L1 Trigger

Overview of the group activities

The main focus of CMG Level-1 trigger efforts is related to the Phase-2 upgrade of the L1 Trigger, and especially of the Corrrelator Trigger, the central piece of the upgraded trigger architecture where information from the tracker, muon and calorimeter subdetectors is combined to run particle flow and e/γ object reconstruction and build high-level physics objects (jets, MET, tau).

CMG activities on the Correlator range from algorithm development and physics performance studies with simulation to the implementation of algorithms into firmware, to the integration of algorithms into demonstrator systems and testing on prototype hardware.

Some work on the Phase-2 upgrade is done in collaboration with the CERN EP-CMD group, which is leading the development of the Global Trigger and L1 Data Scouting systems, and maintains a lab in building 40 where the CERN-owned hardware prototypes are installed.

The group is among the main contributors to the development of tools to port MVA discriminators (DNNs, BDTs) to FPGA firmware using the hls4ml and conifer libraries (also beyond CMS).

An additional activity in the group is the development of anomaly detection in the level-1 trigger for Run 3.

Phase-2 L1T upgrade: references and practical information

• References: L1 Trigger Upgrade TDR (PDF from CDS), Correlator Twikipage
• Communication channels: egroups: cmg-L1triggerStudies (CMG) and cms-trigger-p2l1pfp (CMS-wide), hypernews: L1 Trigger, L1 Trigger upgrades
• Meetings:
  • CMG L1T Upgrade chat, Wednesday 11:00, weekly, announced on cmg-L1TriggerStudies e-group
  • CMS meetings: the Correlator meeting time slot is Thursday 17:00, irregularly scheduled, announced on hn-cms-l1trigger hypernews
• Overview of the Correlator Firmware, with link to repositories, and recipes to install Vivado
• Recipes for test boards
• CMSSW: Correlator branches & recipe, L1T upgrade central twiki
• Tutorials: HLS, HLS4ML, Serenity

Phase-2 L1T upgrade: Fellow & student projects

Here below is the list of all the Fellows and students working on the project, and their current and past projects. Links still to be added to presentations and/or pull requests.

• Andrea Marini:
  • implementation of optimal sorting networks in HLS (done)
  • integration of vertex emulation in the correlator layer 1 (hackathon project, done)
  • development of the correlator layer 1 demonstrator in the forward HGCal region (2.5 < |η| < 3.x)
• Emmanouil “Manos” Vourliotis (Athens student):
  • training of BDT IDs for pileup rejection and PF e/gamma identification in HGCal (done)
  • development of an emulator for the correlator layer 2 de-regionizer firmware & testing in CMSSW (~done)
  • development of the e/γ final sorter modules for correlator layer 1, together with Simranjit (hackathon project + followup)
• Ioannis Bestintzanos (Ioannina student):
  • implementation of reconstruction of jets with different radius in the seeded-cone jet firmware (started)
• Juliette Alimena:
  • development of firmware to interface GMT with Correlator Layer 1 (hackathon project)
• Michael Pitt:
  • comparison of e/gamma and PF BDT trainings of HGCal ID (done)
• Matthias Komm:
  • development of a NN for vertex reconstruction (GTT) and track-vertex-assignment (correlator layer 1)
• Nadezda “Nadya” Chernyavskaya:
  • development of firmware to interface GMT with Correlator Layer 1 (hackathon project, + followup?)
  • study of the performance of the PF muon identification (started)
• Santeri Laurila:
  • study of JetID variables (done)
  • development of JEC firmware
• Simranjit Singh Chhibra:
  • study of the use of e/m energy interpretation in PF (done)
  • development of the e/γ final sorter modules for correlator layer 1, together with Manos (hackathon project + followup)
  • study of HGCal 3D trigger primitive algorithms & their impact on PF (starting)
• Sioni Paris Summers:
  • development of the de-regionizer firmware (~done)
  • development of the seeded-cone jet algorithm & firmware (~done)
  • development of firmware for jet tagging in collaboration with the Hamburg group
  • development and integration of firmware for a JetMET demonstrator for correlator layer 2
• Thea Aarrestad:
  • development of the seeded-cone jet algorithm (done)
  • development of jet tagging in collaboration with the Hamburg group
  • development of firmware for sums to run in the JetMET layer 2 demonstrator (hackathon project + followup)