Testing and Validation of the Topological Clustering Algorithm for the ATLAS Global Trigger

ATLAS is expected to receive 10 times the integrated luminosity from the High-Luminosity Large Hadron Collider (HL-LHC) than the previous three LHC runs combined, with approximately 200 interactions per bunch crossing, leading to significant pileup. The HL-LHC Trigger and Data Acquisition system is undergoing significant upgrades to manage this pileup increase. As a part of these upgrades, the planned Global Trigger system will implement offline-inspired algorithms on full-granularity calorimeter information at 40 MHz. One such algorithm reconstructs noise-suppressed topological clusters, or topoclusters, that are used as the basis for jet and tau reconstruction. Versions of this algorithm are being developed in firmware, and simulations of calorimeter cell energies have been used to validate its performance. This presentation will focus on progress regarding testing and validation of topoclustering algorithm firmware and software with realistic simulations with a mean pileup rate of 200 interactions. A first look at the effects of data quality on the topocluster algorithm performance will be shown.