Electric dipole transitions from neutron capture in 173Yb resonances

Primary neutron capture γ rays have been studied from 49 neutron resonances in 173Yb in the 10--530 eV energy range. These resonances are assigned J = 2 and J = 3 on the basis of the intensity ratios of suitable pairs of low-energy γ rays. The measured intensities of the high-energy primary γ rays have been converted to partial radiation widths. These widths have been subjected to a correlation analysis against reduced neutron widths, with the result that convincing evidence was not found for previously reported nonstatistical behavior in this nucleus. The ratio of the average population of a particular low-lying level from J = 3 resonances to its population from J = 2 resonances was found to be in satisfactory agreement with a cascade model. Resonances in the 10--200 eV range were noted to exhibit an enhancement of E1 transition probabilities to K = 2 final states as compared to K = 0 states. A level scheme for 174Yb was constructed, and the neutron separation energy for this nucleus was deduced as 7464.5 +- 1.0 keV