Recent Mid-Rapidity ALLπ0 Measurements in Longitudinally Polarized Proton-Proton Collision at s = 510 GeV with PHENIX Experiment

It is one of the important purposes of relativistic heavy ion collider (RHIC) longitudinally polarized proton program to constrain the gluon helicity distribution ([Formula: see text]) to the proton by measuring the double helicity asymmetries ([Formula: see text]) via various probes such as [Formula: see text] ([Formula: see text]). The measurement at center of mass energy, [Formula: see text] GeV has been successfully finished and published. To explore lower x region, where dominant uncertainty remains, new measurements were carried out at an increased [Formula: see text] GeV. At this increased energy central [Formula: see text] measurements can reach a lower x range of [Formula: see text], while the previous can reach x range, [Formula: see text]. Also the statistical precision at the same transverse momentum ([Formula: see text]) is substantially improved due to accumulating about 10 times as much luminosity. Preliminary results of [Formula: see text] are presented. Larger asymmetry is observed at [Formula: see text] GeV than at [Formula: see text] GeV at the same [Formula: see text] which is expected due to evolution.