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Online Physics Event Selection: The e / g Slice Steve Armstrong Brookhaven National Laboratory on behalf of the ATLAS Trigger community 6 October 2004 ATLAS Overview Week Freiburg, Germany 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 1 OUTLINE ¶ OVERVIEW OF THE HIGH-LEVEL TRIGGER (HLT) ¶ COMPONENTS OF E/GAMMA SELECTION ¶ PERFORMANCE: STAND-ALONE AND ANALYSIS-LEVEL ¶ DEPLOYMENT CHALLENGES ¶ COMBINED TESTBEAM ACTIVITIES ¶ SUMMARY 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 2 THE ATLAS TRIGGER SYSTEM: THREE LEVELS See P. Conde Muíño’s talk from Monday Rates 40 MHz LEVEL-1 TRIGGER •Hardware-Based (FPGAs ASICs) •Coarse granularity from calorimeter & muon systems •2 ms latency (2.5 ms pipelines) ~75 kHz LEVEL-2 TRIGGER •Regions-of-Interest “seeds” •Full granularity for all subdetector systems •Fast Rejection “steering” •O(10 ms) target CPU time ~2 kHz EVENT FILTER •“Seeded” by Level 2 result •Full event access •Offline-like Algorithms •O(1 s) target CPU time 200 Hz High-Level Trigger FIRST PART OF ATLAS RECONSTRUCTION AND PHYSICS EVENT SELECTION 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 3 HIGH-LEVEL TRIGGER OUTPUT RATE COMPOSITION Object Physics coverage Low Luminosity 2×1033 cm-2s-1 Rates (Hz) Electrons Higgs, new gauge bosons, extra dimensions, SUSY, W, top e25i, 2e15i ~40 Photons Higgs, extra dimensions, SUSY g60, 2g20i ~40 Higgs, new gauge bosons, extra dimensions, SUSY, W, top m20i, 2m10 ~40 2m6 + m+ m- + mass cut ~25 j400, 3j165, 4j110 ~20 j70 + xE70 ~5 35i + xE45 ~10 Muons Jets Rare b-decays (e.g., BmmX, BJ(’)X) SUSY, compositeness, resonances Jet+missing ET SUSY, leptoquarks Tau+missing ET Others Extended Higgs models (e.g., MSSM), SUSY Prescaled, calibration, monitoring Total HLT Output Rate 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg ~20 ~200 4 TRIGGER EVENT SELECTION (e.g., ELECTRONS) LVL1 Calo RoI HLT STEERING PROVIDES FAST REJECTION Step-based execution of sequences of seeded Algorithms This flexibility has direct impact upon physics performance potential HZZ 2e2m LVL2 Calo Algorithm Reject or Accept LVL2 Tracking Algorithms Reject or Accept EF Calo Algorithm Reject or Accept EF Tracking Algorithms Reject or Accept Event Accepted 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 5 HIGH-LEVEL TRIGGER DATA ACCESS MODEL REGION OFFLINE IDENTIFIERS OFFLINE IDENTIFIERS ONLINE IDENTIFIERS RAW DATA DATA OBJECTS DATA OBJECTS 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg “ByteStream” of raw data organized as if it were coming from the detector electronics 6 OUTLINE ¶ OVERVIEW OF THE HIGH-LEVEL TRIGGER (HLT) ¶ COMPONENTS OF E/GAMMA SELECTION ¶ PERFORMANCE: STAND-ALONE AND ANALYSIS-LEVEL ¶ DEPLOYMENT CHALLENGES ¶ COMBINED TESTBEAM ACTIVITIES ¶ SUMMARY 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 7 LEVEL-2 TRACK RECONSTRUCTION ALGORITHMS (Pixel & SCT) SiTrack algorithm uses 3-point combinations from Pixel and SCT – tuned for b-tagging and B physics IDSCAN algorithm processing steps Z VERTEX FINDING Determine interaction zv position (3s 17 cm) e 97%, s 200 mm HIT FILTER SP groups compatible with track from zv GROUP CLEANER Groups form track candidates; remove noise Pixels TRACK FIT Fit Track Parameters Preliminary SCT Reconstructed Track 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 8 LEVEL-2 TRACK RECONSTRUCTION: EXAMPLE OF IDSCAN WITH ELECTRON RoI (Dh × Df = 0.2 × 0.2) Only ~7 good hits in ~200 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 9 LEVEL-2 TRACKING ALGORITHMS (TRT) TRTxK TRTLUT • Core of algorithm is set of utilities from xKalman++ • Based on Hough-transform • Track candidates identified from peaks in histogram • Tracks must pass quality cuts and must lie on maximal number of drift circle positions with drift information • Initial Track Finding with LookUp Table (LUT) considering all TRT hits belonging to number of predefined tracks • Local Maximum Finding