A Study of the Spectrum of the Neutrons of Low Energy from the Fission ofU235

A cloud chamber has been used to determine, in the energy range 0.05 to 0.7 Mev, the distribution of prompt neutrons produced by the fissions of ${\mathrm{U}}^{235}$ in a thermal neutron beam. The ratio of proton recoils in the energy range 0.05 to 0.6 Mev to the recoils in the energy range 0.6 Mev to infinity was also determined. The data fit a distribution function $N\left(E\right)=sinh{\mathrm{}\left(2E\right)\mathrm{}}^{\frac{1}{2}}{e}^{-E}$.