Event building in an intelligent network interface card for the LHCb DAQ system

LHCb is an experiment being constructed at CERN's large hadron collider acc elerator for the purpose of studying precisely the charge and parity violat ion parameters in the B-B meson system. Triggering poses special problems s ince the interesting events containing B-mesons are immersed in a large bac kground of inelastic p-p reactions. Therefore, a four-level triggering sche me (Level-0 to Level-3) has been implemented. Full event building is perfor med between Level-1 and Level-2. Powerful embedded processors, used in mode rn intelligent network interface cards, are attractive to use to handle the event-building protocol in the high-speed data-acquisition system. The imp lementation of an event-building algorithm developed for a specific gigabit Ethernet network interface controller is presented, and results from perfo rmance measurements are discussed.