Structure of Superheavy Nuclei Along Element 115 Decay Chains

Abstract

A recent high-resolution $\hat{I}\pm$, $X$-ray, and ${\hat{I}}^3$-ray coincidence-spectroscopy experiment offered first glimpse of excitation schemes of isotopes along $\hat{I}\pm$-decay chains of $Z=115$. To understand these observations and to make predictions about shell structure of superheavy nuclei below ${}^{288}115$, we employ two complementary mean-field models: self-consistent Skyrme Energy Density Functional approach and the macroscopic-microscopic Nilsson model. We discuss the spectroscopic information carried by the new data. In particular, candidates for the experimentally observed $E1$ transitions in ${}^{276}$Mt are proposed. We find that the presence and nature of low-energy $E1$ transitions in well-deformed nuclei around $Z=110,N=168$ strongly depends on the strength of the spin-orbit coupling; hence, it provides an excellent constraint on theoretical models of superheavy nuclei. To clarify competing theoretical scenarios, an experimental search for $E1$ transitions in odd-$A$ systems ${}^{275,277}$Mt, ${}^{275}$Hs, and ${}^{277}$Ds is strongly recommended.

9 pages, 8 figures, 6 table; accepted for publication in Physical Review C