| 1. |
- 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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| 2. |
- 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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| 3. |
- Chulkov, L. V., et al.
(författare)
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Three-body correlations in electromagnetic dissociation of Borromean nuclei: The He-6 case
- 2005
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 759:1-2, s. 23-42
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Tidskriftsartikel (refereegranskat)abstract
- Dissociation of He-6 on a lead target has been studied at 240 MeV/u. The four-momenta of the two neutrons in coincidence with alpha-particles have been measured and used to reconstruct the three-body energy and angular correlations in the final state. For the first time, three-body correlations were included in the analysis of the He-6 dissociation data, and compared with calculations assuming a dipole mode for the electromagnetic dissociation. In addition, the experimental data have been analyzed using a series expansion of the final transition amplitude into hyperspherical functions, showing the importance of both nn and alpha n final-state interactions. It is shown that the dissociation process is governed by a transition of one neutron from the p-shell in the 6He ground state to the s-shell in the continuum further indicating that the role of the transition through an intermediate He-5(3/2(-)) state is more important than expected. (c) 2005 Elsevier B.V. All rights reserved.
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| 4. |
- Cortina-Gil, D., et al.
(författare)
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One-neutron knockout of O-23
- 2005
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 25, s. 343-346
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Konferensbidrag (refereegranskat)abstract
- Breakup reactions were used to study the ground-state configuration of the neutron-rich isotope O-23. The O-22 fragments produced in one-nucleon removal from O-23 at 938 MeV/nucleon in a carbon target were detected in coincidence with de-exciting gamma rays, allowing to discern between 220 ground-state and excited-states contributions. From the comparison of exclusive experimental momentum distributions for the one-neutron removal channel to theoretical momentum distributions calculated in an Eikonal model for the knockout process, and spin and parity assignment of I-pi = 1/2(+) was deduced for the 230 ground state. This result solved the existent experimental discrepancy.
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| 5. |
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| 6. |
- Kanungo, R., et al.
(författare)
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One-Neutron Removal Measurement Reveals O-24 as a New Doubly Magic Nucleus
- 2009
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 102:15
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Tidskriftsartikel (refereegranskat)abstract
- The first measurement of the momentum distribution for one-neutron removal from O-24 at 920A MeV performed at GSI, Darmstadt is reported. The observed distribution has a width (FWHM) of 99 +/- 4 MeV/c in the projectile rest frame and a one-neutron removal cross section of 63 +/- 7 mb. The results are well explained with a nearly pure 2s(1/2) neutron spectroscopic factor of 1.74 +/- 0.19 within the eikonal model. This large s-wave probability shows a spherical shell closure thereby confirming earlier suggestions that O-24 is a new doubly magic nucleus.
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| 7. |
- Maierbeck, P., et al.
(författare)
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Probing the single particle structure around Ca-54 with one-neutron knock-out
- 2008
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Ingår i: AIP Conference Proceedings. - 1551-7616 .- 0094-243X. ; 1012, s. 89-93
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Konferensbidrag (refereegranskat)abstract
- The nuclei Ca-47 and Ti-55 were populated in one-neutron knock-out reactions at relativistic energies. Momentum distributions of the residual nuclei as well as gamma-ray spectra were measured at the GSI fragment separator (FRS). Preliminary results of the ongoing analysis including cross sections and spin/parity assignments are presented.
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| 8. |
- Maierbeck, P., et al.
(författare)
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Structure of 55Ti from relativistic one-neutron knockout
- 2009
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 675:1, s. 22-27
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Tidskriftsartikel (refereegranskat)abstract
- Results are presented from a one-neutron knockout reaction at relativistic energies on 56Ti using the GSI FRS as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive and exclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the orbital angular momentum of the populated states. First-time observation of the 955(6) keV -hole state in 55Ti is reported. The measured data for the first time proves that the ground state of 55Ti is a 1/2- state, in agreement with shell-model calculations using the GXPF1A interaction that predict a sizable N=34 gap in 54Ca.
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| 9. |
- Nociforo, C., et al.
(författare)
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Shell Closure N=16 in O-24
- 2009
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Ingår i: AIP Conference Proceedings. - 1551-7616 .- 0094-243X. ; 1165, s. 90-93 461
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Konferensbidrag (refereegranskat)abstract
- Advanced nuclear structure models predict the presence of the shell closures N=14, 16 in neutron-rich O isotopes rather than N=20. Spectroscopic investigations performed at the neutron drip line have recently confirmed such predictions showing that the O-24 is a doubly magic nucleus (Z=8, N=16). Predictions within the shell model calculation for the O-23,O-24 ground state have been confirmed measuring their spectroscopic factors. Results obtained in one-neutron removal reactions performed by using in-flight radioactive ion beams produced at the Fragment Separator FRS of GSI are reported.
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| 10. |
- Simon, H., et al.
(författare)
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Systematic investigation of the drip-line nuclei 11Li and 14Be and their unbound subsystems 10Li and 13Be
- 2007
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 791:3-4, s. 267-
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Tidskriftsartikel (refereegranskat)abstract
- Fragmentation reactions in a carbon target with beams of 11Li and 14Be at relativistic energies have been studied in a kinematically complete experiment at the ALADIN-LAND setup at GSI. Excited states in 11Li and 14Be were obtained from the data in the inelastic channel. The measured cross sections with the core nucleus in the final state show that in the 14Be case core polarization plays an important role. In the one-neutron knockout channels the measured angular correlations between fragment and neutron are asymmetric, which demonstrates the presence of states with different parities in the 11Li and 14Be ground states. For 10Li a low-lying virtual s-state, a p-state and evidence for a d-state could be extracted from the data, while the 12Be+n system shows resonances with more complicated structure.
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