Constraining the Gluon Contribution to the Proton's Spin by Measuring the Double Longitudinal Spin Asymmetry in Neutral Pion Production in Polarized p+p Collisions

The quark contribution to the proton's spin measured with polarized DIS fixed target experiments was found to be only 20-30 \%. This has raised interest in measuring the gluon contribution, $\Delta g$, directly. Using the PHENIX Detector at the Relativistic Heavy Ion Collider (RHIC), we study longitudinally polarized proton collisions. The double longitudinal spin asymmetry in $\pi^{0}$ production, $A_{LL}^ {\pi^{0}}$, is related to $\Delta g$. RHIC has recently completed its second long polarized proton run. In 2005, 46\% average polarization and 2.7 pb$^{-1}$ integrated luminosity was achieved while in 2006, 60\% average polarization and 7.5 pb$^{- 1}$ was achieved. The current status of our analysis of $A_{LL}^ {\pi^{0}}$ will be presented.