| 1. |
- Borge, M. J. G., et al.
(författare)
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Asymmetry in the super-allowed beta-transitions of the A=9 isobars
- 2004
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 738:1-4 SUPPL., s. 206-210
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Tidskriftsartikel (refereegranskat)abstract
- We report here on the recent beta-decay studies of the A = 9 isobar made at ISOLDE/CERN. Mirror beta transitions in the A=9 chain are compared and a large asymmetry factor is deduced for the transitions to high excitation energy in Be-9 (11.8 MeV) and B-9 (12.2 MeV) fed in the beta-decay of Li-9 and C-9 respectively. It is shown that the asymmetry is not due to experimental problems or differences in the mechanisms of breakup or in the spin of the states. Only differences in the partial decay branches of the breakup channels have been found. As no asymmetry is found in the gs to gs transition it must be due to the particular structure of these excited states.
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| 2. |
- Borge, M. J. G., et al.
(författare)
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Beta-delayed multiparticle emission studies at ISOL-type facilities
- 2004
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 746, s. 243-243
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Konferensbidrag (refereegranskat)abstract
- We report here on the recent beta-decay studies made at ISOL-type Facilities to determine the multiparticle breakup mechanism of excited states in light nuclei by studying them in full kinematics. In particular the results obtained for the A = 9 isobars and the breakup of the 12.7 MeV state in C-12 of unnatural parity are discussed. The breakup of the latter has been debated since more than a decade. Mirror beta transitions in the A = 9 chain are compared and a large asymmetry factor is deduced for the transitions to high excitation energy in Be-9 (11.8 MeV) and B-9 (12.2 MeV) fed in the beta-decay of Li-9 and C-9 respectively. It is shown that the asymmetry is not due to experimental problems or differences in the mechanisms of breakup or in the spin of the states. As no asymmetry is found in the gs to gs transition it must be due to the particular structure of these excited states. The controversy on the breakup mechanism of the 12.7 MeV state is resolved.
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| 3. |
- Cederkäll, Joakim, et al.
(författare)
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REX-ISOLDE - experiences from the first year of operation
- 2004
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 746, s. 17-17
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Konferensbidrag (refereegranskat)abstract
- The Radioactive beam EXperiment (REX) at CERN-ISOLDE has been commissioned and the first experiments successfully completed during 2002 and 2003. The concept used for post-acceleration has proven to be flexible and the experimental program has therefore been extended during the past year. This paper relays some experiences drawn from using the machine in the current program and also conveys some plans for the future.
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| 4. |
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| 5. |
- Fynbo, H. O. U., et al.
(författare)
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New information on the beta-decay of Li-11 from Doppler broadened gamma lines
- 2004
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 736:1-2, s. 39-54
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Tidskriftsartikel (refereegranskat)abstract
- The gamma-ray spectrum following beta-decay of Li-11 has been remeasured at the ISOLDE facility at CERN. Two new transitions were observed through the use of large Ge-detectors. Most gamma-decays will follow beta-delayed neutron emission. Information on the energy of the neutron is derived from analysis of the gamma line-shape and used to construct a partial decay scheme for Li-11. Lifetime values for the 1(-) and 2(-) levels in Be-10 are also derived. A new partial decay scheme is presented. (C) 2004 Elsevier B.V. All rights reserved.
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| 6. |
- Fynbo, H. O. U., et al.
(författare)
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News on C-12 from beta-decay studies
- 2004
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 738, s. 59-65
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Konferensbidrag (refereegranskat)abstract
- We discuss the importance of the spectroscopic properties of the resonances of C-12 just above the 3alpha-threshold, and review the existing experimental information of this region with emphasis on 0(+) and 2(+) states. A new experimental approach for studying the beta-decays of B-12 and N-12 is presented based on techniques developed in the context of Radioactive beam (rare isotope) physics. Finally preliminary results from an ongoing analysis of two recent experiments are given.
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| 7. |
- Jonson, Björn, 1941
(författare)
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Light dripline nuclei
- 2004
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 734, s. 263-270
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Tidskriftsartikel (refereegranskat)abstract
- Some recent result for light dripline nuclei are reviewed. The main emphasis is put on nulcei with neutron numbers N = 6, 7 and 8.
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| 8. |
- Jonson, Björn, 1941
(författare)
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Light dripline nuclei
- 2004
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573. ; 389:1, s. 1-59
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Tidskriftsartikel (refereegranskat)abstract
- Experimental studies of light dripline nuclei are reviewed. Progress in the production of very short lived nuclei and the development of radioactive nuclear beams has given this field the necessary tools for detailed studies of the most exotic nuclei. A well-known feature for some of the light dripline nuclei is that under certain circumstances they may form a neutron or a proton halo with a dilute mass distribution extending far outside the core of the nucleus. The first observation of halo states was made in the middle of the 1980s and it generated an interest in dripline physics, both experimentally and theoretically, that has gone far beyond the study of halo states. The experimental results for halo states are starting to give a fairly complete understanding of their structure in many cases. The data include masses, spins, moments, reaction data over a wide energy range and beta-decays. There are two main classes of halo state: the two-body halos with one nucleon surrounding the core, like the one-neutron halos Be-11 and C-19 and the one-proton halo B-8; and the Borromean three-body halos with two valence nucleons around the core, the key examples being He-6, Li-11 and Be-14. Experimental information about systems lying just outside the dripline play an important role in understanding the structure of the halo states, examples being Li-10 and Be-13, which form two-body subsystems of Li-11 and Be-14, respectively. Unbound resonance states that correspond to exotic unbound quantum systems like H-5, H-7 and He-9 have been identified. There are continuum states existing above the particle separation threshold as well as spectra indicating cluster or molecular structure. The traditional magic numbers valid for more stable nuclei have been found to disappear and be replaced with new ones in the dripline regions. The beta-decays in these regions may give access to halos in excited states and the associated beta-delayed particle decay modes provide information about coupling to the continuum.After a short historical overview, examples on the most recent experimental results from this rapidly growing field of nuclear physics will be given.
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