| 11. |
- Rodriguez-Tajes, C., et al.
(author)
-
Gamma-ray measurements in the one-neutron knockout of C-17, N-19, O-21 and F-25
- 2012
-
In: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 48:7, s. Article Number: 95-95
-
Journal article (peer-reviewed)abstract
- One-neutron knockout reactions in a 9 Be target have been investigated at relativistic energies, near 700 MeV/u, for a set of sd-shell, neutron-rich nuclei. The experiment was performed in the FRS spectrometer, at GSI. gamma-ray measurements were carried out by means of the MINIBALL gamma-ray spectrometer and allowed the determination of partial cross-sections and branching ratios corresponding to the final states of the emerging knockout fragments. Experimental results are presented for C-17, N-19, O-21 and F-25 projectiles. The role of excited states of the N - 1 fragments in the composition of the ground state of these neutron-rich projectiles is outlined in this work.
|
|
| 12. |
- Rodriguez-Tajes, C., et al.
(author)
-
One-neutron knockout from light neutron-rich nuclei at relativistic energies
- 2010
-
In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 82:2
-
Journal article (peer-reviewed)abstract
- One-neutron knockout reactions from neutron-rich nuclei, with Z=6-13 and N=8-22, were studied at the Fragment Separator (GSI) at high beam energies, around 700 MeV/nucleon. Structural phenomena such as the formation of one-neutron halos in odd-mass carbon isotopes (15,17,19C) will be discussed. In addition, one-neutron knockout measurements from 22N were carried out for the first time and demonstrate clearly the change from a 0d5/2 to a 1s1/2 orbital for the valence neutron, an effect that is expected above N=14 and that was also observed in 23O and 24F. The possibility of an anomalous structure of 26F, due to a significant 1s1/2 neutron admixture, will also be discussed in the light of the experimental data obtained in this work. Finally, the ground-state configuration of neutron-rich neon isotopes (24-28Ne) was studied, providing new information in a region that is relatively close to the island of inversion.
|
|
| 13. |
- Rodriguez-Tajes, C., et al.
(author)
-
One-neutron knockout from Ne24-28 isotopes
- 2010
-
In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 687:1, s. 26-30
-
Journal article (peer-reviewed)abstract
- One-neutron knockout reactions of Ne24-28 in a beryllium target have been studied in the Fragment Separator (FRS), at GSI. The results include inclusive one-neutron knockout cross-sections as well as longitudinal-momentum distributions of the knockout fragments. The ground-state structure of the neutron-rich neon isotopes was obtained from an analysis of the measured momentum distributions. The results indicate that the two heaviest isotopes, Ne-27 and Ne-28, are dominated by a configuration in which a s(1/2) neutron is coupled to an excited state of the Ne-26 and Ne-27 core, respectively. (C) 2010 Elsevier B.V. All rights reserved.
|
|
| 14. |
- Rodriguez-Tajes, C., et al.
(author)
-
Structure of 22N and the N=14 subshell
- 2011
-
In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 83:6
-
Journal article (peer-reviewed)abstract
- One-neutron knockout data for N18-22 are analyzed in the eikonal approximation of the Glauber model. The role of the s-d shell and the crossing of the N = 14 neutron subshell are discussed. Of particular interest is the nucleus N-22, where the knockout data provide a sensitive experimental test for a possible halo structure of its ground state. The observation of a narrow momentum distribution of the N-21 fragments, together with an essential 1s(1/2) contribution needed to describe the observed longitudinal-momentum distribution, allow the firm conclusion that the ground state of N-22 is a well-developed nuclear halo. The results also show that the N = 14 subshell in N-22 is somewhat reduced as compared to that of O-23.
|
|
| 15. |
- Rossi, D., et al.
(author)
-
Coulomb excitation of exotic nuclei at the R3B-LAND setup
- 2013
-
In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 420:1
-
Conference paper (peer-reviewed)abstract
- Exotic Ni isotopes have been measured at the R3B-LAND setup at GSI in Darmstadt, using Coulomb excitation in inverse kinematics at beam energies around 500 MeV/u. As the experimental setup allows kinematically complete measurements, the excitation energy was reconstructed using the invariant mass method. The GDR and additional low-lying strength have been observed in 68Ni, the latter exhausting 4.1(1.9)% of the E1 energy-weighted sum rule. Also, the branching ratio for the non-statistical decay of the excited 68Ni nuclei was measured and amounts to 24(4)%.
|
|
| 16. |
- Rossi, D. M., et al.
