Lifetime of the 279-kev State ofTl203

The lifetime of the first excited state of ${\mathrm{Tl}}^{203}$ at 279 kev has been measured using the delayed coincidence technique. From analysis of the exponential decay observed with an electronic time-to-pulse-height converter, the mean life was determined to be (4.05±0.08)×${10}^{-10\mathrm{}}$ sec. The decay of this state was observed using sources of ${\mathrm{Hg}}^{203}$ and ${\mathrm{Pb}}^{203}$, both sources yielding the same mean life within statistical errors. This value of the lifetime agrees very well with the recent determination by Deutsch and Metzger utilizing the resonance fluorescence method.