A charged particle trigger based on neural networks for the L3 experiment using the inner-TEC detector

A new first-level trigger for the L3 experiment at LEP (CERN) is presented. It uses the inner time expansion chamber of the detector, which is not until now used for triggering. The event selection presented here is based on identifying sectors containing genuine tracks originating from the interaction point. The system is capable of identifying both single tracks and hadronic jets in a sector. The sector identification used a neural network algorithm. The hardware for the event selection is built around the existing custom-made neural network digital modules. Events are classified in less than 100 ns and the final rate of accepted events is 1–3 Hz starting from a beam-crossing rate of 45 kHz.