Be-8(0(+)) ground state with L = 0 angular momentum between the first emitted alpha particle and the intermediate Be-8 nucleus. For C-12 energies above the 12.7 MeV 1(+) state, however, L = 2 breakup of a C-12 2(+) state through the Be-8(2(+)) excited state dominates. Furthermore, the possibility of a 2(+) excited state in the 9-12 MeV region of C-12 is investigated.
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