Calibration of the Phenix Lead Scintillator Calorimeter

In the early summer of 2000, the PHENIX experiment for heavy-ion physics at RHIC began, and that for spin physics was started in 2001. In this experiment, the electromagnetic calorimeter (EMCal) plays an important role in detecting photons and electrons/positrons. In order to cover topics in both areas of physics, e.g., thermal photon measurements in heavy-ion physics, and prompt photon, π⁰ and weak boson measurements in spin physics, the EMCal must cover a wide energy range from a few hundred MeV to 80 GeV. Spin physics also requires the energy measurement to be within 2% accuracy for measuring cross sections of prompt photons and π⁰ production with 10% errors, because the cross sections have steep transverse momentum (p_T) slopes. The PHENIX EMCal consists of a lead scintillator (PbSc) and lead glass (PbGl). In this paper, we will report the performance of the PbSc and the achievement of 2% accuracy.