| 1. |
- Ovejas, J. D., et al.
(författare)
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Halo effects in the low-energy scattering of 15 C with heavy targets
- 2020
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Ingår i: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 51:3, s. 731-736
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Tidskriftsartikel (refereegranskat)abstract
- The neutron-rich carbon isotope 15C was postulated to be a halo nucleus (Sn = 1215 keV, S2n = 9395 keV) according to different high-energy experiments. If so, it would be the only halo nucleus exhibiting a "pure" s-wave structure of the ground state. At low collision energies, the effect of this halo structure should manifest as a strong absorption pattern in the angular distribution of the elastic cross section, with a total suppression of the nuclear rainbow due to the large neutron transfer and breakup probabilities, enhanced by the halo configuration. The IS619 experiment, carried out at the HIE-ISOLDE facility at CERN (Switzerland), is the first dynamical study of this nucleus at energies around the Coulomb barrier. It aims to probe the halo structure via the measurement of the elastic cross section on a high-Z 208Pb target. Preliminary results of the elastic cross section are discussed and compared to Optical Model calculations.
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| 2. |
- Ovejas, J. D., et al.
(författare)
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Study of the scattering of 15C at energies around the Coulomb barrier
- 2020
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 1643:1
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Konferensbidrag (refereegranskat)abstract
- The neutron rich carbon isotope 15C is the only known case of an almost "pure"2s1/2 single-neutron halo ground state configuration. At collision energies around the Coulomb barrier the reaction dynamics is expected to be dominated by single neutron transfer and breakup. To investigate these effects, we have measured the scattering of 15C with a 208Pb target at 65 MeV at the HIE-ISOLDE facility in CERN (Geneva, Switzerland). The preliminary data demonstrates the presence of a strong long-range absorption pattern in the angular distribution of the elastic cross section. The results are discussed in the framework of Optical Model calculations.
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| 3. |
- Távora, V.G., et al.
(författare)
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Strong coupling effects on near-barrier 15C + 208Pb elastic scattering
- 2024
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Ingår i: Physics Letters B. - 0370-2693. ; 855
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Tidskriftsartikel (refereegranskat)abstract
- The presence of a neutron halo in 15C has been demonstrated in several reaction experiments at intermediate energies. In the present study, the dynamical effects of this structure are observed for the first time at Coulomb barrier energies in the 15C + 208Pb quasi-elastic scattering at MeV, measured at the HIE-ISOLDE facility, CERN using the high-granularity detector array GLORIA. A combined continuum discretised coupled channels and coupled reaction channels calculation describes the data well and significant coupling effects due both to breakup and single-neutron stripping are identified.
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| 4. |
- Delafosse, C., et al.
(författare)
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Pseudospin Symmetry and Microscopic Origin of Shape Coexistence in the Ni-78 Region : A Hint from Lifetime Measurements
- 2018
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 121:19
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Tidskriftsartikel (refereegranskat)abstract
- Lifetime measurements of excited states of the light N = 52 isotones Kr-88, Se-86, and Ge-84 have been performed, using the recoil distance Doppler shift method and VAMOS and AGATA spectrometers for particle identification and gamma spectroscopy, respectively. The reduced electric quadrupole transition probabilities B(E2; 2(+)-> 0(+)) and B(E2; 4(+)-> 2(+)) were obtained for the first time for the hard-to-reach 84Ge. While the B(E2; 2(+)-> 0(+) ) values of Kr-88, Se-86 saturate the maximum quadrupole collectivity offered by the natural valence (3s, 2d, 1g(7/2), 1h(11/2)) space of an inert Ni-78 core, the value obtained for Ge-84 largely exceeds it, suggesting that shape coexistence phenomena, previously reported at N less than or similar to 49, extend beyond N = 50. The onset of collectivity at Z = 32 is understood as due to a pseudo-SU(3) organization of the proton single-particle sequence reflecting a clear manifestation of pseudospin symmetry. It is realized that the latter provides actually reliable guidance for understanding the observed proton and neutron single particle structure in the whole medium-mass region, from Ni to Sn, pointing towards the important role of the isovector-vector rho field in shell-structure evolution.
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