Reconstruction of neutral mesons via photon conversion method in Ag-Ag collisions at 1.58A GeV with HADES

Abstract

The physics program of the HADES (High Acceptance DiElectron Spectrometer) experiment is focused on investigating properties of strongly interacting matter at moderate temperatures and large baryo-chemical potential. Amongst the most important observables to be studied are virtual photons and their decays into electron pairs $\left (\textrm{e}^{-} + \textrm{e}^{+} \right)$ in hadron and heavy-ion collisions. As electrons are not affected by final-state interactions, the electrons and positrons offer the possibility to look into the dense nuclear medium in the first stage of collisions. The major background in the dielectron spectrum at low invariant masses are Dalitz-decays of light neutral mesons. Hence, the precise knowledge of neutral meson production is mandatory for the dielectron analyses. In HADES, these mesons can be reconstructed via their dominant $\gamma \, \gamma$ decays utilizing double photon detection in the electromagnetic calorimeter (ECAL) or via double photon conversion $\gamma \, + \, \textrm{X} \rightarrow \textrm{e}^{+} + \textrm{e}^{-}$ in target or detector material with subsequent electron/positron identification. In this contribution, emphasis will be put on recent analysis results for $\pi^{0}$ and $\eta$-reconstruction via the double conversion method (DCM) in Ag+Ag collisions at 1.58A GeV.