| The division of the proton's spin among its quarks and gluons is a fundamental question in modern nuclear physics. The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) is measuring asymmetries in polarized proton-proton collisions at s = 200 GeV to garner information about the polarizations of the quarks and gluons. Measurements of the double helicity asymmetry for high pT mid-rapidity eta meson production in proton-proton collisions at s = 200 GeV are presented in this work.;In order to obtain information about the polarizations of the quarks and gluons in the proton using the eta meson, the eta meson fragmentation functions must be known. No set existed, therefore a first global fit to the eta meson fragmentation functions was performed. The fit benefits from the inclusion of measurements of the cross section for eta meson production in proton-proton collisions. Therefore, a measurement of the cross section for high pT mid-rapidity eta meson production in proton-proton collisions at s = 200 GeV is performed to aid the fit.;With the eta fragmentation functions, the measurement of the double helicity asymmetry is used to constrain the contribution of the spins of the gluons to the spin of the proton. Using a model and the work in this thesis, an estimate of the gluon contribution to the proton's spin is calculated and compared to other evaluations. |
