Speaker
Description
Excited states with high $K$ quantum numbers provide valuable information on the underlying nuclear structure. Due to the conservation of the $K$ quantum number in deformed nuclei, transitions requiring large changes in $K$ are strongly hindered, and thus those excited states exist as isomers [1,2]. Of special interest are superheavy nuclei, where the high-$K$ states are significantly stable against fission [3,4]. This enables access to nuclei whose ground states would otherwise be too short-lived to be experimentally studied [5].
$K$ isomers are spread over in nobelium ($Z=102$) and rutherfordium ($Z=104$) isotopes; however, in the heavier elements, only two $\alpha$-decaying cases have been observed [$^{270}$Ds ($Z=110$) and $^{266}$Hs ($Z=108$)] [2]. Only recently, at TASCA, a strong indication of a $K$-isomeric state was observed in a seaborgium ($Z=106$) isotope, i.e., in $^{259}$Sg [6].
Inspired by this observation [6], all experimental data on seaborgium isotopes accumulated at SHIP during 2003-2009 were revisited. In this talk we will present the results from the reanalysis of those experimental data.
References
[1] P. Walker and G. Dracoulis, Nature 399, 35 (1999).
[2] D. Ackermann, S. Antalic and F. P. Heßberger, Eur. Phys. J. Spec. Top. 233, 1017 (2024).
[3] F. R. Xu et al., Phys. Rev. Lett. 92, 252501 (2004).
[4] J. Khuyagbaatar, Eur. Phys. J. A 58, 243 (2022).
[5] J. Khuyagbaatar, P. Mosat, et al., Phys. Rev. Lett. 134, 022501 (2025).
[6] P. Mosat, J. Khuyagbaatar, et al., Phys. Rev. Lett. 134, 232501 (2025).