High-Speed Electronics

High-Speed Electronics

High-Speed Electronics

Complex objects often slip past our data filtering systems (triggers). By constructing extremely fast, sophisticated electronics systems that specifically search for these complex structures in real-time, we can recover these otherwise lost objects. This is the gFEX boosted object trigger for Run 3 of the LHC.

Approach

  • The global feature extraction (gFEX) system is a hardware-based boosted object jet finder for the ATLAS trigger system.
  • gFEX is an official Phase I upgrade project in ATLAS and will be operational for Run 3 of the LHC, and we have already recorded pp collision data as of Oct 17, 2018!
  • By allowing for trigger decisions to be based on a large, more global region of the calorimeter, the overlap and proximity between the local energy depositions can be incorporated as part of the trigger decision.
  • This system can therefore process the entire calorimeter on a single electronics board. Dedicated trigger algorithms have been developed to reconstruct signatures of Lorentz-boosted particles such as top quarks, W/Z bosons, and even the Higgs boson.
  • New jet algorithms can then be deployed at Level-1 such as the large-radius anti-kT algorithm. Jet substructure information can also be incorporated into the selection algorithm in order to reduce the rate from light jet backgrounds while maintaining high efficiency for Lorentz-boosted massive particles.
  • In addition to jet substructure, gFEX will also implement a new pile-up suppression scheme based on an energy-density-based subtraction for jets and missing transverse energy. As the instantaneous luminosity increases, this subtraction scheme allows for calorimeter-based jet thresholds to remain constant.