Island of Inversion in neutron-rich cobalt isotopes revealed from mass measurements

Abstract

Mass measurements of the ground and isomeric states of ⁶⁸⁻⁷⁰Co have been performed using the JYFLTRAP Penning-trap mass spectrometer at the IGISOL facility. The masses were measured, either for the first time for the isomeric states of ⁶⁸Co and ⁷⁰Co, or with greatly improved precision for the others, removing ambiguities in the mass surface beyond N=40. The ordering of the low and high-spin states in ⁶⁸Co and ⁷⁰Co has also been established. The results, supported by Large-Scale Shell Model and Discrete Non-Orthogonal Shell-Model calculations, show a gradual lowering of intruder states with increasing neutron number, eventually leading to an inversion in ⁷⁰Co. These findings clarify previously proposed contradictory interpretations. Finally, we demonstrate the importance of including induced effective 3N forces for a consistent description of binding energies in the island of inversion near N=40.

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BibTeX

@misc{flayol2026island,
  title = {{Island of Inversion in neutron-rich cobalt isotopes revealed from mass measurements}},
  author = {M Flayol and P Ascher and D.D Dao and M Gerbaux and S Grévy and F Nowacki and A de Roubin and D Atanasov and B Blank and L Canete and Q Délignac and T Eronen and Z Ge and M Hukkanen and A Jaries and A Kankainen and I.D Moore and M Mougeot and A Raggio and J Ruotsalainen and M Stryjczyk and V Virtanen},
  howpublished = {HAL},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.10754},
  eprint = {2609.10754},
  archivePrefix = {arXiv},
  url = {https://hal.science/hal-05759230v1},
}

RIS

TY  - UNPB
TI  - Island of Inversion in neutron-rich cobalt isotopes revealed from mass measurements
AU  - M Flayol
AU  - P Ascher
AU  - D.D Dao
AU  - M Gerbaux
AU  - S Grévy
AU  - F Nowacki
AU  - A de Roubin
AU  - D Atanasov
AU  - B Blank
AU  - L Canete
AU  - Q Délignac
AU  - T Eronen
AU  - Z Ge
AU  - M Hukkanen
AU  - A Jaries
AU  - A Kankainen
AU  - I.D Moore
AU  - M Mougeot
AU  - A Raggio
AU  - J Ruotsalainen
AU  - M Stryjczyk
AU  - V Virtanen
PY  - 2026
DA  - 2026/09/09
PB  - HAL
DO  - 10.48550/arxiv.2609.10754
UR  - https://hal.science/hal-05759230v1
AB  - Mass measurements of the ground and isomeric states of ^68−70Co have been performed using the JYFLTRAP Penning-trap mass spectrometer at the IGISOL facility. The masses were measured, either for the first time for the isomeric states of ^68Co and ^70Co, or with greatly improved precision for the others, removing ambiguities in the mass surface beyond N=40. The ordering of the low and high-spin states in ^68Co and ^70Co has also been established. The results, supported by Large-Scale Shell Model and Discrete Non-Orthogonal Shell-Model calculations, show a gradual lowering of intruder states with increasing neutron number, eventually leading to an inversion in ^70Co. These findings clarify previously proposed contradictory interpretations. Finally, we demonstrate the importance of including induced effective 3N forces for a consistent description of binding energies in the island of inversion near N=40.
ER  -

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