The new isotope ${}_{}{}^{60}{}_{}{}^{}\mathrm{Mn}$ was produced by bombarding ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ with ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ ions at $E_{{}_{}{}^{18}{}_{}{}^{}\mathrm{O}}=50\mathrm{}-70$ MeV. The $\beta$-decay scheme of ${}_{}{}^{60}{}_{}{}^{}\mathrm{Mn}$ was determined from $\gamma$-ray singles and $\gamma -\gamma$ coincidence experiments using large Ge(Li) detectors. The half life of ${}_{}{}^{60}{}_{}{}^{}\mathrm{Mn}$ was found to be 1.79 ± 0.10 s. A new level with excitation energy 2792 keV was observed in the daughter, ${}_{}{}^{60}{}_{}{}^{}\mathrm{Fe}$. The ground-state spin and parity of ${}_{}{}^{60}{}_{}{}^{}\mathrm{Mn}$ was determined to be $3^{+}$ and its total decay energy $Q_{\beta }$ was measured to be 8.51 ± 0.10 MeV. This corresponds to a mass excess of - 52.89 ± 0.10 MeV, which is compared with various predictions. The structure of ${}_{}{}^{60}{}_{}{}^{}\mathrm{Fe}$ as determined from the present work and from previous experiments is compared with a shell-model calculation.

RADIO ACTIVITY ${}_{}{}^{60}{}_{}{}^{}\mathrm{Mn}$: measured $T_{\frac{1}{2}}$, $E_{\gamma }$, $I_{\gamma }$, $E_{\beta }$, $\gamma -\gamma$ coin, $\beta -\gamma$ coin; deduced decay scheme, $log\mathrm{ft}$, mass excess, g.s. $J^{\pi }$. ${}_{}{}^{60}{}_{}{}^{}\mathrm{Fe}$: deduced levels. Enriched targets, Ge(Li) detectors, plastic scintillator, multiple rabbit.

• Received 6 March 1978

DOI:https://doi.org/10.1103/PhysRevC.17.2176