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

FTK: the hardware Fast TracKer of the ATLAS experiment at CERN In the ever increasing pile-up of the Large Hadron Collider environment, the trigger systems of the experiments have to be exceedingly sophisticated and fast at the same time, in order to select the relevant physics processes against the background processes. The Fast TracKer (FTK) is a track finding implementation at hardware level that is designed to deliver full-scan tracks with $p_{T}$ above 1 GeV to the ATLAS trigger system for every L1 accept (at a maximum rate of 100kHz). To accomplish this, FTK is a highly parallel system which is currently under installation 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 to cover the whole detector. The system is based on pattern matching between hits coming from the silicon trackers of the ATLAS detector and 1 billion simulated patterns stored in specially designed ASIC chips (Associative memory – AM06). In a first stage, coarse resolution hits are matched against the patterns; subsequently, the fine resolution hits in the matched patters undergo track fitting implemented in FPGAs. Tracks above the 1GeV threshold are delivered to the High Level Trigger within about 100 μs. The resolution of the tracks coming from FTK is close to the offline tracking resolution and it will allow for reliable detection of primary and secondary vertices at trigger level and improved trigger performance for b-jets and tau leptons. This presentation will provide an overview of the FTK system architecture and its commissioning status. Moreover, its expected performance will be briefly presented.