Study of the 7.285-MeV Level in Lead-208 Using a Rotor Technique

The 7.285-MeV level in ${\mathrm{Pb}}^{208}$, excited by thermal neutron capture gamma rays from iron, was studied using a rotating target to vary the energy of the gamma rays seen by the target. Energy shifts of -1.07, -1.75, +1.65, and +2.57 eV were achieved, and the observed changes in scattered intensity are consistent with the resonant ${\mathrm{Pb}}^{208}$ level lying 6.5±1 eV below the iron capture gamma-ray line.