First observation of β-delayed three-proton emission in ⁴⁵Fe

The decay of extremely neutron deficient ⁴⁵Fe 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 β⁺ decay channels accompanied by proton emission were clearly identified. In addition to β-delayed one-proton and β-delayed two-proton decays, β-delayed three-proton emission was recorded which represents the first direct and unambiguous observation of this decay channel. The branching ratio for the β decay of ⁴⁵Fe and the corresponding partial half-life are found to be 0.30±0.04 and T_1/2(β)=8.7±1.3 ms, respectively.