Energy levels of Cm249 from measurements of thermal neutron capture gamma rays

The excited levels of Cm249 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 Cm249. We present evidence for the population of 23 levels in Cm249 up to 1300-keV excitation. The following new configuration assignments were made (listed with the corresponding bandhead energies): 52+[622], 529.58 keV; 32-[752], 772.74 keV; 1/2-[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 Cm248(n,), E=thermal; measured E, I, Cm249 deduced levels, J, , Nilsson assignments.