Low-Lying Levels ofPb208withg92,i112, orj152Neutron-Particle Configurations

The low-lying states of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ which have a neutron configuration ($g_{\frac{9}{2}}$, $j^{-1\mathrm{}}$) are studied in proton scattering at the resonance energy for the $g_{\frac{9}{2}}(\mathrm{g}.\mathrm{s}.\mathrm{})$ single-neutron isobaric-analog resonance (IAR) in ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$. The onresonance proton angular distributions are taken from 15° to 170° for states between 3.0- and 4.5-MeV excitation in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, and are found to be nearly symmetric about 90° except for the lowest $5^{-}$ (3.192-MeV) state. Total proton inelastic scattering cross sections and proton partial widths are obtained from the angular distributions. The states in the energy ranges 3.0-3.8, 3.8-4.15, and 4.15-4.8 MeV in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ are found to have the dominant neutron-neutron-hole configurations of ($g_{\frac{9}{2}}$, ${p_{\frac{1}{2}}}^{-1\mathrm{}}$), ($g_{\frac{9}{2}}$, ${f_{\frac{5}{2}}}^{-1\mathrm{}}$), and ($g_{\frac{9}{2}}$, ${p_{\frac{3}{2}}}^{-1\mathrm{}}$), respectively. Some tentative spin assignments based on the partial widths, excitation energy, and angular distributions of the states are given. Two previously unreported states at 3.940 and 4.376 MeV in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ are observed in the high-resolution ($p$, $p^{\prime }$) spectrograph data, and the levels previously reported at 4.032 and 4.252 MeV are observed to be doublets with 12- and 6-keV energy separations, respectively. The cross sections were also measured for the ($p$, $p^{\prime }$) reaction at the $g_{\frac{9}{2}}$ resonance at 20°, 40°. 60°, and 90° for 24 states between 4.6- and 6.00-MeV excitation. In addition to the $g_{\frac{9}{2}}$ resonance, the $i_{\frac{11}{2}}$ (0.79-MeV) IAR and