Double longitudinal spin asymmetry in neutral pion production in polarized p+p collisions at √s=200 GeV at PHENIX

A major goal of the RHIC spin program is to measure Delta g, the gluon contribution to the proton's spin. Measurements by PHENIX of the double longitudinal spin asymmetry, ALL, of the neutral pion production at mid-rapidity in polarized proton collisions have been shown to constrain Delta g. Results from the 2005 RHIC run, as well as high PT data from the 2006 RHIC run, are presented. The results disfavor maximal positive and negative values of Delta g. A measurement of azimuthally independent double transverse spin asymmetry, A(TT), is also presented.