First-level charged particle trigger for the L3 detector

A first-level charged particle trigger based on parallel processing and look-up tables has been developed for the L3 detector. It processes analog signals generated by the central tracking detector, a drift chamber with axial wires. The trigger decision is made on the total number of tracks, the number of coplanar pairs of tracks, or on more complicated topologies found in the projection normal to the beam axis. The system is very flexible and can be adjusted to a wide range of background conditions and tracking chamber efficiencies. (orig.)