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L1Calo Intro

L1Calo Intro. Norman Gee. Cambridge Group, Dec 2008. Calorimeters Muons. Other detectors. 40 MHz. CALO trigger. MUONS trigger. hardware. Det. readout. L1A. CTP. 75 kHz. Level-1. <2.5 s. ROD. ROD. ROD. Regions of Interest (RoI). 120 Gb/s. RoI requests. DAQ. ROB. ROB.

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L1Calo Intro

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  1. L1Calo Intro Norman Gee Cambridge Group, Dec 2008

  2. Calorimeters Muons Other detectors 40 MHz CALO trigger MUONS trigger hardware Det. readout L1A. CTP 75 kHz Level-1 <2.5 s ROD ROD ROD Regions of Interest (RoI) 120 Gb/s RoI requests DAQ ROB ROB ROB RoIB L2SV ROS RoI Data 3 Gb/s L2N L2A. Event Builder 2 kHz EFN Software Level-2 <40 ms Full events EF Acc. Event Filter ~1 s 200 Hz 300 Mb/s High-level Trigger Trigger strategy • L1 • Dedicated hardware • (ASICS & FPGAs) • Calorimeters & muons • Latency < 2.5 s • L1A 75 kHz (Max 100kHz) • L2 • ~500 dual CPUs • Full granularity • Regions of Interest (~2%) • Latency ~40 ms • L2A 2kHz • Event Filter (L3) • ~1600 dual CPUs • Access to full event & calibration constants • More detailed reconstruction • Use Offline algorithms • Latency ~1s • 200Hz

  3. LAr Tile RPC TGC Muon Barrel Trigger Muon Endcap Trigger Preprocessor Jet/Energy Processor jets , ET Cluster Processor e/ , /h Muon-CTP Interface Central Trigger Processor RoIB Detector readout L2 supervisor Level-1 trigger system (L1) • 3 sub-systems • L1 - Calorimeters (L1Calo) • L1 – Muons (L1Muon) • Central Trigger Processor (CTP) • Signature identification • e/, /h, jets,  • Multiplicities per ET threshold • Isolation criterion • Missing ET, total ET, jetEET • CTP • Receive & synchronize trigger information • Generate level-1 trigger decision (L1A) • Deliver L1A to other sub-detectors

  4. L1 Calorimeter - Architecture • L1Calo partitioned into 3 sub-systems • Pre-Processor (PPr) • Receive & sample signal from calorimeters • Coarser granularity (Trigger Towers) • Noise filter • Bunch crossing identification (BCID) • Determine final ET value • Processors JEP & CP • Physics algorithms • Search for and identify: • isolated leptons, taus • jets • Compute ET total, missing,… • Real time transmission to CTP • DAQ + RoIs at each L1A (75kHz)

  5. Cryostat Hadronic Calorimeter – End cap Electromagnetic calorimeter - Endcap Forward Calorimeter Electromagnetic calorimeter - Barrel Tile Calorimeter Calorimeters

  6. Analogue summation of calorimeter cells • 3584 x 2 (EM+HAD) trigger towers Position  x  ||< 2.5 0.1x0.1 2.5 <||< 3.1 0.2x0.2 3.1 <||< 3.2 0.1x0.2 3.2 <||< 4.9 0.4x0.4125 trigger towers map Trigger towers (TT) LAr Tiles (semi-projective segmentation )

  7. Overview of the trigger front-end Long cables: • Cavern to USA15 • Typically 40–70m long • Detector responsibility • 256 TileCal, 360 LAr All analogue cables: • 16 individually shielded pairs • F/R denote front/rear of modules • All connectors D37 except TCPP inputs, which are D50 Short cables: • Internal to trigger racks • Typically 5–8m long • L1Calo responsibility • 776 in total

