The time which elapses between excitation of an atom by a pulse of light and subsequent emission of radiation may be measured by a delayed coincidence technique. A system which is suitable for measuring lifetimes of atomic states in the range 10-7–10-8 sec, employing a high speed Kerr shutter in conjunction with a time-to-pulse height converter and kicksorter, is described.
E. E. Habib, B. P. Kibble, and G. Copley, "An Apparatus for the Precise Determination of Lifetimes of Atomic States," Appl. Opt. 7, 673-675 (1968)