The excited levels of ${}_{}{}^{249}{}_{}{}^{}\mathrm{Cm}$ have been determined by use of neutron-capture gamma-ray spectroscopy. Gamma-ray measurements were made with curved-crystal spectrometers of focal lengths 5.8 and 24 m and a pair spectrometer. These experimental data represent the first measurement of gamma transitions depopulating the levels of ${}_{}{}^{249}{}_{}{}^{}\mathrm{Cm}$. We present evidence for the population of 23 levels in ${}_{}{}^{249}{}_{}{}^{}\mathrm{Cm}$ up to 1300-keV excitation. The following new configuration assignments were made (listed with the corresponding bandhead energies): ${\frac{5}{2}}^{+}\mathrm{}\left[622\right]\mathrm{}$, 529.58 keV; ${\frac{3}{2}}^{-}\mathrm{}\left[752\right]\mathrm{}$, 772.74 keV; ${\mathrm{½}}^{-}$[501], 917.49 keV. Comparison of the experimentally determined level structure with theoretical calculations shows best agreement with calculations by Soloviev's group where a Woods-Saxon potential form was used and quasiparticle-phonon coupling was included. The neutron binding energy was determined to be 4713.7 ± 0.3 keV.

NUCLEAR REACTIONS ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$($n$,$\gamma$), $E=\mathrm{thermal}$; measured $E_{\gamma }$, $I_{\gamma }$, ${}_{}{}^{249}{}_{}{}^{}\mathrm{Cm}$ deduced levels, $J$, $\pi$, Nilsson assignments.

• Received 20 July 1981

DOI:https://doi.org/10.1103/PhysRevC.25.2232