Excited states in ${}^{98}\mathrm{Cd}$, two proton holes from ${}^{100}\mathrm{Sn}$, were identified and studied for the first time, using in-beam spectroscopy with highly selective ancillary detectors. The structure of the $(\pi g_{9/2}{)}^{-2\mathrm{}}$ two-proton-hole spectrum below a $T_{1/2}=0.48\mathrm{}\left(16\right)\mu \mathrm{s}$ isomer is deduced and compared to shell-model predictions. A tentative $I^{\pi }=\left(8^{+}\right)$ assignment, as suggested by systematics, yields a strongly reduced $B({E2,8\mathrm{}}^{+}\to 6^{+})=0.44\mathrm{}{(}_{-10\mathrm{}}^{+20\mathrm{}})\mathrm{W}.\mathrm{u}.\mathrm{}$, corresponding to an effective proton charge of $e_{\pi }=0.85\mathrm{}{(}_{-10\mathrm{}}^{+20\mathrm{}})e$, which is at variance with existing theoretical predictions.

• Received 18 December 1996

DOI:https://doi.org/10.1103/PhysRevLett.79.2415