High-Energy Gamma Rays from Spontaneous Fission ofU238

A large shielded liquid-scintillation detector operating 3240 m below the surface of the earth was used to detect $\gamma$ rays from the spontaneous fission of a ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ source. In an energy range from 8 to 20 MeV, the derived spectrum is: $N\left(E\right)=(6.99\mathrm{}\pm 0.60)\times {10}^{-1\mathrm{}}{e}^{-\frac{E}{1.41\pm 0.12}}$ photons ${\mathrm{fission}}^{-1\mathrm{}}$ Me${\mathrm{V}}^{-1\mathrm{}}$.