High-energy gamma rays from spontaneous fission of $sup 238$U

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