π0 Double Longitudinal Helicity Asymmetry Measurements at PHENIX

Abstract

Measurement of the gluon's contribution to the proton spin, ΔG, is an important component of the RHIC spin program. One particular avenue for constraining ΔG is through the π0 double longitudinal helicity asymmetry, ALL. The large p + p → π0 cross section coupled with the high resolution of the PHENIX EM-Calorimeter make this an attractive measurement. After some discussion of the measurement, existing PHENIX π0 ALL results at center of mass energies √s = 62.4 and 200 GeV are presented, including new 200 GeV results from the RHIC run ending in 2009. Projections for future 500 GeV results are also shown.