The nuclide ${}^{262}\mathrm{Db}$ was produced in the ${}^{248}\mathrm{Cm}$(${}^{19}\mathrm{F}$,5$n$)${}^{262}\mathrm{Db}$ reaction at beam energies of 103.1 and 97.4 MeV. Decay properties of ${}^{262}\mathrm{Db}$ were investigated with a rotating wheel apparatus for α 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 α-α and α-SF decay chains, a total of 76 chains were assigned to ${}^{262}\mathrm{Db}$ and its α-decay daughter nuclide ${}^{258}\mathrm{Lr}$. No correlated decay chain was observed for Db produced in the ${}^{248}\mathrm{Cm}$(${}^{19}\mathrm{F}$,4$n$)Db reaction and its daughter Lr. The half-lives of ${}^{262}\mathrm{Db}$ and ${}^{258}\mathrm{Lr}$ were measured to be $T_{1/2}=33.8_{-3.5}^{+4.4}$ and $3.{54}_{-0.36}^{+0.46}\mathrm{s}$, respectively, and they confirmed the literature data. The α-particle energy $\left(E_{\alpha }\right)$ and intensity ($I_{\alpha }$) of ${}^{262}\mathrm{Db}$ were revised to $E_{\alpha }$ = 8.46 ± 0.04 MeV ($I_{\alpha }$ = 70 ± 5%) and $E_{\alpha }$ = 8.68 ± 0.03 MeV ($I_{\alpha }$ = 30 ± 5%). The SF activity with $T_{1/2}$ = 30.2 ± 6.1 s was assigned to ${}^{262}\mathrm{Db}$, and the SF branch of ${}^{262}\mathrm{Db}$ was determined to be $b_{\mathrm{SF}}$ = 52 ± 4%. From an observation of two SF decays which correlated to the α decay of ${}^{262}\mathrm{Db}$, an electron capture (EC) decay with $b_{\mathrm{EC}}$ = 2.6 ± 1.8% was suggested in ${}^{258}\mathrm{Lr}$. The production cross sections for the ${}^{248}\mathrm{Cm}$(${}^{19}\mathrm{F}$,5$n$)${}^{262}\mathrm{Db}$ reaction were determined to be 2.1 ± 0.7 nb at 103.1 MeV and $0.{23}_{-0.11}^{+0.18}\mathrm{nb}$ at 97.4 MeV, whereas, those for the ${}^{248}\mathrm{Cm}$(${}^{19}\mathrm{F}$,4$n$)Db reaction were the upper limits of ≤0.064 nb at 103.1 MeV and ≤0.13 nb at 97.4 MeV. These cross sections are discussed by comparing with the literature data as well as the theoretical prediction.

• Received 29 December 2013

DOI:https://doi.org/10.1103/PhysRevC.89.024618