Abstract
In 2015 the Large Hadron Collider will run with increased center-of-mass energy and luminosity. To maintain a high efficiency in selecting interesting collisions for the physics analyses in the next data-taking period, event topology information will be added to the ATLAS Level-1 real time data path and processed by a new Topology Processor (L1Topo). To cope with the luminosity levels foreseen after the 2018 LHC upgrade, a new digital trigger path for the Liquid Argon calorimeters will provide finer granularity and depth segmentation in the electromagnetic layer to new Level-1 feature extractors (FEX) for an improved electron, photon, tau and jet selection. We present the ongoing and future calorimeter trigger upgrades to the ATLAS Level-1 trigger.
Highlights
Level-1 real time data path and processed by a new Topology Processor (L1Topo)
Upon an L1A, the jet-energy sum modules (JEM) and CPM modules read out the coordinates and thresholds passed by each identified candidate to the high-level trigger as Regions of Interest (RoIs)
For the second long shutdown in 2018 (LS2), new on-detector electronics will be installed for the Liquid Argon Calorimeter to provide a new trigger path of all calorimeter samples, allowing higher-granularity calorimeter information to be sent to L1Calo
Summary
Several upgrades to the current L1Calo system are already underway during the 201314 long shutdown (LS1). The first, not covered in this paper, is an FPGA-based replacement for the front-end multichip module (MCM) for the L1Calo PreProcessor that will provide improved noise performance and more sophisticated digital filtering at higher pileup conditions. Upgrades to the digital algorithm processors will add topology information to the realtime data path. Modules capable of receiving the higher-speed backplane data and performing local multiplicity processing with more thresholds, as well as sending the TOBs over high-speed optical links to a new topological processor subsystem (L1Topo) subsystem. For the second long shutdown in 2018 (LS2), new on-detector electronics will be installed for the Liquid Argon Calorimeter to provide a new trigger path of all calorimeter samples, allowing higher-granularity calorimeter information to be sent to L1Calo. The new offdetector digital processing chain will consist of a so-called Digital Processor System (DPS) that will perform digital filtering on the new digital calorimeter data, and two new L1Calo “feature extractor” subsystems, one for improved electron/hadron identification (eFEX) and one for jet identification (jFEX)
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