Small-Angle Proton Scattering at 3 Bev

The differential cross section for elastic scattering of 3-Bev protons has been measured with targets of hydrogen, carbon, copper, and lead over the angular range 0.5 to 4 degrees in the laboratory coordinate system. Within our limits of error, no evidence was found of Coulomb-nuclear interference with hydrogen, while with carbon there is indication of a real component of the nuclear scattering amplitude associated with a repulsive force. It is inferred from the extrapolated nuclear scattering cross section at zero degrees that appreciable scattering results form spin dependent forces with hydrogen but not with carbon. A derived value of the rms radius for $p-p$ scattering exceeds that found in electron-proton scattering by a factor $\sqrt{2}$.