The run IIb trigger upgrade for the DO experiment

The increase in instantaneous luminosity anticipated in Run IIb of the Tevatron collider at Fermilab requires increased background rejection capabilities from the trigger system of the DO detector. A set of upgrades is under way to improve triggering at level 1 in the calorimeter and tracker, and at level 2 in the silicon track trigger and software triggers. Reductions of up to a factor of ten on the rates of high transverse momentum triggers are anticipated with the upgrades described.