The ATLAS Fast TracKer

The Fast Tracker (FTK) is a highly parallel processor dedicated to quickly and efficiently reconstructing tracks in the pixel and SCT detectors of the ATLAS experiment at LHC. It is designed to identify charged particle tracks with transverse momentum above 1 GeV and reconstruct their parameters at an event rate of up to 100kHz. The average latency of the processing is below 100 microseconds at the expected collision intensities. This performance is achieved by using custom ASIC chips with associative memory for pattern matching, while modern FPGAs calculate the track parameters. In this article is described the architecture of the FTK system, the testing and commissioning of the Associative Memory Boards (AMB) and a High-Level Data Quality Monitoring framework. This monitoring framework provides an online comparison of the FTK hardware outputs with FTK functional simulation, which is run on the pixel and SCT detector data at a low rate, allowing the detection of non-expected outputs of the FTK system.