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 accelerator for the purpose of studying precisely the charge and parity violation parameters in the B-B meson system. Triggering poses special problems since the interesting events containing B-mesons are immersed in a large background of inelastic p-p reactions. Therefore, a four-level triggering scheme (Level-0 to Level-3) has been implemented. Full event building is performed between Level-1 and Level-2. Powerful embedded processors, used in modern intelligent network interface cards, are attractive to use to handle the event-building protocol in the high-speed data-acquisition system. The implementation of an event-building algorithm developed for a specific gigabit Ethernet network interface controller is presented, and results from performance measurements are discussed.