High p_t single identified particles in various collision systems with the phenix detector at rhic

Jet quenching in the hot, dense medium formed in Au + Au collisions leads to the suppression of high p_T particles which can be studied with the measurement of the leading hadrons, like π⁰ . They can be used to investigate the mechanism of energy loss of partons in a QGP when varying the collision geometry. Asymmetric Cu + Au collisions provide a system with similar energy density but different collision geometry when compared to Au+Au, with the same number of nucleon-nucleon collisions. Furthermore, at RHIC we can study different highly asymmetric collisions, such as p+Au, d+Au and ³He+Au . The observation of collective behavior in these systems suggests the creation of a medium, but alternate explanations exist. The systematic study of the π⁰ production could give us deeper understanding of the physics in these very asymmetric systems. We present new measurements of π⁰ with PHENIX in the asymmetric collisions at midrapidity η <0.35 with collision energy s_NN = 200 GeV.