Spin dependence inppscattering in the Coulomb-nuclear interference region

The analyzing power ${\mathit{A}}_{\mathit{y}}$(θ) for pp elastic scattering at 185.4 MeV has been measured with a new technique in which the polarized beam in a storage ring was scattered from an internal ${\mathrm{H}}_2$ gas target. The measurement covered the angular range ${\mathrm{\theta }}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$=5.45°–21.36°, where ${\mathit{A}}_{\mathit{y}}$ is dominated by interference between Coulomb and nuclear amplitudes. It is found that electromagnetic spin-orbit effects are required to explain the data. The present measurement demonstrates for the first time the feasibility and the advantages of nuclear physics experiments with polarized beams in storage rings.