$\eta$ meson reconstruction in pp reactions at 2.2 GeV with HADES
  The HADES spectrometer installed at GSI Darmstadt is devoted to study the production of di-electron pairs from proton, pion and nucleus induced reactions at 1-2 AGeV. In pp collisions at 2.2 GeV we have focused mainly on exclusive reconstruction of the $\eta$ meson decays in the hadronic ($\eta\to\pi^{+}\pi^{-}\pi^{0}$) and the electromagnetic channels ($\eta\to e^{+}e^{-}\gamma$). We present analysis techniques and discuss first results on $\eta$ production, with the main focus on comparisons of reconstructed distributions to results obtained by other experiments and theoretical predictions. 
S. Spataro (for the HADES Collaboration)