T. Iizawa

FTK: a Fast Track Trigger for ATLAS

We describe the design and expected performance of a the Fast Tracker Trigger (FTK) system for the ATLAS detector at the Large Hadron Collider. The FTK is a highly parallel hardware system designed to operate at the Level 1 trigger output rate. It is designed to provide global tracks reconstructed in the inner detector with resolution comparable to the full offline reconstruction as input of the Level 2 trigger processing. The hardware system is based on associative memories for pattern recognition and fast FPGAs for track reconstruction. The FTK is expected to dramatically improve the performance of track based isolation and b-tagging with little to no dependencies of pile-up interactions.

ATCA-based ATLAS FTK input interface system

High luminosity conditions at the LHC pose many unique challenges for potential silicon based track trigger systems. One of the major challenges is data formatting, where hits from thousands of silicon modules must first be shared and organized into overlapping eta-phi trigger towers. Communication between nodes requires high bandwidth, low latency, and flexible real time data sharing, for which a full mesh backplane is a natural solution. A custom Advanced Telecommunications Computing Architecture data processing board is designed with the goal of creating a scalable architecture abundant in flexible, non-blocking, high bandwidth board to board communication channels while keeping the design as simple as possible. We have performed the first prototype board testing and our first attempt at designing the prototype system has proven to be successful. Leveraging the experience we gained through designing, building and testing the prototype board system we are in the final stages of laying out the next generation board, which will be used in the ATLAS Level-2 Fast TracKer as Data Formatter, as well as in the CMS Level-1 tracking trigger R&D for early technical demonstrations.The first stage of the ATLAS Fast TracKer (FTK) is an ATCA-based input interface system, where hits from the entire silicon tracker are clustered and organized into overlapping eta-phi trigger towers before being sent to the tracking engines. First, FTK Input Mezzanine cards receive hit data and perform clustering to reduce data volume. Then, the ATCA-based Data Formatter system will organize the trigger tower data, sharing data among boards over full mesh backplanes and optic fibers. The board and system level design concepts and implementation details, as well as the operation experiences from the FTK full-chain testing, will be presented.

Input Mezzanine card for the fast tracker at ATLAS

The Fast Tracker is an integral part of trigger upgrade program for the ATLAS experiment. At LHC Run 2, which started operations in June 2015 at a center of mass energy of 13 TeV, the luminosity could reach up to 2•1034 cm−2 s−1 and an average of 40-50 simultaneous proton collisions per beam crossing will be expected. The higher luminosity demands a more sophisticated trigger system with increased use of tracking information. The FTK is a highly-parallel hardware system that rapidly finds and reconstructs tracks in the ATLAS inner-detector at the triggering stage. This paper focuses on the Mezzanine Board that is input module of the entire FTK system. The functions of this board are: receive the pixel and micro-strip data from the ATLAS Silicon read-out drivers, perform clustering, and forward the data to its mother board. Mass production and quality control tests of Mezzanine Boards were completed, and staged installation and commissioning are ongoing. Details of its functionality, mass production, quality control tests, and installation are reported.