The activities ${}_{}{}^{101}{}_{}{}^{}\mathrm{Mo}$ and ${}_{}{}^{101}{}_{}{}^{}\mathrm{Tc}$ produced from neutron capture by natural Mo were chemically separated and studied using Ge(Li) $\gamma$-ray detectors. Out of 185 transitions observed in the decay of ${}_{}{}^{101}{}_{}{}^{}\mathrm{Mo}$, 170 were assigned to 44 excited levels in ${}_{}{}^{101}{}_{}{}^{}\mathrm{Tc}$. For the decay of ${}_{}{}^{101}{}_{}{}^{}\mathrm{Tc}$, 26 of 27 transitions were placed among 10 excited levels in ${}_{}{}^{101}{}_{}{}^{}\mathrm{Ru}$. The interpretation of the ${}_{}{}^{101}{}_{}{}^{}\mathrm{Tc}$ level scheme using the shell-model approach is not satisfactory even for a five-particle calculation. Systematics of odd-$A$ level structures in the region of $A=101\mathrm{}$ indicate that the level structure of ${}_{}{}^{101}{}_{}{}^{}\mathrm{Tc}$ could be due partly to the onset of collective effects.

RADIOACTIVITY ${}_{}{}^{101}{}_{}{}^{}\mathrm{Mo}$, ${}_{}{}^{101}{}_{}{}^{}\mathrm{Tc}$ [from natural $\mathrm{Mo}(n, \gamma )$]; measured $E_{\gamma }$, $I_{\gamma }$, $\gamma -\gamma$ coin; deduced levels, $logft\text{'}\mathrm{s}$, $J$, $\pi$.

• Received 14 April 1975

DOI:https://doi.org/10.1103/PhysRevC.12.572