The measurement of the lifetimes of excited nuclear states

The experimental techniques of measuring the mean lifetimes tau of excited nuclear states is reviewed. Emphasis is put on direct measurements of tau in the region 10^-18-10^-6 s, especially on techniques involving the observation of Doppler energy shifts of gamma -rays. Indirect methods of obtaining tau by measuring the widths or partial widths are discussed. Comparisons are made of the applicability, accuracy and reliability of the different experimental techniques.