Structure ofTc94

The level structure and decay properties of levels in ${}_{}{}^{94}{}_{}{}^{}\mathrm{Tc}$ up to 2307 keV of excitation have been investigated via measurements of excitation functions of singles $\gamma$ rays and via $n\gamma$- and $\gamma \gamma$-coincidence experiments following the ${}_{}{}^{94}{}_{}{}^{}\mathrm{Mo}$ ($p$,$n\gamma$) reaction with proton energies between 5.0 and 8.0 MeV. From these experiments and from high resolution singles energy and directional-correlation measurements an extended decay scheme has been obtained which included 42 levels in ${}_{}{}^{94}{}_{}{}^{}\mathrm{Tc}$ and incorporated 180 $\gamma$ rays. New levels at 797.9 ($2^{-}$), 823.2($2^{+}$), 917.7($3^{+}$), 926.3($4^{+}$), 953.5($3^{-}$), 1045.1($2^{+}$), 1178.4($2^{-}$,$3^{-}$), 1263.9($3^{+}$), 1314.1($4^{\mathrm{}(-)\mathrm{}}$), 1351.7($3^{-}$), 1364.9($2^{+}$), 1394.2($3^{-}$), 1406.8($3^{+}$), 1429.3($1^{+}$), 1540.0($3^{+}$), 1659.9, 1679.0, 1778.4, 1856.8, 1865.2, 1884.0, 1973.5, 2002.1, 2094.4, 2131.8, 2167.0, 2208.2, 2213.5, 2241.6, 2264.4, 2267.8, and 2306.6 keV with the assigned $J^{\pi }$ values in parentheses were postulated. The singles directional correlations for many transitions provided (i) reliable branching ratios, (ii) $J^{\pi }$ assignments, and (iii) multipole mixing ratios from analysis of the correlations via the compound statistical theory for nuclear reactions. Lifetimes for 18 states in ${}_{}{}^{94}{}_{}{}^{}\mathrm{Tc}$ were obtained by the Doppler-shift-attenuation method via the ${}_{}{}^{94}{}_{}{}^{}\mathrm{Mo}$($p$,$n\gamma$) reaction at 7.2 MeV. The lifetimes were extracted from singles spectra taken in the presence of standards at eight angles between 0° and 110° to the beam direction by employing a centroid shift analysis of the data. For a good number of transitions in ${}_{}{}^{94}{}_{}{}^{}\mathrm{Tc}$ values or limits for $B\left(E1\right)$, $B\left(E2\right)$, and $B\left(M1\right)$ were obtained. The positive-parity levels up to 1.711 MeV of excitation and their decay properties were calculated in the shell-model framework and are compared with the corresponding experimental quantities.