Quasi shell gap at 23F
Abstract
The experimental states of nuclei, close to semi-magic nuclei, having one extra proton on top of closed proton core, in general, connote the arrangement of proton orbitals within a shell. Herein, we have studied the arrangement of proton orbitals (π 0d5/2, π 1s1/2 and π 0d3/2) in sd-shell for Fluorine isotopes within the nuclear shell model framework. The contribution of different components of effective nucleon-nucleon interaction in the evolution of the energies of proton orbitals, and the orbital energy gaps π 0d5/2 - π 1s1/2 and π 0d5/2 - π 0d3/2 at 23,25F has been examined. Results show the evolution of quasi-shell gap at 23F due to key contribution of central force, in particular, of its even-channel, and destructive interference in the contribution of spin-orbit and tensor force. The excitation energies of 1/21+ and 3/21+ states of 23F, and 1/21+ state of 25F are in good agreement with their respective orbital energy gaps. The origin of 3/21+ state of 25F and its excitation energy has been delineated as an effect of the breakdown of semi-magic core 24O.
- Publication:
-
Nuclear Physics A
- Pub Date:
- March 2019
- DOI:
- 10.1016/j.nuclphysa.2018.11.022
- Bibcode:
- 2019NuPhA.983..210K
- Keywords:
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- Effective single particle energy;
- Orbital energy gap;
- Shell model;
- Single particle nature