Energy Dependence of P P and P -carbon Cni Analyzing Power *

The method described in my RHIC Spin Note (hep-ph/305085) is applied to recently reported data from RHIC experiments in order to obtain values for the spin-flip Regge couplings. The data comes from both 100 GeV/c proton elastic scattering on a carbon target and on the recently commissioned polarized hydrogen gas jet target. These couplings are used to predict the analyzing power for proton-carbon scattering at the top RHIC fixed target energy of 250 GeV/c and for pp scattering at RHIC collider energy. The Coulomb-nuclear interference induced asymmetry in proton elastic scattering has been seen to be a very sensitive and practical polarime-ter for high energy proton beams 1,2. The main uncertainty in calculating this analyzing power is the unknown hadronic-spin flip amplitude, which we characterize by the quantity τ , the ratio of the single-flip to the non-flip proton scattering amplitude. τ cannot be calculated with the requisite precision and so it is necessary to calibrate the polarimeter. For a carbon target this is possible at AGS energy, about 24 GeV/c, where other means of determining the beam polarization are available, but it is not possible at higher energy. The goal of my RHIC Note 3 is to calculate the analyzing power at higher RHIC energy when the polarization is known at only the injection energy. This work relies heavily on earlier work 4 which shows, among other things, that it is quite reasonable to assume that τ for pC is equal to the I = 0 part of τ for pp and that its variation with t over the CNI region can be neglected. Its variation with s needs to be determined. (We will often use the beam momentum p and the proton-proton c.m. energy squared s = 2m 2 + 2m p 2 + m 2 interchangeably.) To address this, I have taken a simple model that has been successfully used for unpolarized scattering over a wide