| 1. |
- Aleksandrov, D., et al.
(författare)
-
Halo excitations in fragmentation of He-6 at 240 MeV/u on carbon and lead targets
- 2000
-
Ingår i: Nuclear Physics A. - 0375-9474. ; 669:1-2, s. 51-64
-
Tidskriftsartikel (refereegranskat)abstract
- Dissociation of a 240 MeV/u beam of He-6, incident on carbon and lead targets, has been studied in kinematically complete experiments to investigate low-lying excitation modes in the halo nucleus He-6. It is shown that alignment effects characterize the inelastic scattering and allow an unambiguous assignment of the spin of a narrow resonance observed in the excitation energy spectrum. The differential cross sections for the He-6 inelastic scattering on carbon and lead targets were deduced from the measured moments of the two neutrons and the a-particle. An analysis of these distributions shows that quadrupole and, possibly, monopole excitations characterize the hadronic interaction, while the dipole mode is dominating in Coulomb dissociation. Neither theoretically predicted new resonance states in He-6 nor nuclear excitation of a dipole mode were found. Direct evidence has been obtained for strong suppression of Coulornb post-acceleration in direct Coulomb breakup in a lead target.
|
|
| 2. |
- Chulkov, L. V., et al.
(författare)
-
Three-body correlations in electromagnetic dissociation of Borromean nuclei: The He-6 case
- 2005
-
Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 759:1-2, s. 23-42
-
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.
|
|
| 3. |
- Markenroth, Karin, 1973, et al.
(författare)
-
He-8-He-6: a comparative study of nuclear fragmentation reactions
- 2001
-
Ingår i: Nuclear Physics A. - 0375-9474. ; 679:3-4, s. 462-480
-
Tidskriftsartikel (refereegranskat)abstract
- Dissociation of 227 MeV/u He-8 in a carbon target has been studied in kinematically complete experiments. The data include the relative energy spectrum, angular distributions in the neutron knock-out channel (He-6 + n) as well as diffractive dissociation and inelastic scattering into the (He-6 + 2n) channel. The data are compared with corresponding results from the well-known halo nucleus He-6. In both cases it is found that neutron knock-out is the: dominating reaction channel. The relative energy spectrum (He-6 + n) shows a structure, which is interpreted as being due to the I-pi = 3/2(-) resonance in the He-7 ground state with about equal contribution from its I-pi = 1/2(-) spin-orbit partner. The He-7 resonance shows a spin alignment similar to that observed in He-5, but with a smaller anisotropy indicating that the structure of the He-8 ground state is more complicated than that of He-6. The data in the (He-6 + 2n) channel were used to identify resonances in the excitation energy spectrum of He-8. If the spectrum is interpreted as two overlapping resonances, the spin-parity assignment for these is found to be 2(+) and 1(-), respectively.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Cortina-Gil, D., et al.
(författare)
-
One-neutron knockout of O-23
- 2005
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 25, s. 343-346
-
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.
|
|
| 7. |
|
|
| 8. |
- Meister, Mikael, 1969, et al.
(författare)
-
High-energy breakup of 8B
- 2003
-
Ingår i: Nucl. Phys. A. ; 718, s. 431-433
-
Konferensbidrag (refereegranskat)
|
|
| 9. |
|
|
