A first level tracking trigger for the upgraded DØ detector

A fast tracking trigger system based on a new scintillating fiber tracker is being built for the upgraded DØ detector for the Collider Run II at Fermilab. This fiber tracker trigger provides a first level hardware trigger, supplies track seeds for the first level muon trigger and for the second level trigger. The physics requirements and the corresponding algorithms for the hardware trigger will be described. Particularly, PLD (programmable logical device) chips are used to implement our trigger algorithms to achieve pattern recognition from scintillating fiber hits and to format that information for delivery to other trigger systems. Detector trigger efficiency studies will also be presented