Instrumentation of a Level-1 Track Trigger at ATLAS with Double Buffer Front-End Architecture

The increased collision rate and pile-up produced at the HLLHC requires a substantial upgrade of the ATLAS level-1 trigger in order to maintain a broad physics reach. We show that tracking information can be used to control trigger rates, and describe a proposal for how this information can be extracted within a two-stage level-1 trigger design that has become the baseline for the HLLHC upgrade. We demonstrate that, in terms of the communication between the external processing and the tracking detector frontends, a hardware solution is possible that fits within the latency constraints of level-1.