Measurement of direct photons with a new $\pi^{0}$ tagging method in $\sqrt{s}=200Gev$ AuAu Collision at PHENIX

Direct photons provide a tool to study the different stages of a heavy ion collision, especially the formation of a quark-gluon plasma, without being influenced by the strong interaction and hadronization processes. The yield of direct photons can be determined based on the double-ratio $(\gamma_{inclusive}/\gamma(\pi^{0}))_{measured}/(\gamma_{decay}/\gamma(\pi^{0}))_{calculated}$ technique. A new method to determine the double-ratio is presented, which should lead to smaller systematic errors at low $p_{T}$. It uses strict photon identification in the EMCAL and a charged particle veto to extract a clean photon signal. The clean photons are then tagged with EMCAL photon candidates, which can be reconstructed with high efficiency, to determine the fraction of photons originating from $\pi^{0}$ decays. Many systematic uncertainties and detector effects cancel in this method. The status of this analysis and comparison with previous published results will be discussed.