Beta Decay ofAg111

A new very weak $\beta$ group 414 ± 10 (0.9%) keV is revealed in addition to the three $\beta$ groups with end points 1035 ± 2 (92%), 789 (1.1%), and 693 ± 3 (6.0%). The 414-keV $\beta$ group feeds the 621-keV level of ${\mathrm{Cd}}^{111}$ introduced by Sastry, Lakshminarayana, and Jnanananda. The large shape deviation (17%) reported by Langer et al. for the 693-keV $\beta$ group indicated a breakdown of the $\xi$ approximation for this group, whereas correlation experiments and theoretical predictions indicated statistical shape. The present measurement $C\left(W\right)=k[1-(0.01\mathrm{}\pm 0.06\left)W\right]$ confirms the latter conclusions and is in quantitative agreement with the shell-model predictions of Delabaye, Deutsch, and Lipnik. The characteristics of ${\mathrm{½}}^{-}$ → ${\mathrm{½}}^{+}$ and ${\mathrm{½}}^{-}$ → ${\frac{3}{2}}^{+}$ transitions are just similar to those of ${\mathrm{Mo}}^{99}$ and a theoretical fit of the outer $\beta$ group of ${\mathrm{Ag}}^{111}$ yields $3.2<~\Lambda <~3.3$ and $1.2<~{\Lambda }_0<~1.4$.