Abstract
We report precision measurements of the Feynman x (xF) dependence, and first measurements of the transverse momentum (pT) dependence, of transverse single-spin asymmetries for the production of π0 mesons from polarized proton collisions at √s=200 GeV. The xF dependence of the results is in fair agreement with perturbative QCD model calculations that identify orbital motion of quarks and gluons within the proton as the origin of the spin effects. Results for the pT dependence at fixed xF are not consistent with these same perturbative QCD-based calculations.