The ATLAS Trigger System in Run-2 Rhys Owen 1 University of - PowerPoint PPT Presentation

The ATLAS Trigger System in Run-2 Rhys Owen 1 University of Birmingham 1 14 Febuary 2018 Particle Physics Seminar Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 1 / 29

Introduction In Run-2 of the LHC increased centre-of-mass energies and instantaneous luminosity have lead to increases in the trigger rate but this is constrained by hardware requirements. The easiest solution to reduce the rate again would be to increase the energy thresholds used by the trigger, however this would severely curtail the ATLAS physics programme. This required significant upgrades at Level-1 and optimisations in the HLT to maintain signal efficiency while reducing the rate of events. 3 × 10 Entries / 2 GeV 60 W → e ν ATLAS 50 -1 13 TeV, 81 pb 40 Data MC Stat. ⊕ Syst. Unc. W e → ν 30 Multijet Z → e + e - 20 W → τ ν Other backgrounds 10 0 Data / Pred. 1.2 1.1 1 0.9 0.8 20 30 40 50 60 70 80 90 100 p e [GeV] T Phys. Lett. B 759 (2016) 601 EgammaTriggerPublicResults Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 2 / 29

The ATLAS Detector Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 3 / 29

The ATLAS Detector: Sub-detectors General purpose detector at the LHC. Several detector technologies and components used to detect and identify final state particles. Can be roughly split into layers, tracking, calorimetry and muon spectrometry. Responsibility of the trigger and data acquisition system to select and record “interesting” events at a reduced rate to disk. Due to detector design different information available to trigger system as the trigger decision progresses. Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 4 / 29

Run 2 Conditions LHC bunches filled with protons collide at 40 MHz Providing an instantaneous luminosity which peaked at 20 . 6 × 10 33 cm − 2 s − 1 This leads to a large number of p-p interactions which could all produce a signature of interest. ] /0.1] -1 s 350 ATLAS Online Luminosity ∫ s = 13 TeV -1 -2 ATLAS Online, 13 TeV Ldt=86.5 fb 25 -1 cm LHC Stable Beams Recorded Luminosity [pb 300 µ 2015: < > = 13.4 × 33 33 Peak Lumi: 20.6 10 cm -2 s -1 µ 2016: < > = 25.1 Peak Luminosity per Fill [10 20 µ 250 2017: < > = 38.1 µ Total: < > = 32.0 200 15 150 10 initial 2017 calibration 100 initial calibration 5 50 0 0 0 10 20 30 40 50 60 70 80 01/05 02/06 05/07 07/08 08/09 11/10 12/11 15/12 Mean Number of Interactions per Crossing Day in 2017 https://twiki.cern.ch/twiki/bin/view/AtlasPublic/LuminosityPublicResultsRun2 Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 5 / 29

The ATLAS Detector: Trigger / DAQ 40 MHz Calorimeter detectors TileCal Muon detectors Detector Level-1 Calo Level-1 Muon Read-Out Endcap Barrel Preprocessor ... sector logic sector logic FE FE FE nMCM CP (e,γ,τ) JEP (jet, E) ROD ROD ROD 100 kHz CMX CMX MUCTPI Level-1 Accept DataFlow L1Topo Read-Out System (ROS) CTP CTPCORE CTPOUT Pixel/SCT Central Trigger Level-1 Data Collection Network RoI Fast TracKer (FTK) High Level Trigger Level-1 - reduced granularity Data Storage (HLT) Accept information at full rate Processors Event Tier-0 Data HLT - full granularity ≈ 1 . 5 kHz information at reduced rate Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 6 / 29

Level-1 Trigger Calorimeter detectors TileCal Muon detectors Level-1 Calo Level-1 Muon Level-1 - reduced granularity Endcap Barrel Preprocessor sector logic sector logic nMCM information at full rate CP (e, γ , τ ) JEP (jet, E) MUCTPI CMX CMX Level-1 Accept Hardware based trigger L1Topo Primarily derived from calorimeter CTP CTPCORE and muon systems CTPOUT RoI Central Trigger Provides a rate reduction from Level-1 40 MHz to 100 kHz limited by the maximum readout rate of the front end electronics. Also provides Regions Of Interest (ROIs) as the starting point for software algorithms. Significant hardware and firmware updates in Run-2 EventDisplayRun2Physics Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 7 / 29

Level-1 Trigger: Updates The largest update was the inclusion of Topological triggering Calorimeter detectors with the L1Topo module. TileCal Muon detectors Level-1 Calo Other systems need to provide Level-1 Muon Endcap Barrel Preprocessor sector logic sector logic nMCM L1Topo with information CP (e, γ , τ ) JEP (jet, E) This is done with Trigger OBjects MUCTPI CMX CMX Level-1 Accept (TOBs) which represent the L1Topo CTP potential physics objects which have CTPCORE CTPOUT been detected. RoI Central Trigger Level-1 Similar to the ROIs which are sent to the HLT. Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 8 / 29

