The new inner-TEC trigger of the L3 experiment using a hadwired neural network processor

A new first-level trigger for the L3 experiment at LEP (CERN) is presented. It is using the inner time expansion chamber of the detector. The event selection is based on identifying sectors containing genuine tracks originating from the interaction point. The sector identification uses a neural network algorithm tuned to identify single tracks in a sector (hadronic jets are also selected). The hardware for this trigger is built around existing custom made neural network digital modules. The decision time is less than 100 ns and the final rate of accepted events is 1–5 Hz depending on the beam luminosity.