Lifetime of the2S13State of Heliumlike Argon (Z=18) and Heliumlike Titanium (Z=22)

The $2{}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}\to 1{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ magnetic-dipole transition in the heliumlike atoms ${\mathrm{Ar}}^{+16\mathrm{}}$ and ${\mathrm{Ti}}^{+20\mathrm{}}$ has been studied by a time-of-flight technique. The lifetime of the $2{}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}$ state is found to be 172(12)×${10}^{-9\mathrm{}}$ sec in ${\mathrm{Ar}}^{+16\mathrm{}}$ and 25.8(1.3)×${10}^{-9\mathrm{}}$ sec in ${\mathrm{Ti}}^{+20\mathrm{}}$, where the stated errors included statistical and systematic effects. These values can be compared with theoretical values of 212.4×${10}^{-9\mathrm{}}$ sec for ${\mathrm{Ar}}^{+16\mathrm{}}$ and 27.4×${10}^{-9\mathrm{}}$ sec for ${\mathrm{Ti}}^{+20\mathrm{}}$.