Decay Studies of Iodine-118 and -120

Abstract

The radioactive decay of iodine-118 ground and isomeric state and iodine-120 ground and isomeric state from irradiations of silver with carbon-12 ions, palladium with nitrogen-14 ions, and cadmium with boron-11 ions has been studied with a germanium lithium-drifted detector, a NaI crystal, an anthracene crystal, and several 400-channel analyzers. The electron and $\ensuremath{\gamma}$ spectra, and singles and coincidence spectra, have been interpreted. Tentative decay schemes for the iodine-118 ground state and isomeric state as well as the iodine-120 ground state and isomeric state are given. The half-life of ${\mathrm{I}}^{118g}$ was found to be 13.0\ifmmode\pm\else\textpm\fi{}0.3 min ($\ensuremath{\gamma}$-ray energies: 542, 605, and 1147 keV, ${\ensuremath{\beta}}^{+}$ endpoint energy: 6.05 MeV). The half-life of the isomeric state was found to be 8.5\ifmmode\pm\else\textpm\fi{}0.5 min ($\ensuremath{\gamma}$-ray energies: 600 and 612 keV). The half-life of ${\mathrm{I}}^{120g}$ was found to be 83\ifmmode\pm\else\textpm\fi{}4 min ($\ensuremath{\gamma}$-ray energies: 560, 640, 1520, and 1540 keV, ${\ensuremath{\beta}}^{+}$ endpoint energies: 3.45 and 2.9 MeV). The half-life of the isomeric state was found to be 53\ifmmode\pm\else\textpm\fi{}4 min ($\ensuremath{\gamma}$-ray energies: 600 and 612 keV, ${\ensuremath{\beta}}^{+}$ endpoint energy: 3.85 MeV). A comparison of the levels of ${\mathrm{Te}}^{118,120,122,124,126}$ is given.