Disintegration ofBa139

The nuclear radiations from ${\mathrm{Ba}}^{139}$ have been investigated with the help of a magnetic lens spectrograph and scintillation counters in coincidence. Beta rays of energy 2.380, 2.227, and 0.822 Mev have been found together with an internal conversion line from a gamma ray of energy 0.163 Mev. The photoelectron spectrum, taken in the lens, showed gamma rays of energies 0.163 and 1.43 Mev. Beta-gamma coincidence experiments, performed with scintillation counters, showed that the 2.23-Mev beta-ray group is in coincidence with the 0.163-Mev gamma ray. The 0.163-Mev line has a $\frac{K}{\mathrm{}(L+M)\mathrm{}}$ ratio of 7.0 and an internal conversion coefficient ${\alpha }_K$ of 0.22, both of which correspond to an $M1\mathrm{}$ transition. The connection with the shell model is discussed.