with 2D histogram in f and 1/pT • Track Splitting by analyzing pattern of hits for a Track • Track Fit using third-order polynomial 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 10 LEVEL- 2 CALORIMETER RECONSTRUCTION ALGORITHM Processing steps of T2CALO at each step via HLT Steering mechanism, data request is made and accept/reject decision is possible E3x7/E7X7 in EM Sampling 2 (E1-E2)/(E1+E2) in EM Sampling 1 g p0 7 October 2004 Steve Armstrong Total Electromagnetic Energy Hadronic (Tile & EM HEC) Energy Photon Selection Strategy • Shower shape analysis to reject dominant background from jets with a leading p0 • Possibility to use track veto - identify conversions first ATLAS Overview Week Freiburg 11 LEVEL- 1 “POSTDICTION” AT LEVEL-2 (CALORIMETER) • Level-1 “postdiction” implemented inside Level-2 Calorimeter algorithm (T2CALO) • Monitoring/cross-checking/comparison of Level-1 trigger decisions In Level-2 Software • • • • EM Cluster Energy EM Isolation Energy Had Core Energy Had Isolation Energy 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 12 OUTLINE ¶ OVERVIEW OF THE HIGH-LEVEL TRIGGER (HLT) ¶ COMPONENTS OF E/GAMMA SELECTION ¶ PERFORMANCE: STAND-ALONE AND ANALYSIS-LEVEL • Electron and photon triggers • Higgs Searches • Studies with Z→e+e− ¶ DEPLOYMENT CHALLENGES ¶ COMBINED TESTBEAM ACTIVITIES ¶ SUMMARY 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 13 PERFORMANCE STUDIES: ELECTRON TRIGGER e25i at Low Luminosity Efficiency % Rates L1 95.5 0.2 8.6 kHz L2Calo 92.9 0.3 1.9 kHz EFCalo 90.0 0.4 1.1 kHz EFID 81.9 0.4 108 Hz EFIDCalo 76.2 0.4 46 (±4) Hz Preliminary HLT Steering Configurable and Flexible Selection (i.e., which algorithms to run where) allows tuning of rates within resource limits and efficiencies 1034 cm-2s-1 2e15i at Low Luminosity Efficiency % Rates L1 94.4 0.5 3.5 kHz L2Calo 82.6 0.9 159 Hz EFCalo 81.2 1.0 110 Hz EFID 69.2 1.0 5.6 Hz EFIDCalo 57.3 1.5 1.9 (±2) Hz Preliminary 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 14 ELECTRON/PHOTON TRIGGER STUDIES FOR STANDARD MODEL HIGGS BOSON SEARCHES Higgs Search Channel Low Luminosity High Luminosity H ZZ* 4e e25i or 2e15i e30i or 2e20i 2e pT>7 GeV/c & 2e pT>20 GeV/c in h< 2.5 H ZZ* 2e2m e25i or 2e15i e30i or 2e20i 2ℓ pT>7 GeV/c & 2ℓ pT>20 GeV/c in h< 2.5 H WW*ee (VBF) e25i or 2e15i 2e pT>15 GeV/c in h< 2.5 H gg g60i or 2g20i g60i or 2g20i Kinematic Criteria 1g pT>40 GeV/c & 1g pT> 25 GeV/c in h< 2.4 (barrel/endcap crack excluded) • Trigger efficiencies are for leptons in acceptance of h< 2.5 • Event sample simulation: Pythia 6.2 and with Geant3 full simulation and reconstruction including electronic noise and pile-up. 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 15 ELECTRON TRIGGER STUDIES FOR HIGGS BOSON SEARCHES: ANALYSIS-LEVEL RESULTS Preliminary Trigger Element Luminosity H4e H2e2m (130 GeV/c2) (130 GeV/c2) e25i or 2e15i Low 96.7 % 76.9 % e30i or 2e20i High 95.5 % 71 % g60i or 2g20i Low Hee (170 GeV/c2) Hgg (120 GeV/c2) 89.5 % 83 % Efficiency (%) Muon triggers (i.e., m20i, 2m10, m10 + e15i) not yet included 100 98 96 94 92 90 H4e H → 4e • First complete study of trigger and offline selection of Higgs boson search efficiencies with full detector simulation Low LowLuminosity Luminosity 0 7 October 2004 100 200 300 Higgs Mass (GeV/c2) Steve Armstrong 400 • Preliminary: trigger performs adequately for low mass Higgs searches with e/g final states • More studies of this type are needed across all Physics Groups (Trigger-aware analyses are essential)! ATLAS Overview Week Freiburg 16 TRIGGER EFFICIENCY FROM DATA with Z→e+e− SINGLE TAG: e25i Level2 z 1 offline N events offline Nz2 events DOUBLE TAG: 2e25i Level2 Ni f Z N0 f Z N0 where f and f are fraction of true and fake Z' s in sample N e z 1 rec ztrue (2e trig electrue e z trig 2 electrue z ) f z N0 e rec z fake (2e trig elecfake 2 trig e 2 trig elecfake ) f z N0 trig rec N z2 e zrec e f N e z 0 z fake e elecfake f z N 0 true electrue 2 