  Excitation functions A_N(p_{lab},Theta_{c.m.}) of the analyzing power in
elastic proton-proton scattering have been measured in an internal target
experiment at the Cooler Synchrotron COSY with an unpolarized proton beam and a
polarized atomic hydrogen target. Data were taken continuously during the
acceleration and deceleration for proton kinetic energies T_{lab} (momenta
p_{lab}) between 0.45 and 2.5 GeV (1.0 and 3.3 GeV/c) and scattering angles 30
deg < Theta_{c.m.} < 90 deg. The results provide excitation functions and
angular distributions of high precision and internal consistency. The data can
be used as calibration standard between 0.45 and 2.5 GeV. They have significant
impact on phase shift solutions, in particular on the spin triplet phase shifts
between 1.0 and 1.8 GeV.

Nuclear Experiment