The nuclide ${}^{266}\mathrm{Bh}$ was produced in the ${}^{248}\mathrm{Cm}({}^{23}\mathrm{Na},5n){}^{266}\mathrm{Bh}$ reaction at beam energies of 125.9, 130.6, and 135.3 MeV. Decay properties of ${}^{266}\mathrm{Bh}$ were investigated with a rotating wheel apparatus for $\alpha$ and spontaneous fission (SF) spectrometry under low background conditions attained by a gas-jet transport system coupled to the RIKEN gas-filled recoil ion separator. Based on genetically correlated $\alpha \text{−}\alpha$ and $\alpha$-SF decay chains, a total of 23 chains were assigned to ${}^{266}\mathrm{Bh}$ and its daughter nuclide ${}^{262}\mathrm{Db}$ and granddaughter ${}^{258}\mathrm{Lr}$. The half-life of ${}^{266}\mathrm{Bh}$ was measured to be $T_{1/\phantom{12}2}=10.0_{-1.7}^{+2.6}\mathrm{s}$ which is an order of magnitude longer than the literature data. The $\alpha$-particle energies of ${}^{266}\mathrm{Bh}$ disperse widely in the range of $E_{\alpha }=8.62–9.40\mathrm{MeV}$. The maximum production cross section for the ${}^{248}\mathrm{Cm}({}^{23}\mathrm{Na},5n){}^{266}\mathrm{Bh}$ reaction was determined to be $\sigma =57\pm 14$ pb at 130.6 MeV, whereas the upper limit for the ${}^{248}\mathrm{Cm}$(${}^{23}\mathrm{Na},4n$)${}^{267}\mathrm{Bh}$ reaction was $\sigma \le 14$ pb at 121.2 MeV. These cross sections are discussed by comparing with the literature data as well as the theoretical calculations.

• Received 11 June 2020
• Accepted 30 July 2020

DOI:https://doi.org/10.1103/PhysRevC.102.024625