A binary link tracker for the BABAR level 1 trigger system

The BABAR detector at PEP-II will operate in a high-luminosity e ⁺e^- collider environment near the ϒ(4S) resonance with the primary goal of studying CP violation in the B meson system. In this environment, typical physics events of interest involve multiple charged particles. These events are identified by counting these tracks in a fast first level (level 1) trigger system, by reconstructing the tracks in “real time”. For this purpose, a binary link tracker module (BLTM) was designed and fabricated for the BABAR level 1 drift chamber trigger system. The BLTM is responsible for linking track segments, constructed by the track segment finder modules (TSFM), into complete tracks. A single BLTM module processes a 360 MBytes/s stream of segment hit data, corresponding to information from the entire drift chamber, and implements a fast and robust algorithm that tolerates high hit occupancies as well as local inefficiencies of the drift chamber