Design and implementation of the level 1 charged particle trigger for the BABAR detector

The environment of the high-luminosity PEP-II machine poses unique design c hallenges for the trigger system of the BABAR detector. These led to the ad option of a real-time parallel pipelined architecture for the trigger elect ronics which departs significantly from previous implementations at convent ional e(+)e(-) experiments. One challenge for the trigger designer lies in detecting low multiplicity physics events with high efficiency while keepin g the background rate within the data acquisition limits. To achieve this d ifficult task, creative and innovative high-speed trigger algorithms were d esigned, simulated and implemented in Field Programmable Gate Arrays, using advanced CAD/CAE tools. The simulation results indicate that these algorit hms will be able to perform all required tasks quickly and efficiently. Thi s paper describes the design of the Level 1 Drift Chamber Trigger System of the BABAR detector, including the trigger algorithms, design and test meth odology of the implementation, as well as test and simulation results.