Enhancement of the ATLAS trigger system with a hardware tracker finder FTK RID E-5642-2011

The existing three-level ATLAS trigger system is deployed to reduce the event rate from the bunch crossing rate of 40 MHz to similar to 200 Hz for permanent storage at the LHC design luminosity of 10(34) cm(-2) s(-1). When the LHC exceeds the design luminosity, the load on the Level-2 trigger system will significantly increase due both to the need for more sophisticated algorithms to suppress background and the larger event sizes. The Fast Tracker is a proposed upgrade to the current ATLAS trigger system that will operate at the full Level-1 accepted rate of 100 kHz and provide high quality tracks at the beginning of processing in the Level-2 trigger, by performing track reconstruction in hardware with massive parallelism of associative memories. The concept design is being advanced and justified with the performance in important physics areas, b-tagging, tau-tagging and lepton isolation. The prototyping with current technology is underway and R&D with new technologies has been started.