The analyzing power for proton-carbon elastic scattering in the
coulomb-nuclear interference region of momentum transfer,
9.0×10−3<−t<4.1×10−2 (GeV/c)2, was measured with a 21.7
GeV/c polarized proton beam at the Alternating Gradient Synchrotron of
Brookhaven National Laboratory. The ratio of hadronic spin-flip to non-flip
amplitude, r5, was obtained from the analyzing power to be Rer5=0.088±0.058 and Imr5=−0.161±0.226.Comment: 4 pages, 4 figures and 1 table. Accepted by Physical Review Letter