A new application of the delayed coincidence technique for measuring short nuclear lifetimes has been developed which is basically similar to the well-known prompt comparison method. Systematic errors can be reduced and greater accuracy obtained for nuclei which exhibit both a prompt and a delayed event. A transistorized time-to-amplitude converter was used. The mean life of the second excited state of ${\mathrm{Ca}}^{42}$ [(4.8±0.3)×${10}^{-10\mathrm{}}$ sec] and the first excited state of ${\mathrm{Sc}}^{47}$ (<5×${10}^{-12\mathrm{}}$ sec) were measured. Also the mean life of the first excited state of ${\mathrm{Hg}}^{198}$ [(3.5±0.5)×${10}^{-11\mathrm{}}$ sec] was determined by the usual self-comparison method.

• Received 11 October 1960

DOI:https://doi.org/10.1103/PhysRev.121.1169