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Discovery of K-isomeric states in seaborgium isotopes

P. Mošať1,*, B. Andel2, J. Khuyagbaatar1, D. Ackermann1,†, S. Antalic2, S. Heinz1, I. Kojouharov1, P. Kuusiniemi1,‡, M. Mazzocco1,§ et al.

J. Mišt2, K. Nishio3, B. Streicher1, B. Sulignano1,∥, and F. P. Heßberger1

  • *Contact author: p.mosat@gsi.de
  • †Present address: GANIL, 14076 Caen CEDEX 5, France.
  • ‡Present address: Muon Solutions Oy, Pyhäsalmi, Finland.
  • §Present address: INFN - Sezione di Padova, 35121 Padova, Italy.
  • ∥Present address: CEA, Centre de Saclay, IRFU/Service de Physique Nucléaire, F-91191 Gif-sur-Yvette, France.
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Phys. Rev. C 114, 034321 – Published 16 September, 2026

DOI: https://doi.org/10.1103/gsw6-37t3

Abstract

The K-isomeric states in the heaviest nuclei are among the interesting topics in superheavy-element research. In the present work, we report on the discovery of µs isomers in Sg258,259,260 which deexcite with half-lives of 120−55+578µs, 85±6µs, and 8.5−1.8+3.1µs, respectively, and are attributed to high-K states formed in multiquasiparticle couplings. In Sg261, activity with 12.6−1.6+2.2µs half-life was observed and it is suggested to originate from decays of a high-K multiquasiparticle and/or single-particle isomeric states.

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Phys. Rev. C 114, 034321– Published 16 September, 2026
  • Received 30 April 2026
  • Accepted 27 July 2026
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