Double Electron Ejection in the Decay ofBa137

Simultaneous ejection of two electrons in the decay of the 662-keV state of ${}_{}{}^{137}{}_{}{}^{}\mathrm{Ba}$ has been investigated by means of two Si(Li) detectors and a two-dimensional pulse-height analyzer. The $\mathrm{KK}$ process has been observed, while for the $K$, $L+M+\dots$ processes only an upper limit has been determined. The results obtained are $\frac{T_{\mathrm{KK}}}{T_K}=(1.8\mathrm{}\pm 0.5)\times {10}^{-4\mathrm{}}$ and $\frac{T_{K,L+M+\cdots }}{T_K}<~4.5\times {10}^{-4\mathrm{}}$. The comparison of the experimental results with the existing theories indicates that the process proceeds primarily via electronic intermediate states.