The results of photographic measurements of the neutron spectrum from the scattering at 90° of 4.4-Mev neutrons by iron have been combined with measurements of the energies of de-excitation gamma rays from the same process, as reported in the preceding paper, to give values for the energy levels excited in ${\mathrm{Fe}}^{56}$. The ${\left(\frac{d\sigma }{d\Omega }\right)}_{90°}$ for the various processes have been estimated from the areas under the peaks in the histogram. The energy levels and corresponding ${\left(\frac{d\sigma }{d\Omega }\right)}_{90°}$ for ${\mathrm{Fe}}^{56}$ are: elastic 0.076±0.02 barn/sterad; inelastic 0.85±0.02 Mev, 0.036±0.010 barn/sterad; 2.05±0.036 Mev, 0.021±0.007 barn/sterad; 2.58±0.054 Mev, 0.012±0.006 barn/sterad, 2.90 Mev. 0.020±0.013 barn/sterad. Similar measurements on carbon resulted in a ${\left(\frac{d\sigma }{d\Omega }\right)}_{90°}$ for the elastic process of 0.061±0.016 barn/sterad.

• Received 20 December 1954

DOI:https://doi.org/10.1103/PhysRev.98.582