FTK: The hardware Fast TracKer of the ATLAS experiment at CERN

In the ever increasing pile-up environment of the Large Hadron Collider, trigger systems of the experiments must use more sophisticated techniques in order to increase purity of signal physics processes with respect to background processes. The Fast TracKer (FTK) is a track finding system implemented in custom hardware that is designed to deliver full-scan tracks with pT above 1 GeV to the ATLAS trigger system for every Level-1 (L1) accept (at a maximum rate of 100 kHz). To accomplish this, FTK is a highly parallel system which is currently being installed in ATLAS. It will first provide the trigger system with tracks in the central region of the ATLAS detector, and next year it is expected that it will cover the whole detector. The system is based on pattern matching between hits coming from the silicon trackers of the ATLAS detector and one billion simulated patterns stored in specially designed ASIC Associative Memory chips. This document will provide an overview of the FTK system architecture, its design and information about its expected performance