γRays Following Neutron Capture inU235and the Spins ofU235Resonances

Capture and fission $\gamma$ rays from epithermal neutron irradiation of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$ have been identified. The capture $\gamma$ rays were used to construct a level diagram for ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$ and to determine the spins of the ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$ resonances. Coincidence $\gamma$-ray spectra, taken with a large $4\pi$ fission neutron detector and Ge(Li) crystal were used to identify prompt-fission $\gamma$ rays. This apparatus was also used to suppress the background of prompt-fission $\gamma$ rays in the resonance spectra and to increase the probability of seeing capture $\gamma$ rays.