The Disintegration Scheme ofI131

The radiations of ${\mathrm{I}}^{131}$ have been studied with a magnetic lens spectrometer and coincidence techniques using "Kallmann" counters. Four gamma-rays of 80, 283, 363, and 638 kev were detected both by their internal conversion electrons and by photoelectrons emitted from different converters. A beta-ray spectrum of 600-kev maximum energy constitutes about 85 percent of the disintegrations and leads to a state of ${\mathrm{Xe}}^{131}$ with 363-kev excitation. In about 6 percent of the disintegrations, the transitions from this level to the ground state take place by the successive emission of an 80-kev and a 283-kev gamma-ray. Fifteen percent of the disintegrations proceed by the emission of a 315-kev beta-spectrum followed by a 638-kev gamma-ray.