RADIATIVE LIFETIME OF THE LONG-LIVED 1S2S(3)S(1) STATE IN HELIUM-LIKE 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(-2) to 10(-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 musec is obtained for the 1s2s S-3(1) --> 1s2 S-1(0) transition in heliumlike neon, in good agreement with theoretical predictions of 91.1 and 92.0 musec.