First high-precision direct determination of the atomic mass of a superheavy nuclide

P. Schury, T. Niwase, M. Wada, P. Brionnet, S. Chen, T. Hashimoto, H. Haba, Y. Hirayama, D. S. Hou, S. Iimura, H. Ishiyama, S. Ishizawa, Y. Ito, D. Kaji, S. Kimura, H. Koura, J. J. Liu, H. Miyatake, J. Y. Moon, K. MorimotoKosuke Morita, D. Nagae, M. Rosenbusch, A. Takamine, Y. X. Watanabe, H. Wollnik, W. Xian, S. X. Yan

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


We present the first direct measurement of the atomic mass of a superheavy nuclide. Atoms of Db257 (Z=105) were produced online at the RIKEN Nishina Center for Accelerator-Based Science using the fusion-evaporation reaction Pb208(V51, 2n)Db257. The gas-filled recoil ion separator GARIS-II was used to suppress both the unreacted primary beam and some transfer products, prior to delivering the energetic beam of Db257 ions to a helium gas-filled ion stopping cell wherein they were thermalized. Thermalized Db3+257 ions were then transferred to a multireflection time-of-flight mass spectrograph for mass analysis. An alpha particle detector embedded in the ion time-of-flight detector allowed disambiguation of the rare Db3+257 time-of-flight detection events from background by means of correlation with characteristic α decays. The extreme sensitivity of this technique allowed a precision atomic mass determination from 11 events. The mass excess was determined to be 100063(231)stat(132)syskeV/c2. Comparing to several mass models, we show the technique can be used to unambiguously determine the atomic number as Z=105 and should allow similar evaluations for heavier species in future work.

Original languageEnglish
Article numberL021304
JournalPhysical Review C
Issue number2
Publication statusPublished - Aug 2021

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics


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