Ay Measurement in p→p-Elastic Scattering at Small Angles

Abstract

The proton analysing power in [Formula: see text] elastic scattering has been measured at small angles at COSY-ANKE at 796[Formula: see text]MeV and five other beam energies between 1.6 and 2.4[Formula: see text]GeV using a polarized proton beam. The asymmetries obtained by detecting the fast proton in the ANKE forward detector or the slow recoil proton in a silicon tracking telescope are completely consistent. The sources of the systematic uncertainties and the time stability issue were considered. The ANKE data at the higher energies lie well above the predictions of the most recent partial wave solution at small angles. An updated phase shift analysis that uses the ANKE results together with the World data leads to a better description of these new measurements.