Study of Actinide Photonuclear Reactions Induced by Gamma Radiation from Neutron Capture

The photodisintegration of ²³²Th, ²³³U, ²³⁸U, ²³⁷Np, and ²³⁹Pu has been studied with monochromatic photons produced by neutron capture using the IEA-R1 reactor. The ratios σ_γf(X)/σ_γf(²³⁸U) (relative fissionability), σ_γf/σ_α (photofission branching ratio), and Γ_n/Γ_f (neutron emission and fission competition) are shown to be independent of excitation energy, within the experimental errors, in the 6.73- to 9.72-MeV energy interval. Some correlations of these ratios with Z²/A and (E′_f — B′_n) are performed, and the results are in reasonable agreement with the theoretical model predictions.