PHENIX measurement of high p_T particles in Au+Au and d+Au collisions at sqrt{s_{NN}} = 200 GeV

We present new results on the production of charged hadrons and neutral pions in Au+Au and d+Au collisions at roots(NN) = 200 GeV, measured within the PHENIX experiment. We observe the opposite centrality dependence when comparing the two collision systems: an increase with centrality compared to the binary scaled yield from p+p collisions in d+Au and a decrease with centrality in Au+Au.