Jet reconstruction in the DØ experiment trigger system

The DO experiment at Fermilab records the results of high energy collisions between protons and antiprotons. These high energy particle collisions often result in the production of collimated jets of secondary particles. The trigger system selects, in real time, collision events to be analysed via a detailed reconstruction. A fast reconstruction and identification of particle jets and other physics objects is done in the trigger system in the event selection process. Two possible improvements to the jet reconstruction software algorithm for the trigger system were implemented. The improvement that emulates the offline reconstruction software was found to yield a jet trigger rate reduction of up to 14% without reducing the trigger system performance. As such, it is favored for use in the online trigger system. The performance of the trigger system at reconstructing jets is measured from data. Biases of the measurement methods are identified and quantified. Measured efficiencies are then used to emulate the online trigger response in simulated events