Assumptions which need further study trig eelec Efficiencies (%) Level-2 Calo & ID Track Matching tru e trig e = elec fa ke fz fz = = 1 e trig e trig 2 N z2 z N 2 N1z This Method MC Truth TDR 87 ± 1 87 ± 0.6 86.6 ± 0.6 17 OUTLINE ¶ OVERVIEW OF THE HIGH-LEVEL TRIGGER (HLT) ¶ COMPONENTS OF E/GAMMA SELECTION ¶ PERFORMANCE: STAND-ALONE AND ANALYSIS-LEVEL ¶ DEPLOYMENT CHALLENGES ¶ COMBINED TESTBEAM ACTIVITIES ¶ SUMMARY 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 18 DEPLOYMENT CHALLENGES OFFLINE SOFTWARE SYSTEM PERFORMANCE HLT INFRASTRUCTURE RAW DATA 7 October 2004 • HLT is strongly coupled to Offline software – Avoids duplication of work (e.g., similar reconstruction algorithms) – Simplification of migration of selection power – Simplification of performance studies – Common database access tools – Raw Data Converters written by experts from detector groups • Software development instability makes progress difficult • Within limits of Level-2 and EF processing time: – Data Transfer over network – Software framework overhead – Raw data conversion – Algorithm processing time • Evaluate concurrently with software development • • • • Algorithms and core software must run on HLT Infrastructure Level-2 should be multithreaded Interaction with Online DataFlow software HLT software must run for at least several hours (millions of events!) without difficulty (e.g., memory leaks, crashes) • HLT (especially Level-2) is very sensitive to ROD data formats and functionality and associated decoding software • Incomplete/corrupt/imperfect detector data must be anticipated (fault tolerance) Steve Armstrong ATLAS Overview Week Freiburg 19 OFFLINE RELEASES AND HLT SOFTWARE Highly Active Offline Software Development → Frequent Releases e.g., 8.0.0 31 Mar. 8.0.1 16 Apr 8.0.2 8 May 8.0.3 19 May 8.1.0 27 April 8.0.4 30 May 8.2.0 27 May 8.0.5 14 Jun 8.3.0 18 Jun 8.0.6 26 Jul 8.4.0 7 Jul 8.5.0 23 Jul 8.0.7 27 Aug. 8.6.0 14 Aug. Time 8.7.0 2 Sept. 8.8.0 Early Oct. High-Level Trigger Software: Stability and Time required for… Integration: 1-2 weeks HLT SW DataFlow SW Offline SW Online SW Common (e.g., Event Format) 7 October 2004 Development, Testing, Deployment: t(FTEs) > few weeks • Heavy use Offline Services/Tools (e.g., ByteStream Converter for Data Preparation, some only used by LVL2) • Validation (or even development) work starts when most other tools (including reconstruction) are validated • Feedback loop is needed (e.g., reconstruction does not work with seeding or is too slow,…) • HLT/Offline lag: HLT developers using old releases • Difficult to achieve fixes in these releases (Offline already moved on, sometimes more than two cycles) HLT/SPMB interactions on this issue are on-going – propose adding more frequent and detailed HLT-related tests to development cycle. Steve Armstrong ATLAS Overview Week Freiburg 20 SYSTEM PERFORMANCE OF LEVEL-2 ALGORITHMS Data Preparation is largest consumer of processing time, hence essential that data access granularity be as fine as possible and processing be restricted (RoI) REGION OFFLINE IDENTIFIERS OFFLINE IDENTIFIERS ONLINE IDENTIFIERS RAW DATA DATA OBJECTS DATA OBJECTS “ByteStream” of raw data organized as if it were coming from the detector electronics LVL2 Calorimeter Algorithm Performance Algorithm has smallest contribution to processing time!! Timing is under control, especially when extrapolated to expected 2007 CPU performance, but every 1 ms of “first stage” Level-2 processing requires O(100) Processing Units! 