Disintegration ofTe131

Investigations of the nuclear radiations from the 30-hour isomeric state of ${\mathrm{Te}}^{131}$ have been made with the help of magnetic lens spectrometers and scintillation counters. Beta-ray groups of end-point energies 2.46, 2.14, 1.69, 1.35, 0.98, 0.57, and 0.42 Mev have been found. The well-known internally converted 0.180-Mev transition, that from the 30-hour isomeric state of ${\mathrm{Te}}^{131}$ to the 25-minute ground state, was reinvestigated, and its $\frac{K}{\mathrm{}(L+M)\mathrm{}}$ ratio of 2.4 corresponds to that of an $M4\mathrm{}$ transition. Photoelectron spectra show well defined lines corresponding to gamma-ray energies of 0.773, 0.446, 0.331, 0.147, and 1.12 Mev, and weaker lines corresponding to gamma-ray energies of 0.24, 0.275, 0.575, 0.84, and 1.63 Mev. Gray wedge pictures of NaI(Tl) scintillation spectra indicate that the 0.147 and 0.446-Mev transitions are the main lines appearing in the 25-minute tellurium with the 0.773-Mev line also visible. Gamma-gamma scintillation coincidence experiments on the long-lived tellurium are utilized in establishing a possible decay scheme.