| 1. |
- Doornenbal, P., et al.
(författare)
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RISING: Gamma‐ray Spectroscopy with Radioactive Beams at GSI
- 2007
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X. - 9780735413283 ; 891, s. 99-107
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Konferensbidrag (refereegranskat)abstract
- The Rare Isotope Spectroscopic INvestigation at GSI (RISING) project is a major pan‐European collaboration. Its physics aims are the studies of exotic nuclear matter with abnormal proton‐to‐neutron ratios compared with naturally occurring isotopes. RISING combines the FRagment Separator (FRS) which allows relativistic energies and projectile fragmentation reactions with EUROBALL Ge Cluster detectors for γ spectroscopic research. The RISING setup can be used in two different configurations. Either the nuclei of interest are investigated after being stopped or the heavy ions hit a secondary target at relativistic energies and the thereby occurring excitations are studied. For the latter case, MINIBALL Ge detectors and the HECTOR array are used in addition. Example achievements of the Fast Beam setup are presented and compared to various shell model calculations, while for the Stopped Beam setup initial results are shown.
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| 2. |
- Naqvi, F., et al.
(författare)
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Isomer spectroscopy of (127)Cd
- 2010
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 82:3, s. 034323-
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Tidskriftsartikel (refereegranskat)abstract
- The spin and configurational structure of excited states of (127)Cd, the two-proton and three-neutron hole neighbor of (132)Sn, has been studied. An isomeric state with a half-life of 17.5(3) mu s was populated in the fragmentation of a (136)Xe beam on a (9)Be target at a beam energy of 750 MeV/u. Time distributions of the delayed gamma transitions and gamma gamma coincidence relations were exploited to construct a decay scheme. The observed yrast (19/2)(+) isomer is proposed to have dominant configurations of nu(h(11/2)(-3))pi(g(9/2)(-1), p(1/2)(-1)), nu(h(11/2)(-2)d(3/2)(-1))pi(g(9/2)(-2)), and nu(h(11/2)(-2), s(1/2)(-1))pi(g(9/2)(-2)) and to decay by two competing stretched M2 and E3 transitions. Experimental results are compared with the isotone (129)Sn. The new information provides input for the proton-neutron interaction and the evolution of neutron hole energies in nuclei around the doubly magic (132)Sn core.
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| 3. |
- Caceres, L. S., et al.
(författare)
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Identification of Excited States in the N = Z Nucleus 82Nb
- 2007
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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. ; 38:4, s. 1271-1275
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Tidskriftsartikel (refereegranskat)abstract
- Information on the first excited states in the N = Z = 41 nucleus Nb-82 sheds light on the competition of isospin T = 0 and T = 1 states in the A similar to 80 region. The measurement was performed at the GSI laboratory using fragmentation of a Ag-107 primary beam at 750 MeV/u on a 4 g/cm(2) Be-9 target. The fragments were separated and identified unambiguously in the FRagment Separator. Three excited states were observed and the half-life estimate for the isomeric state was extracted. A tentative spin assignment based on the isobaric analogue states systematics in the T-z = 1 nucleus Zr-82, and transition probabilities indicate T = 1 character of the first two excited states, and T = 0 for the isomeric state.
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| 4. |
- Caceres, L., et al.
(författare)
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Spherical proton-neutron structure of isomeric states in Cd-128
- 2009
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:1, s. 011301-
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Tidskriftsartikel (refereegranskat)abstract
- The gamma-ray decay of isomeric states in the even-even nucleus Cd-128 has been observed. The nucleus of interest was produced both by the fragmentation of Xe-136 and the fission of U-238 primary beams. The level scheme was unambiguously constructed based on.. coincidence relations in conjunction with detailed lifetime analysis employed for the first time on this nucleus. Large-scale shell-model calculations, without consideration of excitations across the N = 82 shell closure, were performed and provide a consistent description of the experimental level scheme. The structure of the isomeric states and their decays exhibit coexistence of proton, neutron, and strongly mixed configurations due to p. interaction in overlapping orbitals for both proton and neutron holes.
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| 5. |
- Garnsworthy, A. B., et al.
(författare)
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Isomeric States in Neutron-deficient A~80-90 Nuclei Populated in the Fragmentation of 107Ag
- 2009
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:6
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Tidskriftsartikel (refereegranskat)abstract
- The relativistic projectile fragmentation of a 750 MeV per nucleon beam of Ag-107 was used to populate isomeric states in neutron-deficient nuclei around A=80-90. Reaction products were separated and unambiguously identified using the GSI FRagment Separator (FRS) and its ancillary detectors. At the final focal plane, the fragments were slowed from relativistic energies by means of an aluminium degrader and implanted in a passive stopper in the center of the high-efficiency, high-granularity Stopped Rare Isotope Spectroscopic INvestigation at GSI (RISING) germanium array. This allowed the identification of excited states in the N=Z nuclei Tc-86(43) and, for the first time, Nb-82(41). Isomeric states have also been identified for the first time in Tc-87,Tc-88, and a previously unreported isomer was observed in Nb-84. Experimental results are presented along with a discussion on the structure of these nuclei based on interpretations provided by several theoretical models.
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| 6. |
- Garnsworthy, A. B., et al.
