Phys.Rev.Lett. 136, 232501 (2026)

S.Kimura, M.Wada, H.Haba, Y.Hirayama, H.Ishiyama, Y.Ito, T.Niwase, M.Rosenbusch, P.Schury, H.Ueno, Y.X.Watanabe, Y.Yamanouchi

New Ground State in ¹⁴⁹La Removes Two-Neutron-Separation-Energy Anomaly in Lanthanum Isotopes

ATOMIC MASSES ¹⁴⁹Nd, ¹⁴⁹Pr, ¹⁴⁹La, ¹⁴⁹Ba [from ²⁵²Cf, ²⁴⁸Cm(SF)]; measured TOF, Eγ, Iγ; deduced mass excess values, T_1/2, two-neutron separation energies, a nuclear shape transition from octupole deformation to another type of deformation occurs around N=91 is likely the cause of this kink structure using a multireflection time-of-flight mass spectrograph (MRTOF-MS) at RIKEN combined with a β-TOF detector. Comparison with available data, FRDM calculations.

doi: 10.1103/gvxl-vxd4