2025

Mukai, M.; Hirayama, Y.; Schury, P.; Watanabe, Y. X.; Hashimoto, T.; Hinohara, N.; Jeong, S. C.; Miyatake, H.; Moon J., Y.; Niwase, T.; Reponen, M.; Rosenbusch, M.; Ueno, H.; Wada, M.

Precise mass measurements of refractory nuclei produced by multinucleon transfer reactions of a⁢ 136Xe beam and natIr target were conducted at the KISS (KEK Isotope Separation System) facility, using a multireflection time-of-flight mass spectrograph. The study encompasses ions with mass numbers 𝐴=188,189,190,192, and atomic numbers 𝑍=74–79. Our findings show good agreement between the evaluated masses, excluding 192Re, and known values, within the specified error margins. The assessment includes the reevaluation of the rejected mass value for 189W in the AME2020 atomic mass evaluation. The determined atomic mass of 189W aligns closely with previously reported values obtained through direct mass measurements using the GSI storage ring ESR and 𝛽-decay 𝑄-value measurements. The flat 𝑆2⁢n pattern between 189W and 190W was interpreted as a result of a shape transition at 𝑁=116 according to Hartree-Fock-Bogoliubov calculations with the SV-min parametrization. Additionally, the updated mass value for 192Re also suggests a shape transition at 𝑁=117, consistent with previous studies.