Small-angle p − p elastic scattering at energies between 285 and 572 MeV

Differential cross sections for elastic $p\ensuremath{-}p$ scattering have been measured at 285, 348, 398, 414, 455, 497, 530, and 572 MeV kinetic energy. The experiment was performed at the CERN synchrocyclotron, using multiwire proportional chambers placed directly in a proton beam. Scattering was observed for $1.5\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\lesssim}\ensuremath{\theta}\ensuremath{\lesssim}10\ifmmode^\circ\else\textdegree\fi{}$ in the laboratory system. The ratio ${\ensuremath{\alpha}}_{p}$ of the real and imaginary parts of the non-spin-flip nuclear forward amplitude was derived from the interference between the Coulomb and nuclear amplitudes. The values obtained are model-dependent, but in this energy range ${\ensuremath{\alpha}}_{p}$ is positive and decreases with energy. Qualitatively good agreement with dispersion-relation predictions is observed.