First results of the CELSIUS/WASA experiment
The CELSIUS/WASA experiment is now finishing its commissioning phase and has started regular data talcing in autumn 2001. Results from a first analysis of data samples from an experimental run at a beam energy of Tp = 1360MeV in September 2001 are presented. The results show the ability to tag π0 and η production events. For 2π0 production a large data sample exists. The 2π0 and 3π0 production processes will be important sources of background for the η decays. They have until now been poorly measured, if at all. at this energy. The decay η → γγ will be used for normalization of all other η decays and the η → 3π0 decay will test the light quark mass ratio predicted by Chiral Perturbation Theory.