Photofission of by photons populates the fissioning nucleus at an excitation of about
PHYSICS · Multi-part · Fermi University Physics · Nuclear Physics · The nuclear force and nuclear models · Fission, fusion and nuclear energy
The Nucleus Resolved, Ch Fission: the double-humped barrier and the shells the drop cannot see
Problem
Photofission of 238U by 20MeV photons populates the fissioning nucleus at an excitation of about 20MeV, some 15MeV higher than the excitation reached in thermal-neutron fission of 235U. Without calculating a barrier or a level density, predict:
((a)) whether the fragment mass-yield curve for this photofission shows two well-separated peaks with a deep valley, or a single broad hump, and why.
((b)) whether the light and heavy peaks, where still resolvable, would lie closer together than the thermal-fission peaks near A=95 and A=139, further apart, or roughly where those peaks lie, and why.