Total Cross Sections Measured with Photo-Neutrons

The total neutron cross sections of twenty-three elements have been measured by use of six photo-neutron sources ranging from 0.024 Mev to 0.83 Mev. The cross sections of the lighter elements behave very anomalously; broad resonances in the scattering are observed in F, Na, Mg, Al, and S. Nickel has the exceptionally high cross section of 23×${10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$ at 0.024 Mev. The cross sections of elements of atomic weight about 110 show very little variation with energy and are about 7×${10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$. Three heavy elements have cross sections of about 13×${10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$ at 0.024 Mev and decrease monotonically to about half that value at 0.83 Mev.