The fast track real time processor and its impact on muon isolation, tau and b-jet online selections at ATLAS

A. Andreani*, A. Andreazza, A. Annovi, M. Beretta, V. Bevacqua, M. Bogdan, E. Bossini, A. Boveia, F. Canelli, Y. Cheng, M. Citterio, F. Crescioli, M. Dell'Orso, G. Drake, M. Dunford, J. F. Genat, P. Giannetti, F. Giorgi, J. Hoff, A. KapliyM. Kasten, Y. K. Kim, N. Kimura, A. Lanza, V. Liberali, T. Liu, A. McCarn, C. Melachrinos, C. Meroni, A. Negri, M. Neubauer, M. Piendibene, J. Proudfoot, G. Punzi, M. Riva, F. Sabatini, I. Sacco, L. Sartori, M. Shochet, A. Stabile, F. Tang, A. Todri, R. Tripiccione, J. Tuggle, V. Vercesi, M. Villa, R. A. Vitullo, G. Volpi, J. Wu, K. Yorita, J. Zhang

*Corresponding author for this work

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

8 Citations (Scopus)


As the LHC luminosity is ramped up to 3×1034 cm -2 s-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 current 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 massive parallelism of associative memories 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 DSPs in modern commercial FPGAs. Overall, FTK is able to compute the helix parameters for all tracks in an event and apply quality cuts in less than 100 μs. The system design is defined and studied with respect to high transverse momentum (high-PT) Level-2 objects: b-jets, tau-jets, and isolated leptons. We test FTK algorithms using ATLAS full simulation with WH events up to 3×1034 cm-2 s-1 luminosity and comparing FTK results with the offline tracking capability. We present the architecture and the reconstruction performances for the mentioned high-PT Level-2 objects.

Original languageEnglish
Title of host publicationConference Record - 2010 17th IEEE-NPSS Real Time Conference, RT10
Publication statusPublished - 2010
Event2010 17th IEEE-NPSS Real Time Conference, RT10 - Lisbon, Portugal
Duration: 2010 May 242010 May 28

Publication series

NameConference Record - 2010 17th IEEE-NPSS Real Time Conference, RT10


Conference2010 17th IEEE-NPSS Real Time Conference, RT10

ASJC Scopus subject areas

  • Artificial Intelligence
  • Computer Science Applications


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