Differential Scattering of Neutrons fromPb208at Resonant Energies

Measurements are reported on differential elastic scattering of neutrons of a few keV energy spread from 99.75% ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ in the energy region 0.715 to 1.761 MeV. The results include absolute differential cross sections at 20 resonant and 9 nonresonant energies. A least-squares phase-shift analysis provides the resonance parameters and reduced widths of 21 resonances. The observed $s_{\frac{1}{2}}$ potential-scattering phase shifts are in agreement with those expected from a type of phenomenological potential which reproduces the single-particle bound states of ${}_{}{}^{209}{}_{}{}^{}\mathrm{Pb}$. Parity assignments and widths of the $J=\frac{1}{2}$ resonances are in disagreement with the prediction for 5 intermediate states arising from two-particle one-hole neutron excitations. There are, however, a number of resonances with widths corresponding to several percent of the single-particle limits which are likely candidates for some sort of intermediate states.