(författare)
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Isomeric States in the Light Tc Isotopes
- 2007
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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. ; 38:4, s. 1265-1269
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Tidskriftsartikel (refereegranskat)abstract
- Preliminary results from the first experiment of the Stopped Beam RISING campaign are presented. The relativistic projectile fragmentation of a 750 MeV/u beam of Ag-107 populated isomeric states in very neutron deficient nuclei at the proton dripline around mass 80-90. Nuclei were unambiguously identified using the FRagment Separator (FRS) and its ancillary detectors located at GSI. The ions produced were slowed down from relativistic energies by means of an Al degrader and implanted in the centre of the high-efficiency Stopped RISING array. This allowed the identification of new excited states in the N = Z = 43 nucleus, Tc-86, populated following the de-excitation of a microsecond isomer. Preliminary results of this analysis, as well as previously unobserved isomeric states in Tc-87,Tc-88. are reported.
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| 7. |
- Garnsworthy, A B, et al.
(författare)
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Neutron-proton pairing competition in N = Z nuclei: Metastable state decays in the proton dripline nuclei Nb-82(41) and Tc-86(43)
- 2008
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 660:4, s. 326-330
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Tidskriftsartikel (refereegranskat)abstract
- The low-lying structures of the self-conjugate (N = Z) nuclei Nb-82(41)41 and Tc-86(43)43 have been investigated using isomeric-decay spectroscopy following the projectile fragmentation of a Ag-107 beam. These represent the heaviest odd-odd N = Z nuclei in which internal decays have been identified to date. The resulting level schemes shed light on the shape evolution along the N = Z line between the doubly-magic systems Ni-56(28) and Sn-100(50) and support a preference for T = 1 states in T-z = 0 odd-odd nuclei at low excitation energies associated with a T = 1 neutron-proton pairing gap. Comparison with Projected Shell Model calculations suggests that the decay in Nb-82 may be interpreted as an isospin-changing K isomer.
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| 8. |
- Gorska, M., et al.
(författare)
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Nuclear Structure far off Stability - RISING Campaigns
- 2007
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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. ; 38:4, s. 1219-1228
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear structure studies at CST attracted recently increased interest for the results of present activities as well as for the future project FAIR. A broad range of physics phenomena can be addressed by high-resolution in-beam gamma-ray spectroscopy experiments with radioactive beams offered within the Rare Isotopes Spectroscopic INvestigation at GSI (RISING) project. It combined the EUROBALL Ge-Cluster detectors, the MINIBALL Ce detectors, the HECTOR-BaF detectors, and the fragment separator FRS. The secondary beams produced at relativistic energies were used for Coulomb excitation or secondary fragmentation experiments to study projectile like nuclei by measuring de-excitation photons. The first results of the "fast beam campaign" is discussed in comparison to various shell model calculations. The discussion focuses on the N = 32, 34 sub-shell closure based on neutron rich Cr isotopes. Alternatively, the relativistic radioactive beams, both in their ground and isomeric states, were implanted and their decay could be investigated. The "stopped beam campaign" has started in October 2005 with a series of g-factor measurements. It continued from February 2006 with the next, configuration and the main goal of identification of new isomers and angular momentum population in fragmentation reactions.
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| 9. |
- Lozeva, R. L., et al.
(författare)
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New sub-us Isomers in 125Sn, 127Sn, 129Sn and Isomer Systematics of 124-130Sn
- 2008
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 77:6
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Tidskriftsartikel (refereegranskat)abstract
- New sub-mu s isomers have been observed in the neutron-rich Sn isotopes. Sn-125,Sn-127,Sn-129 nuclei have been produced in a relativistic fission reaction of U-238 on a Be-9 target at 750 A.MeV and by the fragmentation of Xe-136 at 600 A.MeV populating high-spin yrast states. In addition to the already known mu s isomers, three new ones with sub-mu s half-lives have been observed. These yrast isomers are the high-spin members of the nu(d(3/2)(-1)h(11/2)(-2)) and nu h(11/2)(-n), seniority v = 3 multiplets leading to isomeric (23/2(+)) and (27/2(-)) states, respectively. Added to the already known 19/2(+)mu s isomers in this region the current work completes the systematic information of neutron-hole excitations toward the filling of the last h(11/2) orbital at N = 82. The results are discussed in the framework of state-of-the-art shell-model calculations using realistic interactions.
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| 10. |
- Myalski, S., et al.
(författare)
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Isomeric Ratio for the I=8+ Yrast State in 96Pd Produced in the Relativistic Fragmentation of 107Ag
- 2007
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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. ; 38:4, s. 1277-1282
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Tidskriftsartikel (refereegranskat)abstract
- We report on the preliminary results from a study of the decay of the I-pi = 8(+) T-1/2 = 2 mu s isomer in Pd-96 performed as part of the Stopped-Beam RISING campaign within the Rare Isotope Investigation at GSI (RISING). The Pd-96 ions were produced following the projectile fragmentation of a 750 MeV per nucleon Ag-107 primary beam. The reaction products were separated and identified by the in-flight method using the GSI Fragment Separator. The residues of interest were stopped in a perspex stopper surrounded by an array of 15, seven-element germanium Cluster detectors. One of the goals of the current work is to investigate the population of high-spin states produced projectile fragmentation reactions using isomeric ratio measurements to infer information on the angular momentum population distribution. In this short contribution the method and results of determining the isomeric ratio for the I-pi = 8(+) microsecond isomer in Pd-96 nucleus are presented.
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