| 1. |
- Neyens, G., et al.
(författare)
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g-Factor Measurements on Relativistic Isomeric Beams Produced by Fragmentation and U-fission: The g-RISING Project at GSI
- 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. 1237-1247
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Tidskriftsartikel (refereegranskat)abstract
- Within the RISING (Rare ISotope INvestigations @ GSI) Collaboration at GSI, g factor measurements have been performed on isomeric states in neutron-rich isotopes approaching Sn-132 and in the neutron deficient Pb-region (the g-RISING campaign). We present the experimental technique and some typical aspects related to such studies on relativistic beams selected with the FRS fragment separator. First results are presented for the (19/2(+)) 4.5 mu s isomeric state in Sn-127, which has been produced by means of fission of a relativistic U-238 beam on the one hand, and by the fragmentation of a relativistic Xe-136 beam on the other hand. Spin-alignment has been observed in both reactions. It was the first time that spin-alignment has been established in a relativistic fission reaction.
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| 2. |
- Atanasova, L., et al.
(författare)
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g-factor Measurements at RISING: The Cases of 127Sn and 128Sn
- 2010
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Ingår i: Europhysics Letters. - : IOP Publishing. - 0295-5075. ; 91:4
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Tidskriftsartikel (refereegranskat)abstract
- We report on g-factor measurements of the 19/2(+) T-1/2 = 4.5(3) mu s isomer in Sn-127 and the 10(+) T-1/2 = 2.69(23) mu s isomer in Sn-128. These isomers were produced and spin-aligned in relativistic heavy-ion fragmentation at GSI and were selected and separated by the GSI fragment separator ( FRS). The gamma-rays of the isomeric decay were detected by the RISING gamma-ray spectrometer. The method of time-differential perturbed angular distributions was utilized. The measured g-factors, g(19/2(+); Sn-127) =-0.17(2) and g(10(+); Sn-128)=-0.20(4), are compared with shell model calculations. The measured g-factors confirm the predominantly nu h(11/2)(-2) and nu(s(1/2)(-1) h(11/2)(-2)) character of the 10(+) and 19/2(-) isomers in Sn-128 and Sn-127, respectively. The results demonstrate the feasibility of the method for similar measurements in exotic neutron-rich nuclei. Copyright (C) EPLA, 2010
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| 3. |
- Gorska, M., et al.
(författare)
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Evolution of the N=82 Shell Gap below 132Sn Inferred from Core Excited States in 131In
- 2009
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 672:4-5, s. 313-316
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Tidskriftsartikel (refereegranskat)abstract
- The gamma-ray decay of ail excited state in In-131, the one proton hole neighbor of the doubly magic (132)sn has been measured. A high-spin, core-excited isomer with T-1/2 = 630(60) us was identified following production by both relativistic fragmentation of a Xe-136 beam and fission Of a U-238 beam. This state deexcites by a single gamma-ray branch of 3782(2) keV from which direct evidence for the size of the N = 82 shell gal) is inferred. The results are discussed in comparison to a shell-model Calculation including configurations across the closed shells at N = 82 and Z = 50. (C) 2009 Elsevier B.V. All rights reserved.
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| 4. |
- 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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| 5. |
- Kmiecik, M., et al.
(författare)
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Spin-alignment and g-factor Measurement of the I=12+ Isomer in 192Pb Produced in the Relativistic-energy Fragmentation of a 238U Beam
- 2010
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 45:2, s. 153-158
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Tidskriftsartikel (refereegranskat)abstract
- The feasibility of measuring g-factors using the TDPAD method applied to high-energy, heavy fragmentation products is explored. The 2623 keV I-pi = 12(+) isomer in Pb-192 with tau = 1.57 mu s has been produced using the fragmentation of a 1 A GeV U-238 beam. The results presented demonstrate for the first time that such heavy nuclei produced in a fragmentation reaction with a relativistic beam are sufficiently well spin-aligned. Moreover, the rather large value of the alignment, 28(10)% of the maximum possible, is preserved during the separation process allowing the determination of magnetic moments. The measured values of the lifetime, tau = 1.54(9) mu s, and the g-factor, g = -0.175(20), agree with the results of previous investigations using fusion-evaporation reactions.
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| 6. |
- Wadsworth, R., et al.
(författare)
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Spin-gap Isomer in 96Cd
- 2012
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 381:1
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Tidskriftsartikel (refereegranskat)abstract
- Evidence has been obtained for the existence of the long predicted 16+ spin-gap isomer in 96Cd. The decay of the isomer was identified and studied following the use of an 850 MeV/u beam of 124Xe impinging on a Be target and the fragment recoil separator at the GSI Laboratory. Gamma decays from the fragments were detected using the RISING gamma ray array, in its stopped beam configuration, plus a silicon active stopper. The data obtained have been compared with shell model predictions, which indicate that the isoscalar neutron-proton interaction plays a key role in the formation of the isomer.
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| 7. |
- 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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| 8. |
- Lalkovski, S., et al.
(författare)
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Core-coupled states and split proton-neutron quasiparticle multiplets in Ag122-126
- 2013
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 87:3, s. 034308-
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Tidskriftsartikel (refereegranskat)abstract
- Neutron-rich silver isotopes were populated in the fragmentation of a Xe-136 beam and the relativistic fission of U-238. The fragments were mass analyzed with the GSI Fragment Separator and subsequently implanted into a passive stopper. Isomeric transitions were detected by 105 high-purity germanium detectors. Eight isomeric states were observed in Ag122-126 nuclei. The level schemes of Ag-122,Ag-123,Ag-125 were revised and extended with isomeric transitions being observed for the first time. The excited states in the odd-mass silver isotopes are interpreted as core-coupled states. The isomeric states in the even-mass silver isotopes are discussed in the framework of the proton-neutron split multiplets. The results of shell-model calculations, performed for the most neutron-rich silver nuclei are compared to the experimental data.
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| 9. |
- Pietri, S., et al.
(författare)
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First observation of the decay of a 15(-) seniority v=4 isomer in Sn-128
- 2011
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 83:4, s. 044328-
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Tidskriftsartikel (refereegranskat)abstract
- Isomeric states in the semimagic Sn128-130 isotopes were populated in the fragmentation of a Xe-136 beam on a Be-9 target at an energy of 750 A.MeV. The decay of an isomeric state in Sn-128 at an excitation energy of 4098 keV has been observed. Its half live has been determined to be T-1/2 = 220(30) ns from the time distributions of the delayed gamma rays emitted in its decay. gamma gamma coincidence relations were analyzed in order to establish the decay pattern of the newly established state toward the known (7(-)) and (10(+)) isomers at excitation energies of 2092 and 2492 keV, respectively. Based on a comparison with results of state-of-the-art shell-model calculations the new isomeric state is proposed to have the nu h(11/2)(-3)d(3/2)(-1) configuration with the four neutron holes in Sn-132 maximally aligned to a total spin of I-pi = 15(-).
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