Prominent bump in the two-neutron separation energies of neutron-rich lanthanum isotopes revealed by high-precision mass spectrometry

Abstract

We report on high-precision atomic mass measurements of ${}^{148\text{-}153}$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 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 call for further studies to elucidate the structure of neutron-rich lanthanum isotopes.

arXiv comment9 pages, 4 figures

References in corpus (23)

• Nuclear ground-state masses and deformations: FRDM(2012)
• Origin of the Heaviest Elements: the Rapid Neutron-Capture Process
• Nuclear energy density optimization: Large deformations
• Evolution of shell structure in exotic nuclei
• Unexpectedly large charge radii of neutron-rich calcium isotopes
• Quantum Phase Transition in the Shape of Zr isotopes
• A sextupole ion beam guide to improve the efficiency and beam quality at IGISOL
• Charge radii of exotic potassium isotopes challenge nuclear theory and the magic character of $N=32$
• Probing the N = 32 shell closure below the magic proton number Z = 20: Mass measurements of the exotic isotopes 52,53K
• New precision mass measurements of neutron-rich calcium and potassium isotopes and three-nucleon forces
• Landscape of pear-shaped even-even nuclei
• Formation Of The Rare Earth Peak: Gaining Insight Into Late-Time r-Process Dynamics
• Influence of nuclear physics inputs and astrophysical conditions on Th/U chronometer
• Mass measurements near the $r$-process path using the Canadian Penning Trap mass spectrometer
• Precision mass measurements on neutron-rich rare-earth isotopes at JYFLTRAP - reduced neutron pairing and implications for the $r$-process calculations
• Precise atomic masses of neutron-rich Br and Rb nuclei close to the r-process path
• Underlying structure of collective bands and self-organization in quantum systems
• Penning-trap mass spectrometry of highly charged, neutron-rich Rb and Sr isotopes in the vicinity of $A\approx 100$
• Precision mass measurements of neutron-rich scandium isotopes refine the evolution of $N=32$ and $N=34$ shell closures
• A new study of the $N=32$ and $N=34$ shell gap for Ti and V by the first high-precision MRTOF mass measurements at BigRIPS-SLOWRI
• Mass measurements of neutron-rich Rb and Sr isotopes
• Precision mass measurements in the zirconium region pin down the mass surface across the neutron midshell at $N=66$
• Probing the N=104 midshell region for the r process via precision mass spectrometry of neutron-rich rare-earth isotopes with the JYFLTRAP double Penning trap

Cited by in corpus (1)

• Level structure of light neutron-rich La isotopes beyond the N=82 shell closure