Large quadrupole deformation in 20Ne challenges rotor model and modern theory
| dc.contributor.author | Mehl, Craig Vernon | |
| dc.contributor.author | Orce, José Nicolás | |
| dc.contributor.author | Ngwetsheni, Cebo | |
| dc.date.accessioned | 2025-11-19T12:46:10Z | |
| dc.date.available | 2025-11-19T12:46:10Z | |
| dc.date.issued | 2025 | |
| dc.description.abstract | The spectroscopic quadrupole moment of the first excited state, QS (2+1 ), at 1.634 MeV in 20Ne was determined from sensitive reorientation-effect Coulomb-excitation measurements using a heavy target and safe energies well below the Coulomb barrier. Particle-γ coincidence measurements were collected at iThemba LABS with a digital data-acquisition system using the AFRODITE array coupled to an annular, doubled-sided silicon detector. A precise value of QS (2+1 ) = −0.22(2) eb was determined at backward angles in agreement with the only safe energy measurement prior to this work, QS (2+1 ) = −0.23(8) eb. This result adopts 1 ¯hω shell-model calculations of the nuclear dipole polarizability of the 2+1 state that contributes to the effective quadrupole interaction and determination of QS (2+1 ). It disagrees, however, with the ideal rotor model for axially symmetric nuclei by almost 3σ. Larger discrepancies are computed by modern state-of-the-art calculations performed in this and prior work, including ab initio shell model with chiral effective interactions and the multireference relativistic energy density functional (MR-EDF) model. The intrinsic nucleon density of the 2+1 state in 20Ne calculated with the MR-EDF model illustrates the presence of α clustering, which explains the largest discrepancy with the rotor model found in the nuclear chart and motivates the explicit inclusion of α clustering for full convergence of E2 collective properties. | |
| dc.identifier.citation | Mehl, C.V., Orce, J.N., Ngwetsheni, C., Marević, P., Brown, B.A., Holt, J.D., Raju, M.K., Lawrie, E.A., Abrahams, K.J., Adsley, P. and Akakpo, E.H., 2024. Large quadrupole deformation in $^{20} $ Ne challenges rotor model and modern theory: urging for $\alpha $ clusters in nuclei. arXiv preprint arXiv:2411.10598. | |
| dc.identifier.uri | https://doi.org/10.1103/PhysRevC.111.054318 | |
| dc.identifier.uri | https://hdl.handle.net/10566/21419 | |
| dc.language.iso | en | |
| dc.publisher | American Physical Society | |
| dc.subject | IThemba labs | |
| dc.subject | Spectroscopic quadrupole | |
| dc.subject | Rotor model | |
| dc.subject | Light ions | |
| dc.subject | Modern theory | |
| dc.title | Large quadrupole deformation in 20Ne challenges rotor model and modern theory | |
| dc.type | Article |