Level-1 Trigger: L1Calo The Level-1 calorimeter trigger. Analogue sum of calorimeter cells provided by both electromagnetic and hadronic calorimeter. Fast digitisation performed to produce “trigger towers” (typically 0 . 1 × 0 . 1 in ∆ η × ∆ φ ) Separate sub-systems then search for clusters compatible with electromagnetic, tau and hadronic jet like energy deposits Cables carrying analogue signals from calorimeters. Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 9 / 29

Level-1 Trigger: L1Calo The Level-1 calorimeter trigger. Analogue sum of calorimeter cells provided by both electromagnetic and hadronic calorimeter. Fast digitisation performed to produce “trigger towers” (typically ! 0 . 1 × 0 . 1 in ∆ η × ∆ φ ) ! ! Hadronic Separate sub-systems then search ! calorimeter for clusters compatible with Electromagnetic calorimeter electromagnetic, tau and hadronic Trigger towers ( "# × "$ = 0.1 × 0.1) jet like energy deposits Electromagnetic Vertical sums ! isolation ring The electromagnetic algorithm is Horizontal sums ! Hadronic inner core based on windows such as this, and isolation ring Local maximum/ where the sums of towers around a Region-of-interest JINST 3 (2008) P03001 local maximum are calculated. Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 9 / 29

Level-1 Trigger: L1Calo - Run 2 Upgrades Digitisation 2.5 Average L1_XE50 rate / bunch [Hz] ◮ nMCM - new Multi Chip Module, ATLAS Operations updated digitisation and dynamic 2 2015 Data, s = 13 TeV baseline subtraction. 50 ns pp Collision Data Processing 1.5 without pedestal correction ◮ CPM - Cluster Processor Module, with pedestal correction updated algorithm to allow 1 E T -dependent isolation Architecture 0.5 ◮ CMX - Common Merger eXtended, merge Trigger OBjects 0 (TOBs) instead of threshold 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 counts and forward to the Level-1 30 -2 -1 Instantaneous luminosity / bunch [10 cm s ] topological system. L1CaloTriggerPublicResults Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 10 / 29

Level-1 Trigger: L1Calo - Run 2 Upgrades Digitisation ◮ nMCM - new Multi Chip Module, updated digitisation and dynamic 1.4 Efficiency ATLAS Preliminary baseline subtraction. 1.2 -1 Data 2016, s =13 TeV, 60.3 pb Processing 1 ◮ CPM - Cluster Processor Module, 0.8 updated algorithm to allow 0.6 E T -dependent isolation 0.4 L1_EM20VH Architecture 0.2 L1_EM20VHI ◮ CMX - Common Merger 0 0 10 20 30 40 50 60 70 80 90 100 eXtended, merge Trigger OBjects E [GeV] T (TOBs) instead of threshold EgammaTriggerPublicResults counts and forward to the Level-1 topological system. Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 10 / 29

Level-1 Trigger: L1Muon TGCs Large ( odd numbered ) sectors η =1.0 y 12 m RPCs 5 10 η =1.3 BOL 1 2 3 4 5 6 4 EEL 2 8 The Level-1 muon trigger is based BML 1 2 3 4 5 6 1 3 on dedicated triggering chambers 6 EIL4 1 2 3 4 5 6 BIL η =1.9 RPCs (TGCs) found in the barrel 3 2 4 2 EEL EIL End-cap 2 TGCs TileCal End-cap (endcap) η =2.4 1 toroid TGC-FI magnet 1 2 CSC z 0 0 2 4 6 8 10 12 14 m 16 Eur. Phys. J. C 77 (2017) 317 Green: Active, Red: Ready for 2018 data taking. Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 11 / 29

Level-1 Trigger: L1Muon - Run 2 Upgrades Algorithm ◮ Additional logic requiring a TGCs Large ( odd numbered ) sectors η =1.0 coincidence between the inner y 12 m TGC layers (TGC-FI) or the RPCs 5 TileCal and the outer layers. 10 η =1.3 BOL 1 2 3 4 5 6 Reducing the trigger rate by up to 4 EEL 2 8 10% for the unprescaled muon BML 1 2 3 4 5 6 trigger. 1 3 6 EIL4 Coverage 1 2 3 4 5 6 BIL η =1.9 3 2 4 ◮ Additional RPC chambers made 2 EEL EIL TileCal End-cap 2 TGCs End-cap η =2.4 1 operational in the bottom of the toroid TGC-FI magnet 1 2 CSC spectrometer increase coverage by z 3 . 6%. 0 0 2 4 6 8 10 12 14 m 16 Architecture Eur. Phys. J. C 77 (2017) 317 Green: Active, Red: Ready for 2018 data ◮ An additional module taking. Arrow indicates path of background MUCTPI2TOPO was introduced beam particle. to transmit muon TOBs to the Level-1 topological system. Rhys Owen (University of Birmingham) The ATLAS Trigger System in Run-2 14 Feb 2018 12 / 29