First observation of β-delayed three-proton emission inFe45

The decay of extremely neutron deficient $^{45}\mathrm{Fe}$ has been studied by means of a new type of a gaseous detector in which a technique of digital imaging was used to record tracks of charged particles. The ${\ensuremath{\beta}}^{+}$ decay channels accompanied by proton emission were clearly identified. In addition to \ensuremath{\beta}-delayed one-proton and \ensuremath{\beta}-delayed two-proton decays, \ensuremath{\beta}-delayed three-proton emission was recorded which represents the first direct and unambiguous observation of this decay channel. The branching ratio for the \ensuremath{\beta} decay of $^{45}\mathrm{Fe}$ and the corresponding partial half-life are found to be $0.30\ifmmode\pm\else\textpm\fi{}0.04$ and ${T}_{1/2}(\ensuremath{\beta})=8.7\ifmmode\pm\else\textpm\fi{}1.3$ ms, respectively.