Inelastic Scattering of Fast Neutrons by Fe, Pb, and Bi

Measurements of inelastic scattering effects of $\mathrm{Ra}-\alpha -\mathrm{Be}$ and $\mathrm{Ra}-\alpha -\mathrm{B}$ neutrons in Fe, Pb, and Bi have been made. A ${\mathrm{U}}^{238}$ fission threshold detector was used. The method consisted in measuring the fission counting rate in the detector with and without the spherical scatterer surrounding the source. From the decrease in the counting rate caused by the presence of the scatterer, values of the cross section for inelastic scattering to below the ${\mathrm{U}}^{238}$ fission threshold were calculated for several assumed values of the elastic scattering cross section.