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 challenges for the trigger system of the BaBar detector. These led to the adoption of a real-time parallel pipelined architecture for the trigger electronics which departs significantly from previous implementations at conventional e⁺e^- experiments. One challenge for the trigger designer lies in detecting low multiplicity physics events with high efficiency while keeping the background rate within the data acquisition limits. To achieve this difficult task, creative and innovative high-speed trigger algorithms were designed, simulated and implemented in Field Programmable Gate Arrays on printed circuit boards, using advanced CAD/CAE tools. The simulation results indicate that these algorithms will be able to perform all required tasks quickly and efficiently. This paper describes the design of the Level 1 Drift Chamber Trigger System of the BaBar detector, including the trigger algorithms, design and test methodology of the implementation, as well as test and simulation results.