Radiative lifetime of the long-lived 1s2s3S1state in heliumlike neon by electron-beam excitation of trapped ions

We report a technique for measuring the lifetimes of long-lived excited levels in highly charged ions that fall into the range from ${10}^{\mathrm{-}2}$ to ${10}^{\mathrm{-}7}$ sec, inaccessible to existing methods. Employing a fast-switching electron beam to produce and excite electrostatically trapped ions, lifetimes are determined by observing the fluorescent decay of metastable levels. A value of 90.5±1.5 μsec is obtained for the 1s2s ${}_{}{}^3{}_{}{}^{}$ ${\mathit{S}}_1$→1${\mathit{s}}^2$ ${}_{}{}^1{}_{}{}^{}$ ${\mathit{S}}_0$ transition in heliumlike neon, in good agreement with theoretical predictions of 91.1 and 92.0 μsec.