Anomalous Inelastic Scattering of 23-Mev Protons by Heavy Elements

Measurements of energy distributions from inelastic scattering of 23-Mev protons by heavy elements indicate the presence of very strong, apparently monoenergetic groups. The energies, cross sections, and angular distributions of these proton groups vary slowly and regularly with atomic number. For $Z>\mathrm{}40\mathrm{}$, there is little difference between even and odd elements, or across closed shells; this complicates any explanation of these levels by single-particle excitation, and this and other factors make collective-motion explanations difficult.