Abstract
| The physics program, the setup, and the performance of an experiment to measure elastic scattering of polarized protons at the Relativistic Heavy ion Collider (RHIC) are described. In the medium t range, diffractive region, with four momenta transferred 0.006<-t<1.5 (GeV/c)/sup 2/, the experiment will address one of the main, unsolved problems in particle and nuclear physics: long-range QCD and confinement. In the small t range, Coulomb Nuclear Interference (CNI) , 0.0004<-t<0.12(GeV/c)/sup 2/, the experiment will, in a model- independent way, test general analytical properties of scattering amplitudes: analyticity, unitarity, and crossing symmetry. In addition, by measuring single spin asymmetries such as A/sub N/, double spin correlation parameter A/sub NN/, and cross section difference Delta sigma gamma = sigma /sub tot/( up arrow , down arrow )- sigma /sub tot/( up arrow , up arrow ) we will be able to determine the helicity amplitudes phi /sub i/. Those amplitudes are not well known at this time, so their systematic Study at RHIC will help understand spin structure of nucleon and the exchanged mediator of the force, Pomeron and Odderon. A polarized gas jet target added to the setup will expand the physics capabilities to cover the fixed- target range of energies, giving centre of mass (cms) energy range 7< square root s<500 GeV. (8 refs). |