The decay of ${\mathrm{Ba}}^{129}$ produced by an ($n, 2n$) reaction has been investigated. A new half-life value of 2.45±0.05 hours is reported. Gamma rays of 1.45, 0.210, 0.182, and 0.127 Mev with relative intensities 42, 65, 100, and ∼26 were found, with coincidences between the 1.45-Mev and 0.182-Mev gammas. Milking experiments showed 25% to 30% of ${\mathrm{Ba}}^{129}$ to decay by ${\beta }^{+}$ emission, based on assumptions about the unknown decay scheme of ${\mathrm{Cs}}^{129}$. This result is compatible with the intensities of $K$ x-rays, positrons, and the various gamma rays only if unobserved $\gamma -\gamma$ coincidence are postulated in addition to the reported ones. The result of the milking experiments is also in contradiction to the calculated $\frac{K}{{\beta }^{+}}$ ratio. 19% of the observed ${\beta }^{+}$ transitions are in coincidence with the 0.210 and 5.6% with the 0.127-Mev gamma rays. Because of the mentioned discrepancies, no decay scheme can be proposed.

• Received 8 October 1958

DOI:https://doi.org/10.1103/PhysRev.113.863