  8. Cable Installation

  9. Receivers (Rx) • Input signal conditioning to L1 (2,5V  250GeV) • Variable gain amplifier (VGA) • EET Conversion (Hadronic layers only, LAr already ET) • Local signal monitoring 10b PPr • Sampling • 40 Mhz, Flash-ADC 10 bits • 1 FADC count  250 MeV • Pedestal 40 FADC counts FIR filter a4 a3 a2 a1 a0 • Bunch crossing identification (BCID) • Finite impulse response filter (FIR) • Peak finder (linear/saturated) • Assign ET to the ‘correct’ bunch crossing + • ET calibration • Look-Up Table (LUT) • Pedestal subtraction, noise suppression • FADC (10b)  GeV (8b) conversion 10b 255 8b Ethres 1023 Pre-Processors – Energy reconstruction • Transmission to processors & DAQ

  10. PreProcessor Module (PPM)[Heidelberg] Multi-chip module (MCM) with FADCs, ASIC and LVDS serialisers Clock for FADC individually adjusted to sample on pulse peak. Then digital data synchronised (coarse & fine adjustment) to identical times. Towers for CP multiplexed, then serialised to 400 Mb/s and sent as LVDS on cables to CP For JEP, 2 x 2 em or Had towers summed, then sent at 400 MB/s to JEP RAW FADC values and LUT outputs are Read out when L1A fires

  11. Cluster Processor Algorithms and Regions of Interest (RoI) • Processor input is a matrix of tower energies • Algorithms look for physics signatures (sliding window) • RoI data sent to Level-2 trigger following L1A Jet/Energy-sum Processor ECAL+HCAL • Criteria for e/ or /h candidate: • EM or Had. cluster > Ethreshold • Total ET in EM Isolation Ring  EM isolation thresh. • Total ET in Had. Isolation Ring  Had. isolation thresh. • Local ET Maximum compared to neighbor windows. • e/ only: • Had. core  core isolation threshold • Jet candidate • Coarser granularity 0.2x0.2 (jet element) • Digital summation EM + Had. • Sliding, overlapping windows (3 sizes) • Missing energy

  12. Cluster Processor Module Readout Serialisers CP FPGAs

  13. Backplane Traffic 1 column of fan-out towers to adjacent CPM on ‘right’ (+η) Backplane Fan-in/out runs at 160 Mb/s to reduce pin count Output: hit counts. 3 bits for each of 8 threshold sets, + parity. 25 e/bits go left, 25 /hbits go right

  14. Backplane

  15. Jet-Energy module[Mainz/Stockholm]

  16. Common Merger Module

  17. Inputs # Thr Menu PreScale Mask Muons 6 x 3 bits 1MU10 & 1EM15 1 1 EM 8 x 3 bits 1EM1 1 1 Hadrons 8 x 3 bits 1TAU6 1 1 Jets 8 x 3 bits 1J4 1 1 L1A ET miss 8 bits NIM0 1 1 Jet ET 4 bits RNDM0 1 1 Et total 4 bits RNDM1 2 1 … … 1 0 256 items 160 entries Central Trigger Processor (CTP) • Receive, synchronize and align trigger information • Other signals: • Random trigger • Calibration • Minimum biais events (MBTS) • Generate the level-1 trigger decision (L1A) • Programmable trigger menu • Latency 100 ms (4BC) • Deliver the L1A to the other sub-detectors

  18. Average offset from L1A timing in EM layer Bunch crossing +2 +1 0 -1 -2

  19. Energy correlation with calorimeters Electromagnetic Hadronic L1Calo L1Calo • L1Calo reconstructed ET vs calorimeter precision readouts • Cosmic muons • Reasonable correlation achieved • Very crude calibration applied, still room for improvement

  20. Timing calibration • Internal timing of L1Calo trigger is achieved • Input timing realized in pre-processors • Not a trivial task • Several strategies depending on signal origin: • calibration • cosmic rays • collisions • Different setup & automatic procedures • Setup coarse/fine timing • Ensure signals are correctly sampled (3rd sample at maximum) • Signal shape with 1 ns sampling step • LAr EMB timing from pulser run • Coarse timing ok • Focusing on fine tuning

  21. Pedestal & Noise Electromagnetic Hadronic Mean ADC counts RMS • Pedestals set to 40 ADC counts • Sensible RMS ~ 400 MeV • Nearly all channels behaving correctly (>99%)

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