(author)
-
Investigation of the Dipole Response in Exotic Nuclei-Experiments at the LAND-(RB)-B-3 Setup
- 2012
-
In: Progress of Theoretical Physics Supplement. - 1347-4081 .- 0375-9687. ; :196, s. 465-470
-
Journal article (peer-reviewed)abstract
- We present experimental results on the electromagnetic excitation of neutron-rich nickel isotopes, making use of the (RB)-B-3-LAND setup at GSI. Exotic beams were produced at approximately 500 MeV/u and their reactions were studied in inverse kinematics. Integral cross sections for Ni-58 are discussed and compared to previous data, providing a validation of our experimental method. The El excitation-energy distribution of the unstable Ni-68 is presented as well, showing an excess in cross section in the 1n decay channel when compared only with a typical Giant Dipole Resonance.
|
|
| 17. |
- Rossi, D., et al.
(author)
-
Measurement of the dipole polarizability of the unstable neutron-rich nucleus Ni68
- 2013
-
In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 111:24
-
Journal article (peer-reviewed)abstract
- The E1 strength distribution in Ni68 has been investigated using Coulomb excitation in inverse kinematics at the RB3-LAND setup and by measuring the invariant mass in the one- and two-neutron decay channels. The giant dipole resonance and a low-lying peak (pygmy dipole resonance) have been observed at 17.1(2) and 9.55(17) MeV, respectively. The measured dipole polarizability is compared to relativistic random phase approximation calculations yielding a neutron-skin thickness of 0.17(2) fm. A method and analysis applicable to neutron-rich nuclei has been developed, allowing for a precise determination of neutron skins in nuclei as a function of neutron excess.
|
|
| 18. |
- Schwertel, S., et al.
(author)
-
One-neutron knockout from Sc51-55
- 2012
-
In: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 48:Dec., s. 191-10
-
Journal article (peer-reviewed)abstract
- Results are presented from a one-neutron knockout experiment at relativistic energies of approximate to 420 A MeV on Sc51-55 using the GSI Fragment Separator as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the contributions corresponding to knockout from the nu p(1/2), nu p(3/2), (L = 1) and nu f(7/2), nu f(5/2) (L = 3) neutron orbitals. The observed L = 1 and L = 3 contributions are compared with theoretical cross-sections using eikonal knockout theory and spectroscopic factors from shell model calculations using the GXPF1A interaction. The measured inclusive knockout cross-sections generally follow the trends expected theoretically and given by the spectroscopic strength predicted from the shell model calculations. However, the deduced L = 1 cross-sections are generally 30-40% higher while the L = 3 contributions are about a factor of two smaller than predicted. This points to a promotion of neutrons from the nu f(7/2) to the nu p(3/2) orbital indicating a weakening of the N = 28 shell gap in these nuclei. While this is not predicted for the phenomenological GXPF1A interaction such a weakening is predicted by recent calculations using realistic low-momentum interactions V-lowk obtained by evolving a chiral N3LO nucleon-nucleon potential.
|
|
| 19. |
- Uberseder, E., et al.
(author)
-
First Experimental Constraint on the Fe-59(n, gamma)Fe-60 Reaction Cross Section at Astrophysical Energies via the Coulomb Dissociation of Fe-60
- 2014
-
In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 112:21
-
Journal article (peer-reviewed)abstract
- The radionuclide Fe-60 has been of great interest to the nuclear astrophysics community for over a decade. An initial discrepancy between the observed and modeled Galactic Fe-60/Al-26 ratio motivated numerous studies focused on the nucleosynthesis of these two isotopes, though the cross section of the primary astrophysical production reaction, Fe-59(n,gamma)Fe-60, has remained purely theoretical. The present work offers a first experimental constraint on the Fe-59(n,gamma)Fe-60 cross section at astrophysical energies, obtained indirectly via Coulomb dissociation, and demonstrates that the theoretical reaction rates used in present stellar models are not highly erroneous.
|
|
| 20. |
- Wamers, F., et al.
(author)
-
Exclusive measurements of nuclear breakup reactions of 17Ne
- 2014
-
In: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 66
-
Conference paper (peer-reviewed)abstract
- We have studied one-proton-removal reactions of about 500MeV/u 17Ne beams on a carbon target at the R3B/LAND setup at GSI by detecting beam-like 15O-p and determining their relative-energy distribution. We exclusively selected the removal of a 17Ne halo proton, and the Glauber-model analysis of the 16F momentum distribution resulted in an s2 contribution in the 17Ne ground state of about 40%. © Owned by the authors, published by EDP Sciences, 2014.
|
|
