| 1. |
- Bergmann, U.C., et al.
(författare)
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On the b-decay of 9C
- 2001
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Ingår i: Nuclear Physics A. ; 692:3-4, s. 427-450
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Tidskriftsartikel (refereegranskat)abstract
- In β-decay experiments on 9C at CERN/ISOLDE the β-strength was determined to the ground state, the 12.2 MeV excited state and the Isobaric Analog State (IAS) at 14.655 MeV in 9B. A large β-strength asymmetry is deduced for the mirror transitions of 9C and 9Li to states around 12 MeV excitation energy. A satisfactory description of the three-body decay from a narrow energy region around the 12.2 MeV resonance is obtained within a sequential model involving the ground and first-excited states of 5Li and 8Be. From the study of angular correlations the spin of the 12.2 MeV state is determined as 5/2−. For the first time the population of the IAS is observed in β-decay and new information on the decay of this state is obtained. The advantages of a closely packed, highly segmented detector setup are demonstrated.
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| 2. |
- Fynbo, H. O. U., et al.
(författare)
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The beta 2p decay mechanism of Ar-31
- 2000
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Ingår i: Nuclear Physics A. - 0375-9474. ; 677, s. 38-60
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the beta-decay of Ar-31 with a high granularity setup sensitive to multiparticle decay branches. Two-proton emission is observed from the isobaric analog state in Cl-31 to the four lowest states in P-29 and furthermore from a large number of states fed in Gamow-Teller transitions. The mechanism of two-proton emission is studied via energy and angular correlations between the two protons. In all cases the mechanism is found to be sequential yielding information about states in S-30 up to 8 MeV excitation energy. Improved data on the beta-delayed one-proton branches together with the two-proton data provide precise information about the beta-strength distribution up to 15 MeV excitation energy.
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| 3. |
- Markenroth, Karin, 1973, et al.
(författare)
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Crossing the dripline to N-11 using elastic resonance scattering
- 2000
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 6203:3
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Tidskriftsartikel (refereegranskat)abstract
- The level structure of the unbound nucleus N-11 has been studied by C-10+p elastic resonance scattering in inverse geometry with the LISE3 spectrometer at GANIL, using a C-10 beam with an energy of 9.0 MeV/ nucleon. An additional measurement was done at the A1200 spectrometer at MSU. The excitation function above the C-10+p threshold has been determined up to 5 MeV. A potential-model analysis revealed three resonance states at energies 1.27(-0.05)(+0.18) MeV (Gamma = 1.44 +/- 0.2 MeV), 2.01(-0.05)(+0.15) MeV (Gamma = 0.84 +/- 0.2 MeV), and 3.75 +/- 0.05 MeV (Gamma = 0.60 +/- 0.05 MeV) with the spin-parity assignments I-pi=1/2+,1/2,-,5/2+, respectively. Hence, N-11 is shown to have a ground state parity inversion completely analogous to its mirror partner Be-11. A narrow resonance in the excitation function at 4.33 +/- 0.05 MeV was also observed and assigned spin parity 3/2-.
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| 4. |
- Bergmann, U. C., et al.
(författare)
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On the beta-decay of C-9
- 2001
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Ingår i: Nuclear Physics A. - 0375-9474. ; 692:3-4, s. 427-450
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Tidskriftsartikel (refereegranskat)abstract
- In beta -decay experiments on C-9 at CERN/ISOLDE the beta -strength was determined to the ground state, the 12.2 MeV excited state and the Isobaric Analog State (IAS) at 14.655 MeV in B-9. A large beta -strength asymmetry is deduced for the mirror transitions of C-9 and Li-9 to states around 12 MeV excitation energy. A satisfactory description of the three-body decay from a narrow energy region around the 12.2 MeV resonance is obtained within a sequential model involving the ground and first-excited states of Li-5 and Be-8. From the study of angular correlations the spin of the 12.2 MeV state is determined as 5/2(-). For the first time the population of the IAS is observed in beta -decay and new information on the decay of this state is obtained. The advantages of a closely packed. highly segmented detector setup are demonstrated. (C) 2001 Elsevier Science B.V. All rights reserved.
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| 5. |
- Borge, M. J. G., et al.
(författare)
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Proton dripline studies at ISOLDE: Ar-31 and C-9
- 2002
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Ingår i: Nuclear Physics A. - 0375-9474. ; 701, s. 373C-377C
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Konferensbidrag (refereegranskat)abstract
- In this contribution examples of the application of new technologies to disentangle the mechanism of beta-delayed multiparticle emission are given. In particular the mechanism of beta-delayed two-proton emission from Ar-31 has been resolved and proved to be sequential, a preview of C-9-decay data is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 6. |
- Aleksandrov, D., et al.
(författare)
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Halo excitations in fragmentation of He-6 at 240 MeV/u on carbon and lead targets
- 2000
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Ingår i: Nuclear Physics A. - 0375-9474. ; 669:1-2, s. 51-64
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Tidskriftsartikel (refereegranskat)abstract
- Dissociation of a 240 MeV/u beam of He-6, incident on carbon and lead targets, has been studied in kinematically complete experiments to investigate low-lying excitation modes in the halo nucleus He-6. It is shown that alignment effects characterize the inelastic scattering and allow an unambiguous assignment of the spin of a narrow resonance observed in the excitation energy spectrum. The differential cross sections for the He-6 inelastic scattering on carbon and lead targets were deduced from the measured moments of the two neutrons and the a-particle. An analysis of these distributions shows that quadrupole and, possibly, monopole excitations characterize the hadronic interaction, while the dipole mode is dominating in Coulomb dissociation. Neither theoretically predicted new resonance states in He-6 nor nuclear excitation of a dipole mode were found. Direct evidence has been obtained for strong suppression of Coulornb post-acceleration in direct Coulomb breakup in a lead target.
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| 7. |
- Markenroth, Karin, 1973, et al.
(författare)
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He-8-He-6: a comparative study of nuclear fragmentation reactions
- 2001
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Ingår i: Nuclear Physics A. - 0375-9474. ; 679:3-4, s. 462-480
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Tidskriftsartikel (refereegranskat)abstract
- Dissociation of 227 MeV/u He-8 in a carbon target has been studied in kinematically complete experiments. The data include the relative energy spectrum, angular distributions in the neutron knock-out channel (He-6 + n) as well as diffractive dissociation and inelastic scattering into the (He-6 + 2n) channel. The data are compared with corresponding results from the well-known halo nucleus He-6. In both cases it is found that neutron knock-out is the: dominating reaction channel. The relative energy spectrum (He-6 + n) shows a structure, which is interpreted as being due to the I-pi = 3/2(-) resonance in the He-7 ground state with about equal contribution from its I-pi = 1/2(-) spin-orbit partner. The He-7 resonance shows a spin alignment similar to that observed in He-5, but with a smaller anisotropy indicating that the structure of the He-8 ground state is more complicated than that of He-6. The data in the (He-6 + 2n) channel were used to identify resonances in the excitation energy spectrum of He-8. If the spectrum is interpreted as two overlapping resonances, the spin-parity assignment for these is found to be 2(+) and 1(-), respectively.
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| 8. |
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