Commissioning experience with the ATLAS Level-1 Calorimeter Trigger system

David Charlton, Stephen Hillier, Richard Staley, Jurgen Thomas, Peter Watkins, Alan Watson

Research output: Contribution to journalArticle

2 Citations (Scopus)


The ATLAS Level-1 Calorimeter Trigger is one of the main elements of the first stage of event selection for the ATLAS experiment at the LHC. The input stage consists of a mixed analogue/ digital component taking trigger sums from the ATLAS calorimeters. The trigger logic is performed in a digital, pipelined system with several stages of processing, largely based on FPGAs, which perform programmable algorithms in parallel with a fixed latency to process about 300 Gbyte/s of input data. The real-time output consists of counts of different types of physics objects and energy sums. The production of final modules started in 2006, and installation of these modules and the necessary infrastructure at ATLAS has been underway for some time, with the intention of having a full system in situ during 2007, before first collisions at the LHC. The first experiences of commissioning and running the full scale system will be presented, along with results from integration tests performed with the upstream calorimeters, and the downstream trigger and data flow systems.
Original languageEnglish
Pages (from-to)99-105
Number of pages7
JournalIEEE Transactions on Nuclear Science
Issue number1
Publication statusPublished - 1 Jan 2008


  • pipeline processing
  • parallel architectures
  • triggering
  • real time systems


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