Disintegration ofI126

The radiations from ${\mathrm{I}}^{126}$ have been investigated with a scintillation coincidence spectrometer; $\beta -\gamma$, $\gamma -\gamma$, and $x-\gamma$ events were studied. In a fraction of the electron-capture disintegrations, a gamma ray of energy 0.74 Mev was found to occur in cascade with the previously known 0.65-Mev gamma ray. The crossover transition also was observed. In a fraction of the negative beta-decay processes, a gamma ray of energy 0.48 Mev occurs in cascade with the previously known 0.38-Mev gamma ray; in addition, the crossover transition was observed. The maximum energy of the positron spectrum and the relative intensities of all gamma transitions and of the annihilation radiation were measured. The intensity information, combined with the previously measured ratio of electron-capture probability to beta-decay probability and with the ratio of the intensities of the 0.85-Mev and 1.24-Mev beta rays, is sufficient to give the abundances of all observed transitions in the decay scheme. Both the $\mathrm{ft}$ values and the measured ratio of electron-capture probability to positron-emission probability for the ground-state transitions indicate that ${\mathrm{I}}^{126}$ has spin 2 and negative parity. The shell structure assignments, neutron $h_{\frac{11}{2}}$ and proton $g_{\frac{7}{2}}$, are the only ones which can couple to give the resultant spin 2 and negative parity.