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 21 LEVEL-2 SOFTWARE DEPLOYMENT STRATEGY GAUDI with support for multiple threads CONFIG CONFIG psuedoROS Selection SW Steering Data Manager Supervisor Config Manager Online Online Control HLT-Onl. I/F Steering Controller HLT-DC I/F AppControl Connnection to ROBs Input Dispatch Online Sequence Diagram for Level-2 Event Selection Processing Offline Data Flow ATHENA Environment L2PU athenaMT Steering Controller get configuration Link to algorithm libraries Steering Controller configure Algorithms NextEvent L1 Result Algorithms worker thread (event selection) L1 Result DataRequest athenaMT: Offline Level-2 Development Environment Data L2 Result L2 Result L2Decision L2Result NextEvent EoR EoR L2PU PSC 7 October 2004 HLT SELECTION SOFTWARE L2PU Steve Armstrong • • • • • Emulates complete L2PU environment Supports multiple threads No need to setup Data Flow systems Run like normal offline application Level-2 Developers must follow a set of Coding guidelines which are more strict than Offline development guidelines ATLAS Overview Week Freiburg 22 SOFTWARE TESTS WITHIN HLT INFRASTRUCTURE TESTBEDS ARE THE HLT EQUIVALENT OF TESTBEAM(S) CERN Network Building 32 ROS LVL2 EventBuilder Event Selection SW Buildin g 513 Event Filter Test made on e/g Slice using configuration above including: • ROS containing calorimeter data for simulated LVL1 selected events • Level-2 result successfully transmitted to EF selection • Level-2 ran Calorimeter (T2Calo) algorithm, Event Filter ran CaloRec Algorithm Confirmed and validated functionality of full HLT slice (LVL2+EF). i.e., transfer Level-2 result to EF and compare (inside EF) that it matched with what the EF reconstructed 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 23 RAW DATA FORMAT AND DATA PREPARATION • Online DSP code for calculation of E, t, c2 from ADC counts 5 E a i (Si P ed) i 1 5 ADC Samplings Recent Example LAr ROD FUNCTIONALITY IN CTB 5 E t b i (Si P ed) i 1 5 χ 2 (Si P ed E g i ) 2 i 1 • Level-2 needs this functionality for Calorimeter Trigger data access and preparation (in progress for CTB) FAULT TOLERANCE 7 October 2004 • HLT faults are likely to be in one of four categories • Hardware problems in processing node • Operating system problem in processing node • Communication problems • Problems in Event Selection Software • Experience from CTB with Event Selection Software: • Incomplete data received • Corrupted, noisy, too large data • Converter problems, crashes Steve Armstrong ATLAS Overview Week Freiburg 24 OUTLINE ¶ OVERVIEW OF THE HIGH-LEVEL TRIGGER (HLT) ¶ COMPONENTS OF E/GAMMA SELECTION ¶ PERFORMANCE: STAND-ALONE AND ANALYSIS-LEVEL ¶ DEPLOYMENT CHALLENGES ¶ COMBINED TESTBEAM ACTIVITIES ¶ SUMMARY 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 25 LEVEL-2 EVENT RECONSTRUCTION OF CTB DATA 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 26 HLT ALGORITHM STUDIES WITH CTB DATA ARE IN PROGRESS: EXTREMELY PRELIMINARY “Offline” analysis of CTB data with HLT Algorithms: these recent results are extremely preliminary and are still being interpreted and understood. IDSCAN TRTxK SiTrack Very recent work with AthenaMT and ROD Data Preparation may allow Algorithms to run in “Real-Time” mode within CTB soon. 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 27 SUMMARY AND CONCLUSIONS • Trigger has three-level architecture with software-based High-Level Trigger • Events not selected by Trigger are not available for Physics Analyses • Development and testing of components of e/gamma selection are on-going • Eight Inner Detector Tracking and Calorimeter HLT reconstruction algorithms • Stand-alone trigger studies involve unification of many components of both Core Software and Algorithms • Physics Analysis-level studies have been done with encouraging preliminary results, but more are needed and essential! • Several challenges exist to e/gamma (and all HLT) slice deployment • Alignment with Offline Software development cycle • System performance • Integration within Testbeds • Raw data format and preparation • Progress is being made on several fronts • Experience of CTB has been valuable and is on-going • Infrastructure tests are being done • Algorithms run in Offline mode on CTB data - preliminary results being studied – with hopes for “real-time” test of some algorithms 7 October 2004 Steve Armstrong ATLAS Overview Week Freiburg 28