We have observed direct one-proton decay of the $({21}^{+})$ isomer in the $N=Z$ nuclide ${}^{94}\mathrm{Ag}$ into high-spin states in ${}^{93}\mathrm{Pd}$ by detecting protons in coincidence with $\gamma \mathrm{\text{−}}\gamma$ correlations and applying $\gamma$ gates based on known ${}^{93}\mathrm{Pd}$ levels. Two decay branches have been identified, with proton energies of 0.79(3) and 1.01(3) MeV and branching ratios of 1.9(5)% and 2.2(4)%, respectively. The corresponding partial half-life values are 21(6) and 18(4) s. The $Q$ value of the direct proton decay of the $({21}^{+})$ isomer was found to be 5.78(3) MeV. The very small reduced widths of the observed proton decays might reflect dominating collective configurations in the $({21}^{+})$ isomer, and the fine structure of the proton spectrum might indicate a strong deformation of this state.

• Received 29 March 2005

DOI:https://doi.org/10.1103/PhysRevLett.95.022501