Investigation of Nuclear Energy Levels in Lead

The total neutron cross section of lead was measured from 20 kev to 750 kev with an energy spread of 10 kev. Maxima were observed at 350, 525, and 720 kev, each maximum being preceded by a minimum. In the region surrounding these anomalies, measurements were carried out with a resolution of about 5 kev. An attempt was made to interpret the maxima as due to resonances corresponding to isolated levels in the compound nucleus ${\mathrm{Pb}}^{209}$. No energy levels were resolved when similar measurements were carried out for bismuth.