Scattering of 7.5-Mev Protons by Helium

The differential cross section for the elastic scattering of 7.5±0.1 Mev protons from helium has been measured at 2.5° intervals over the laboratory angular range 10° to 172.5° using the Los Alamos nuclear plate camera. The results obtained have an absolute standard error of ±2.5% to ±3%. A phase-shift analysis of the data gives for the $S$, $P$, and $D$ phase shifts: ${\delta }_0=-57.95\mathrm{}°$, ${{\delta }_1}^{+}=112.1\mathrm{}°$, ${{\delta }_1}^{-}=52.51\mathrm{}°$, ${{\delta }_2}^{+}=0.44\mathrm{}°$, ${{\delta }_2}^{-}=-1.87\mathrm{}°$. These results fit the experimental data with a root-mean-square deviation of 2.7% and appear to be in harmony with those determined from experiments at other energies.