Proton-helium elastic scattering: a possible high-energy polarimeter at RHIC-BNL

We examine a suggestion to use p-He-4 elastic scattering, as an absolute po larimeter for high-energy polarized proton beams, by means of a Coulomb-Nuc lear Interference effect for the single-spin asymmetry A(N)(t), around the diffractive minimum of the differential cross section \t\ similar to 0.21 G eV2. Although this reaction has a fairly simple dynamical structure, our th eoretical uncertainties and the present experimental inaccuracy of the diff erential cross section in this t region, allows one to generate dramatic ef fects for A(N)(t), which will be discussed. (C) 1998 Elsevier Science B.V. All rights reserved.