The Scattering of 31.5-Mev Protons from Several Elements

The elastic and inelastic scattering of 31.5-Mev protons from the Berkeley linear accelerator from Be, C, Al, Pb, and Pt have been observed, using a sodium iodide (Tl) crystal and photomultiplier for particle detection and energy measurement. Inelastic scattering led to the excitation of states or closely spaced groups of states at 2.5, 6.8 and 11.6 Mev in beryllium; 4.3, (7.5), and 9.5 in carbon; and a group of states between 11 and 17 in carbon. Deuterons have been observed from the reaction ${\mathrm{C}}^{12}\mathrm{}(p,d)\mathrm{}{\mathrm{C}}^{11}$, leading to the ground state of ${\mathrm{C}}^{11}$. Differential cross sections have been measured for all these reactions at two or three angles. The differential cross sections for the elastic scattering of 31.5-Mev protons have been measured at several angles for ${\mathrm{Be}}^9$, ${\mathrm{C}}^{12}$, ${\mathrm{Al}}^{27}$, and Pb. A comparison with the results of calculations based on several different nuclear models is made. The extreme sensitivity of the calculated cross sections (in the backward hemisphere) to the individual phase shifts and amplitudes indicates that moderately rough measurements of the backward scattering cross sections of nuclei for neutrons in this energy range would give accurate determinations of the individual phase shifts.