First observation of β-delayed three-proton emission in ${}^{45}\mathrm{Fe}$

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 ${\beta }^{+}$ 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 ${}^{45}\mathrm{Fe}$ and the corresponding partial half-life are found to be $0.30\pm 0.04$ and $T_{1/2}(\beta )=8.7\pm 1.3$ ms, respectively.

Figure 1

Partial decay scheme of ${}^{45}\mathrm{Fe}$ showing some of the opened β-delayed particle emission channels. The energy scale is shown relative to the ground state of ${}^{45}\mathrm{Fe}$. The mass values were taken from Ref. [16].

Figure 2

An example of a registered β-delayed proton emission from ${}^{45}\mathrm{Fe}$. Top: An image recorded by the CCD camera. The observed track is consistent with a high energy proton. The ionizing power of the positron is too small to see its track. Bottom: The time profile of the total light intensity measured by the PMT. In the inset, a magnified part is plotted, showing in detail the decay event.

Figure 3

An example event of a β-delayed two-proton emission from ${}^{45}\mathrm{Fe}$. The description of panels is the same as in the Fig. 2.

Figure 4

An example event of a β-delayed three-proton emission from ${}^{45}\mathrm{Fe}$. The description of panels is the same as in the Fig. 2.

Figure 5

The CCD images of remaining three events of β-delayed three-proton emission from ${}^{45}\mathrm{Fe}$. The left image was taken in the mode in which a track of a ${}^{45}\mathrm{Fe}$ ion, entering the detector horizontally from the left, can be seen.