Experiment E950 at AGS, BNL has provided data with high statistics for the
left-right asymmetry of proton-carbon elastic scattering in the Coulomb-nuclear
interference region of momentum transfer. It allows to access information about
spin properties of the Pomeron and has practical implications for polarimetry
at high energies. Relying on Regge factorization the results for the parameter
r_5, ratio of spin-flip to non-flip amplitudes, is compared with the same
parameter measured earlier in pion-proton elastic and charge exchange
scattering. While data for Im r_5 agree (within large systematic errors), there
might be a problem for Re r_5. The \pi N data indicate at a rather small
contribution of the f-Reggeon to the spin-flip part of the iso-scalar amplitude
which is dominated by the Pomeron. This conclusion is supported by direct
analysis of data for elastic and charge exchange pp and pn scattering which
also indicate at a vanishing real part of the hadronic spin-flip amplitude at
energies 20 GeV and higher. This is a good news for polarimetry, since the E950
results enhanced by forthcoming new measurements at AGS can be safely used for
polarimetry at RHIC at higher energies.Comment: 11 pages. Prenary talk at 15th International Spin Physics Symposium
"SPIN 2002", Brookhaven National Laborator
