Weak decays in superheavy nuclei

Abstract

Superheavy nuclei represent the heaviest atoms and nuclides known at the limit of mass and charge. The observed superheavy nuclei are all proton-rich; they decay primarily by emitting $\alpha$ particles and fission, with a possible small electron capture (EC) branch. Due to the huge atomic numbers and associated relativistic effects, EC-decays of superheavy systems are expected to differ from what is known in lighter nuclei. In this paper, using the quantified relativistic nuclear density functional theory and the quasiparticle random-phase approximation with the interaction optimized to experimental ${\beta }^{-}$-decay half-lives and Gamow-Teller resonance energies, we study the EC/${\beta }^{\pm }$-decays in $Z=101-118$ nuclei. Both allowed ($1^{+}$) and first-forbidden ($0^{-},1^{-}$ and $2^{-}$) transitions are considered. We show that the first-forbidden $1^{-}$ transitions dominate the decay rates in almost all studied nuclei. For proton-rich nuclei, EC dominates over ${\beta }^{+}$ decay. We identify 44 nuclei with EC/${\beta }^{+}$ branching ratio larger than 5\%, indicating a possible competition with $\alpha$-decay and spontaneous fission channels.

Comments: 7 pages, 4 figures, submitted for publication