Design and implementation of the new DO level-1 calorimeter trigger

Increasing luminosity at the Fermilab Tevatron collider has led the DO collaboration to make improvements to its detector beyond those already in place for Run IIa, which began in March 2001. One of the cornerstones of this Run IIb upgrade is a completely redesigned level-1 calorimeter trigger system. The new system employs novel architecture and algorithms to retain high efficiency for interesting events while substantially increasing rejection of background. We describe the design and implementation of the new level-1 calorimeter trigger hardware and discuss its performance during Run lIb data taking. In addition to strengthening the physics capabilities of DO, this trigger system will provide valuable insight into the operation of analogous devices to be used at LHC experiments.