MEASUREMENT OF THE RADIATIVE LIFETIME OF THE 1S2S S-3(1) LEVEL IN HELIUM-LIKE MAGNESIUM

We apply a recently developed electron-beam ion trap technique to measure the lifetime of the 1s2s S-3(1) level in heliumlike magnesium. The technique employs a fast-switching electron beam to produce and excite electrostatically trapped ions. The radiative lifetime is determined by observing the fluorescent decay of the 1s2s S-3(1) level after the beam energy is switched below the threshold for electron-impact excitation. A value of 13.61+/-0.49 mu s has been measured for the 1s2s S-3(1) level in heliumlike magnesium, in good agreement with theoretical predictions.