Inclusive $\pi^0$ Production in Longitudinally Polarized pp Collisions at $\sqrt{s}$=200 GeV Using the STAR Endcap Electromagnetic Calorimeter

Measurement of the double-spin asymmetry $A_{LL}$ for inclusive $\pi^0$ production in polarized pp collisions can provide important constraints on gluonic contributions to the proton's spin.$^1$ The STAR Endcap Electromagnetic Calorimeter (EEMC) is well suited for these studies, providing full azimuthal coverage for $1.086 \leq \eta \leq 2$, and with separate readout of two pre- and one post-shower layers, and a fine grain scintillator-based shower maximum detector (SMD) that can distinguish between single photons or electrons, charged hadrons, and neutral mesons ($\pi^0$'s and $\eta$'s) via the observed transverse shower profile. The EEMC also provides fast triggering on significant energy deposition in individual towers, trigger patches, or jet patches ($\Delta\eta \times \Delta\phi \approx 0.007, 0.06, 1$, respectively). Details of the $\pi^0$ reconstruction algorithm employed, and the current status of analysis of the 2006 longitudinally polarized pp data set (sampled luminosity $\approx$~3.5~pb$^{-1} $) will be presented. \break $^1$ B.~Jager, M.~Stratmann and W.~Vogelsang, Phys.\ Rev.\ D {\bf 70}, 034010 (2004) [arXiv:hep-ph/0404057].