Driven Spin Coherent Precession at RHIC

In a circular accelerator, exciting a coherent spin precession can be used to measure the spin precession tune, which is critical for understanding spin dynamics of the polarized beam. This can be achieved by driving the polarized beam with an rf dipole at an oscillating frequency fres in the vicinity of the beam spin precession frequency fs, namely, fres≅fs. The driven coherent spin precession was measured with the RHIC Coulomb Nuclear Interference polarimeter using a carbon target. This paper presents the spin coherent precession observed with polarized proton beam at the BNL RHIC. Both experimental data and its application for spin tune measurement are discussed.