A fast hardware tracker for the ATLAS trigger system

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

As the LHC luminosity is ramped up to the design level of 1034 cm-2s-1 and beyond, the high rates, multiplicities, and energies of particles seen by the detectors will pose a unique challenge. Only a tiny fraction of the produced collisions can be stored on tape and immense real-time data reduction is needed. An effective trigger system must maintain high trigger efficiencies for the physics we are most interested in, and at the same time suppress the enormous QCD backgrounds. This requires massive computing power to minimize the online execution time of complex algorithms. A multi-level trigger is an effective solution for an otherwise impossible problem. The Fast Tracker (FTK) is a proposed upgrade to the ATLAS trigger system that will operate at full Level-1 output rates and provide high quality tracks reconstructed over the entire detector by the start of processing in Level-2. FTK solves the combinatorial challenge inherent to tracking by exploiting the massive parallelism of Associative Memory (AM) that can compare inner detector hits to millions of pre-calculated patterns simultaneously. The tracking problem within matched patterns is further simplified by using pre-computed linearized fitting constants and leveraging fast DSP's in modern commercial FPGA's. Overall, FTK is able to compute the helix parameters for all tracks in an event and apply quality cuts in approximately one millisecond. By employing a pipelined architecture, FTK is able to continuously operate at Level-1 rates without deadtime. The system design is defined and studied using ATLAS full simulation. Reconstruction quality is evaluated for single muon events with zero pileup, as well as WH events at the LHC design luminosity. FTK results are compared with the tracking capability of an offline algorithm.

Original languageEnglish (US)
Title of host publication2009 IEEE Nuclear Science Symposium Conference Record, NSS/MIC 2009
Pages1876-1879
Number of pages4
DOIs
StatePublished - 2009
Externally publishedYes
Event2009 IEEE Nuclear Science Symposium Conference Record, NSS/MIC 2009 - Orlando, FL, United States
Duration: Oct 25 2009Oct 31 2009

Publication series

NameIEEE Nuclear Science Symposium Conference Record
ISSN (Print)1095-7863

Other

Other2009 IEEE Nuclear Science Symposium Conference Record, NSS/MIC 2009
CountryUnited States
CityOrlando, FL
Period10/25/0910/31/09

ASJC Scopus subject areas

  • Radiation
  • Nuclear and High Energy Physics
  • Radiology Nuclear Medicine and imaging

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