Expérience sur la désintégration η

A symmetric array of electronic counters in position on the m4d beam line. This experiment, involving a CERN/ETH team, collected data on the decay of the neutral eta meson into three pions (positive, negative and neutral). It was thought that this decay might show up a possible violation of charge invariance in the strong or electromagnetic interaction and thus contribute to the intensive investigation of the CP invariance law at the time.