The branching ratio of the $0^{+}$ state of ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ at 2561 keV for decay by $e^{+}-e^{-}$ pair emission to the $0^{+}$ ground state is measured to be (0.17 ± 0.025)%. The lifetime of this third excited state of ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ is not known; the main decay mode is by $E2\mathrm{}$ decay to the 1408-keV $2^{+}$ first excited state. In addition $\gamma$-ray spectra were measured with a Ge(Li) detector and excitation energies and branching ratios were determined for levels up to 3.834 MeV.

• Received 25 May 1972

DOI:https://doi.org/10.1103/PhysRevC.6.1224