| 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. |
- Wollersheim, HJ, et al.
(författare)
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Rare ISotopes INvestigation at GSI (RISING) Using Gamma-ray Spectroscopy at Relativistic Energies
- 2005
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 537:3, s. 637-657
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Tidskriftsartikel (refereegranskat)abstract
- The Rare ISotopes INvestigation at GSI project combines the former EUROBALL Ge-Cluster detectors, the MINIBALL Ge detectors, BaF2--HECTOR detectors, and the fragment separator at GSI for high-resolution in-beam gamma-ray spectroscopy measurements with radioactive beams. These secondary beams produced at relativistic energies are used for Coulomb excitation or secondary fragmentation experiments in order to explore the nuclear structure of the projectiles or projectile like nuclei by measuring de-excitation photons. The newly designed detector array is described and the performance characteristics are given. Moreover, particularities of the experimental technique are discussed.
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| 3. |
- Aksyutina, Yu, et al.
(författare)
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Lithium isotopes beyond the drip line
- 2008
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 666:5, s. 430-434
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Tidskriftsartikel (refereegranskat)abstract
- The unbound isotopes 10Li, 12Li and 13Li have been observed after nucleon-knockout reactions at relativistic energies with 11Li and 14Be beams impinging on a liquid hydrogen target. The channels , and were analysed in the ALADIN-LAND setup at GSI. The 10Li data confirm earlier findings, while the 12Li and 13Li nuclei were observed for the first time. The relative-energy spectrum shows that the ground state of 12Li can be described as a virtual s-state with a scattering length of -13.7(1.6) fm. A broad energy spectrum was found for the channel. Based on the assumption that the relative-energy spectrum is dominated by a correlated background presumably stemming from initial correlations in the 14Be ground-state, evidence for a 13Li resonance at 1.47(31) MeV above the threshold with a width around 2 MeV has been found.
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| 4. |
- Aksyutina, Yuliya, 1983, et al.
(författare)
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Properties of the 7He ground state from 8He neutron knockout
- 2009
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 679:3, s. 191-196
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Tidskriftsartikel (refereegranskat)abstract
- The unbound nucleus 7He, produced in neutron-knockout reactions with a 240 MeV/u 8He beam in a liquid-hydrogen target, has been studied in an experiment at the ALADIN-LAND setup at GSI. From an R-matrix analysis the resonance parameters for 7He as well as the spectroscopic factor for the 6He(0+) + n configuration in its ground-state have been obtained. The spectroscopic factor is 0.61 confirming that 7He is not a pure single-particle state. An analysis of 5He data from neutron-knockout reactions of 6He in a carbon target reveals the presence of an s-wave component at low energies in the α+n relative energy spectrum. A possible low-lying exited state in 7He observed in neutron knockout data from 8He in a carbon target and tentatively interpreted as a Iπ=1/2− state, could not be observed in the present experiment. Possible explanations of the shape difference between the 7He resonance obtained in the two knockout reactions are discussed in terms of target-dependence or different reaction mechanisms at relativistic energies.
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| 5. |
- Alkhomashi, N., et al.
(författare)
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beta(-)-delayed spectroscopy of neutron-rich tantalum nuclei: Shape evolution in neutron-rich tungsten isotopes
- 2009
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:6
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Tidskriftsartikel (refereegranskat)abstract
- The low-lying structure of W-188,W-190,W-192 has been studied following beta decays of the neutron-rich mother nuclei Ta-188,Ta-190,Ta-192 produced following the projectile fragmentation of a 1-GeV-per-nucleon Pb-208 primary beam on a natural beryllium target at the GSI Fragment Separator. The beta-decay half-lives of Ta-188, Ta-190, and Ta-192 have been measured, with gamma-ray decays of low-lying states in their respective W daughter nuclei, using heavy-ion beta-gamma correlations and a position-sensitive silicon detector setup. The data provide information on the low-lying excited states in W-188, W-190, and W-192, which highlight a change in nuclear shape at W-190 compared with that of lighter W isotopes. This evolution of ground-state structure along the W isotopic chain is discussed as evidence for a possible proton subshell effect for the A similar to 190 region and is consistent with maximization of the gamma-softness of the nuclear potential around N similar to 116.
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| 6. |
- 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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| 7. |
- 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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| 8. |
- Murari, A., et al.
(författare)
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Measuring the radiation field and radiation hard detectors at JET : Recent developments
- 2008
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 593:3, s. 492-504
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Tidskriftsartikel (refereegranskat)abstract
- Since in ITER the radiation field will be much more demanding than that of present day devices, research programmes at JET are aimed at developing radiation hard diagnostics and related components. Initially, significant efforts are devoted to determining the radiation field of both the plasma and in the immediate environment with better accuracy. New developments in MCNP calculations and dedicated measurements provide useful information about the radiation field in the Torus Hall, even during non-operational periods. The effect of using Beryllium in the near future for JET first wall, is being assessed. New materials for activation samples are under consideration and will be tested to improve the calibration accuracy of JET neutron diagnostics. The long-term goal of this work is to obtain spectrometric information from an appropriate combination of different materials. Several studies are under way to modify the radiation field at the detectors by using LiH or pure water as neutron filters, to alleviate the problem of the background in gamma-ray measurements. A suite of radiation hard detectors for neutrons, magnetic field and charged particles are being developed. Super-heated fluid neutron detectors, used for yield and imaging, are being upgraded, in order to provide a broadband spectrometric capability. Chemical vapour deposited diamond diodes are being qualified as counters and as spectrometers. Prototypes of Hall probes made of InSb have been installed on the machine and have provided some preliminary results. Si-on-insulator detectors are under development for use in neutral particle analysers and are currently being bench-tested. Some attention is being devoted to optical components, fibres and mirrors, and to investigating radiation hard electronics using reconfigurable Field Programmable Gate Arrays.
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| 9. |
- Al-Dahan, N., et al.
(författare)
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Isomeric States In 208Hg And 209Tl Populated In Fragmentation Of 238U
- 2009
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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. ; 40:3, s. 871-874
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Tidskriftsartikel (refereegranskat)abstract
- The nuclear structure of neutron-rich N > 126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A = 1 GeV U-238 beam on a Be target. The preliminary analysis indicates the presence of previously unreported isomeric states in the N = 128 isotones Hg-208 and Tl-209.
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| 10. |
- Al-Dahan, N., et al.
(författare)
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Nuclear Structure "Southeast" of 208Pb: Isomeric states in 208Hg and 209Tl
- 2009
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:6
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Tidskriftsartikel (refereegranskat)abstract
- The nuclear structure of neutron-rich N>126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A=1 GeV U-238 beam. Metastable states in the N=128 isotones Hg-208 and Tl-209 have been identified. Delayed gamma-ray transitions are interpreted as arising from the decay of I-pi=(8(+)) and (17/2(+)) isomers, respectively. The data allow for the so far most comprehensive verification of the shell-model approach in the region determined by magic numbers Z < 82 and N>126.
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