Time Evolution of Heavy-Ion-Induced Fission Studied by Crystal Blocking

The shapes of crystal-blocking angular distributions have been used to study the fission decay of excited compound nuclei produced by bombardment of tungsten with ¹⁶O ions. The results show that while most of the fission decays ({~}80%) occur with lifetimes too short to be measured by the blocking technique (τ10^-18 sec), a large fraction ({~}20%) corresponds to lifetimes τ10^-16 sec. This indicates a significant contribution from fission after evaporation of several neutrons.