Decay schemes of 45.3-d ${}_{}{}^{237}{}_{}{}^{}\mathrm{Pu}$ and 1.55×${10}^5$ yr ${}_{}{}^{236}{}_{}{}^{}\mathrm{Np}$ have been investigated by measuring their $\gamma$ ray and conversion electron spectra with a 5-${\mathrm{cm}}^2$×1-cm Ge detector and a cooled Si(Li) spectrometer, respectively. Intensities of $\gamma$ rays, x rays, and conversion electrons have been determined and these have been used to derive $log\mathrm{ft}$ values for EC and ${\beta }^{-}$ transitions. In addition to confirming previously known level schemes in ${}_{}{}^{237}{}_{}{}^{}\mathrm{Np}$ and ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$, the energies of the 4 + →2 + and 6 + →4 + transitions in the ${}_{}{}^{236}{}_{}{}^{}\mathrm{Pu}$ ground state band have been determined. Relative intensities of x rays in the decay of ${}_{}{}^{235}{}_{}{}^{}\mathrm{Np}$ have also been measured.

RADIOACTIVITY ${}_{}{}^{237}{}_{}{}^{}\mathrm{Pu}$ [from ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}(\alpha , 2n)$], ${}_{}{}^{235}{}_{}{}^{}\mathrm{Np}$ [from ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}(d, 2n)$], ${}_{}{}^{236}{}_{}{}^{}\mathrm{Np}$ [from ${}_{}{}^{23s}{}_{}{}^{}\mathrm{U}(d, 4n)$]; measured $E_{\gamma }$, $I_{\gamma }$, $E_{\mathrm{ce}}$, $I_{\mathrm{ce}}$. ${}_{}{}^{237}{}_{}{}^{}\mathrm{Np}$, ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$, ${}_{}{}^{236}{}_{}{}^{}\mathrm{Pu}$ deduced levels, $log\mathrm{ft}$ (EC), $log\mathrm{ft}$ (${\beta }^{-}$), $\gamma$ multipolarity, $I$, $\pi$. Mass-separated ${}_{}{}^{237}{}_{}{}^{}\mathrm{Pu}$. Cooled Si(Li) electron spectrometer.

• Received 20 December 1982

DOI:https://doi.org/10.1103/PhysRevC.27.2239