Hyperfine quenching and precision measurement of the 2P03-23P1fine-structure splitting in heliumlike gadolinium (Gd62+)

The hyperfine-quenched transition $2^3$ ${\mathit{P}}_{0\mathrm{-}}$ $1^1$ ${\mathit{S}}_0$ has been observed in heliumlike gadolinium (${\mathrm{Gd}}^{62+}$) in the two isotopes ${}_{}{}^{155}{}_{}{}^{}\mathrm{Gd}$ and ${}_{}{}^{157}{}_{}{}^{}\mathrm{Gd}$. The lifetime for the transition (${\mathrm{\tau }}_0$) has been measured for each isotope and found to be ${\mathrm{\tau }}_0$(155)=13.43(27)×${10}^{\mathrm{-}12}$ sec and ${\mathrm{\tau }}_0$(157)=7.65(55)×${10}^{\mathrm{-}12}$ sec. From the measured lifetimes a value is inferred for the absolute value of the $2^3$ ${\mathit{P}}_{0\mathrm{-}}$ $2^3$ ${\mathit{P}}_1$ fine-structuring splitting ‖Δ${\mathit{E}}_{0\mathrm{-}1}$‖ in ${\mathrm{Gd}}^{62+}$ with the result ‖Δ${\mathit{E}}_{0\mathrm{-}1}$‖=18.57(19) eV, where the error represents 1 standard deviation. This result is compared with calculations based on the multiconfiguration Dirac-Fock method and on the unified method.