1. 1 DØ trigger system 3 levels L1 deadtimeless L1 deadtimeless L2 100  s L2 100  s L3 farm, 50 Hz L3 farm, 50 Hz Brown involvement L2 STT L2 STT L1CTT L1CTT L2FW:Combined objects (e, , j) L1FW: towers, tracks, correlations L1CAL L2STT Global L2 L2CFT L2PS L2Cal L1 CTT L2 Muon L1 Muon L1FPD Detector L1 TriggerL2 Trigger 7 MHz2-5 kHz CAL FPS CPS CFT SMT Muon FPD 1000 Hz L3

2. 2 L2 silicon track trigger Collaborative effort of Boston University Boston University Stony Brook Stony Brook Columbia Columbia Florida State Florida State Electronic cards: 100 motherboards 100 motherboards 250 serial link boards 250 serial link boards 70 silicon trigger cards 70 silicon trigger cards Running since 2002 Brown Responsibilities Maintenance of STC cards Maintenance of STC cards on-call expert support on-call expert support Narain Hazen Wu

3. 3 L1 track trigger essential for all physics: e, ,  (WH  l jj), input for STT track trigger rates highly sensitive to occupancy upgrade stategy: narrow track roads by using hits in individual fibers (singlets) rather than pairing adjacent fibers (doublets) narrow track roads by using hits in individual fibers (singlets) rather than pairing adjacent fibers (doublets) calorimeter-track matching with finer resolution calorimeter-track matching with finer resolution upgrade scope replaced two crates of electronics replaced two crates of electronics Running seamlessly part of the trigger since last summer. Responsibilities: On site expert support On site expert support Firmware generation Firmware generation DFEA2 card maintenance DFEA2 card maintenance Narain Pangilinan