Prominent Bump in the Two-Neutron Separation Energies of Neutron-Rich Lanthanum Isotopes Revealed by High-Precision Mass Spectrometry
We report on high-precision atomic mass measurements of ^{148-153}La and ^{151}Ce performed with the JYFLTRAP double Penning trap using the phase-imaging ion-cyclotron-resonance technique. The masses of ^{152,153}La were experimentally determined for the first time. We confirm the sharp kink in the two-neutron separation energies at the neutron number N=93 in the cerium (Z=58) isotopic chain. Our precision mass measurements of the most exotic neutron-rich lanthanum (Z=57) isotopes reveal a unexpected sudden increase in two-neutron separation energies from N=92 to N=93. Unlike in the cerium isotopic chain, the kink is not sharp but extends to N=94 forming a prominent bump. The gain in energy is about 0.4 MeV, making it one of the strongest changes in two-neutron separation energies over the whole chart of nuclides, away from nuclear shell closures. The results, correlated with a predicted onset of quadrupole deformation for N≥92, call for further studies to elucidate the structure of neutron-rich lanthanum isotopes.
Authors
- Z. W. Ge (ORCID: https://orcid.org/0000-0001-8586-6134)
- M. Hukkanen (ORCID: https://orcid.org/0000-0002-4317-3628)
- A. Raggio (ORCID: https://orcid.org/0000-0002-5365-1494)
- V. Virtanen (ORCID: https://orcid.org/0000-0003-0276-6483)
- M. Mougeot (ORCID: https://orcid.org/0000-0003-1372-1205)
- A. Kankainen (ORCID: https://orcid.org/0000-0003-1082-7602)
- M. Reponen (ORCID: https://orcid.org/0000-0003-1298-7431)
- T. Eronen (ORCID: https://orcid.org/0000-0003-0003-6022)
- S. Nikas (ORCID: https://orcid.org/0000-0003-4282-1299)
- A. Jaries (ORCID: https://orcid.org/0000-0002-5279-0820)
- J. Ruotsalainen (ORCID: https://orcid.org/0000-0002-5589-2005)
- T. Dickel (ORCID: https://orcid.org/0000-0002-5965-8689)
- M. Stryjczyk (ORCID: https://orcid.org/0000-0001-6515-2409)
- O. Beliuskina (ORCID: https://orcid.org/0000-0003-4448-7650)
- M. Flayol
- I. Pohjalainen (ORCID: https://orcid.org/0000-0003-4047-8757)
Institutions
- Université de Bordeaux (FR)
- GSI Helmholtz Centre for Heavy Ion Research (DE)
- Justus-Liebig-Universität Gießen (DE)
- Helsinki Institute of Physics (FI)
- Laboratoire de Physique des deux infinis Bordeaux (FR)
- Centre Émile Durkheim (FR)
- University of Jyväskylä (FI)
Publication Details
- Journal
- Physical Review Letters
- Published
- 2025-01-27
- DOI
- https://doi.org/10.1103/physrevlett.134.042501
- Citations
- 2
- Primary Topic
- Nuclear physics research studies
- Type
- article
- Field-Weighted Citation Impact
- 3.74
Funders
- European Commission
- Academy of Finland
- Horizon 2020 Framework Programme