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Pre-Production Validation of the ATLAS Level-1 Calorimeter Trigger System

Pre-Production Validation of the ATLAS Level-1 Calorimeter Trigger System. ATLAS Level-1 Calorimeter Trigger Collaboration:.

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Pre-Production Validation of the ATLAS Level-1 Calorimeter Trigger System

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  1. Pre-Production Validation of the ATLAS Level-1 Calorimeter Trigger System ATLAS Level-1 Calorimeter Trigger Collaboration: R. Achenbach1, C. Ay2, B.M. Barnett3, B. Bauss2, A. Belkin2, C. Bohm4,I.P. Brawn3, A.O. Davis3, J. Edwards3, E. Eisenhandler5, F. Föhlisch1,C.N.P. Gee3, C. Geweniger1, A.R. Gillman3, P. Hanke1, S. Hellman4,A. Hidvégi4, S.J. Hillier6, E.-E. Kluge1, M. Landon5, K. Mahboubi1,G. Mahout6, K. Meier1, A. Mirea3, T.H. Moye6, V.J.O. Perera3,W. Qian3, S. Rieke2, F. Rühr1, D.P.C. Sankey3, U. Schäfer2,K. Schmitt1, H.-C. Schultz-Coulon1, S. Silverstein4, R.J. Staley6,S. Tapprogge2,J.P. Thomas6, T. Trefzger2, D.Typaldos6,P.M. Watkins6, A. Watson6, G.A. Weber2, P. Weber1 1Kirchhoff-Institut für Physik, University of Heidelberg, Heidelberg, Germany2Institut für Physik, University of Mainz, Mainz, Germany3CCLRC Rutherford Appleton Laboratory, Oxon, UK4Fysikum, University of Stockholm, Stockholm, Sweden5Physics Department, Queen Mary, University of London, London, UK6School of Physics and Astronomy, University of Birmingham, Birmingham, UK Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  2. Pre-Production Validation of the ATLAS Level-1 Calorimeter Trigger System • Trigger Architecture • Module Design and Challenges • Testing Methodologies: • Software data verification • Real-time link stability measurements • Test-beam performance Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  3. Level-1 triggering in ATLAS Calorimeters Muon Detectors • All data buffered at bunch-crossing rate of 40 MHz for 2.5 ms • Three-stage triggering system • Level-1: custom built hardware, fixed latency – target rate 75 kHz • Level-2: software, RoI based selection – target rate 1000 Hz • Event Filter: software, full detector – target rate 200 Hz • Level-1 has three sub-systems: • Calorimeter Trigger • Muon Trigger • Central Trigger (CTP) Calorimeter Trigger Muon Trigger e/γ tau jet ET ΣET μ Central Trigger Processor Level-1 Trigger Trigger to Front-end Buffers Regions of Interest (RoI) To Level-2 Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  4. < 1μs ~2000 Tile Calorimeter Trigger Towers ~100 bits (0.5 Gbyte/s) Central Trigger 300 Gbyte/s ~5000 Liquid Argon Calorimeter Trigger Towers Real time (40 MHz) Intermediate data Region of Interest data Triggered read out (75 kHz) Readout System Level-2 Trigger 50 ns Calorimeter Trigger Requirements Calorimeter Trigger Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  5. Readout Data Readout Driver (ROD) 14 modules Region of Interest ROD 6 modules Region of Interest Data Calorimeter Trigger Architecture Digitized Energies Cluster Processor 56 modules Merging 8 modules Features: Realtime Path: Fixed Latency Pipelined Many stage processing Massive parallelism Dual purpose modules Heavily FPGA based Merged Results To CTP Calorimeter Signals Preprocessor 124 modules Jet/Energy Processor 32 modules Merging 4 modules Real-time Data Path Five Types of Custom 9U Modules PPM CPM JEM CMM ROD Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  6. Playback Memory Processing… Spy Memory Generic Module Design Merging Stage 1-2 FPGA Processing Stage 1-8 FPGA Input Stage 1-20 FPGA • Challenges: • Many FPGAs • High connectivity • Internal • External (via backplane) • High speed signals High Density Back-plane Connector (~1150 pins) Signal Speeds up to: 400 Mbit/s differential 160 Mbit/s single ended Readout Readout output up to 800 Mbit/s Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  7. Merging Processing Input A real example: theCluster Processing Module • Backplane Connector i/o • Input: ~58 Gbit/s • Output: ~28 Gbit/s • Input Stage: • 20 FPGAs • Processing Stage: • 8 FPGAs • Merging Stage: • 2 FPGAs • Modules Needed: 56 Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  8. Detailed Module Simulation Runs in parallel with hardware Predicts output data at any stage Requires generation of synchronised trigger patterns Test-beam operation Analogue inputs vs Calorimeter data Digital processing integrity Module Testing Goals and Tools • High speed link stability and performance • Use data integrity to establish good timing windows • High statistics mode measurements in real-time • Parity error counting • Dedicated firmware loads • Algorithm correctness • Use specially designed test-vectors, eg: • Physics-like • Boundary conditions • Data formatting • Read-out must conform to external expectations • System Integration • Does the complete chain work as a trigger? Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  9. Simulation architecture and usage Online Database: Modules present Cabling Configuration Test Vectors Trigger Pattern • Generic C++ framework • VHDL inspired • Processes, Ports, Links • Hierarchical, Scalable • Output ‘Driven’ Configure hardware (data in playback memories) Run simulation Run hardware Simulation Results Read hardware (spy memories, readout) Compare Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  10. Artificial trigger generation Continuous: eg 50 kHz ‘Bursty’:eg Bursts of 5 triggers • To predict readout data need to control trigger generation • Also need to test hardware with high rate and ‘difficult’ trigger patterns • Done via a custom module plus trigger pattern generation (under user control) • Triggers synchronised to playback memories • Simulation also knows about trigger pattern • Many types of pattern possible Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  11. CPM input LVDS timing windows 20 • Input FPGAs receive 40 Mbit/s signals • Input strobing requires timing • Timing window: 20ns over whole module • Once optimised, check with firmware • No error in 10 minutes in whole module = bit error rate < 1 in 1013 16 Input FPGA Identifier Timing structure derived from PCB layout 12 Error Free Window ~20 ns 1200 8 800 Error Count 4 400 0 0 0 5 10 15 20 25 0 5 10 15 20 25 Strobe Phase (ns) Strobe Phase (ns) Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  12. Processor FPGA timing windows • Jet/Energy Processor FPGAs: 385 inputs at 80 MHz 210 on-board, 165 from backplane • Cluster Processor FPGAs: 108 inputs at 160 MHz 60 on-board, 48 from backplane Error Free Window ~8 ns Error Free Window ~2.5 ns 2000 1000 1600 800 Error Count Error Count 1200 600 800 400 400 200 0 0 0 5 10 15 20 25 0 0 5 10 15 20 25 Strobe Phase (ns) Strobe Phase (ns) Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  13. ATLAS Combined Test-beam 2004 12 Cables: 8 CPM 4 JEM • Level-1 Calorimeter Trigger present September to mid-October • Triggered successfully for part of the time by L1Calo • A full slice through the trigger system • ~1% of final capacity Pre-processor Energy Merger Cluster Processor Jet Processor Hit Merger 5 Readout Links Calorimeter Signals: 32 in 8x2x2 array Readout RoI Readout Readout Readout Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  14. The Reality Readout Drivers Cluster/Jet/Energy Processors Pre-processor Receivers Interface to Test-beam Trigger, Timing .... Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  15. Checks on Test Beam data • Internal Consistency checks • Assume full granularity input data is correct • Are all other data (energies, hits etc) consistent? • Performed in ~500,000 events • Only minor problems, identified as firmware features • No evidence of data integrity problems • Comparisons with Calorimeters • Good correlation was seen • With some problems – overlapping pulses? • Triggers generated on genuine physics events Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  16. Cluster processor hit results 1000 • Four thresholds • 20, 50, 100, 200 GeV • Hit results are as expected • RoIs also checked • Positions, hits all formed correctly events with no cluster hits just one threshold passed 100 10 Event Count just two thresholds passed three or more thresholds passed Cluster Energy (GeV) Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  17. Jet/energy algorithm results • Only one threshold used • 170 GeV • No errors seen in hits • No errors seen in energy sums Event Count 104 events with jet hit Event Count events with no jet hits 103 102 Jet Energy (GeV) Jet Energy (GeV) Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  18. Correlation with calorimeters • Liquid Argon comparison: • ~factor 2 scaling (ET) • Lose energy in some events: overlapping events? bunch-crossing identification problem? • Tile comparison: • Very encouraging • Saturation at ~225 GeV understood Electromagnetic Energy (GeV) Hadronic Energy (GeV) 0 50 100 150 200 250 300 350 Trigger Energy (GeV) Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

  19. Did the Trigger Work? • Run with Cluster Threshold of 20 GeV as CTP trigger • Clear cut-off in Electromagnetic Energy as Measured by Liquid Argon Detector Jet and Energy Triggers also used in other runs Trigger Energy (GeV) E.M. trigger threshold Calorimeter Energy (GeV) Validation of ATLAS Level-1 Calorimeter Trigger, Stephen Hillier

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