A new method for precision measurements of atomic lifetimes by laser excitation of fast beams is described which is expected to allow accuracies of $\frac{\Delta \tau }{\tau }={10}^{-3\mathrm{}}$. A first application to ${\mathrm{Ba}}^{+}-6\mathrm{}{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ yields as a preliminary result $\tau =6.21\mathrm{}\pm 0.06$ nsec.

• Received 21 May 1973

DOI:https://doi.org/10.1103/PhysRevLett.31.501