Dissecting the Proton's Spin with Polarized Proton Collisions at RHIC

The Relativistic Heavy Ion Collider is the world's first polarized proton collider, providing collisions at √s = 200 GeV with increasing luminosity since 2002. We report on a program to investigate the polarization of the partons in the proton via hard partonic scattering. Results from 2005 and 2006 for inclusive jets from STAR and π0s from PHENIX are beginning to provide new significant constraints on ΔG, the first moment of the gluon helicity distribution. Future measurements at √s = 500 GeV will enable investigations of the polarization of sea quarks via W production. (author)