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wwwhephy.oeaw.ac.at/p3w/cms/trigger

http://wwwhephy.oeaw.ac.at/p3w/cms/trigger. CMS Detector at the CERN Large Hadron Collider. Cross sections for different processes vary by many orders of magnitude inelastic: 10 9 Hz W -> l n : 100 Hz tt: 10 Hz Higgs (100 GeV): 0.1 Hz

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wwwhephy.oeaw.ac.at/p3w/cms/trigger

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  1. http://wwwhephy.oeaw.ac.at/p3w/cms/trigger

  2. CMS Detector at the CERN Large Hadron Collider

  3. Cross sections for different processes vary by many orders • of magnitude • inelastic: 109 Hz • W ->ln: 100 Hz • tt: 10 Hz • Higgs (100 GeV): 0.1 Hz • Higgs (600 GeV): 0.01 Hz • Required selectivity • 1 : 10 10- 11 • Trigger - Cross Sections and Rates

  4. CMS Level-1 Trigger Only calorimeters and muon system involved Reason: no complex pattern recognition as in tracker required (appr. 1000 tracks at 1034 cm-2s-1 luminosity), lower data volume Trigger is based on: Cluster search in the calorimeters Track search in muon system

  5. Level-1 Trigger and Institute Responsibility Muon Trigger Calorimeter Trigger RPC CSC DT HF HCAL ECAL Local CSC Trigger Local DT Trigger RegionalCalorimeterTrigger PatternComparator Trigger CSC TrackFinder DT TrackFinder 40 MHz pipeline, latency < 3.2 ms GlobalCalorimeterTrigger 4+4 m 4 m 4 m MIP+ISO bits Global Muon Trigger e, J, ET, HT, ETmiss 4 m (with MIP/ISO bits) Global Trigger Responsibility of Vienna Institute max. 100 kHz L1 Accept

  6. System Overview Global Trigger + Global Muon Trigger: 1 Rack Drift Tube Track Finder: 3 Racks

  7. Muon Trigger Detectors Drift Tube Chambers and Cathode Strip Chambers are used for precision measurements and for triggering. Resistive Plate Chambers (RPC’s) are dedicated trigger chambers.

  8. Barrel Muon Chambers Mounting of a Drift Tube Chamber into the iron yoke

  9. Endcap Muon Chambers Cathode Strip Chambers on endcap iron yoke

  10. Transport of the First Magnet Coil Module A good muon trigger needs a high magnetic field!

  11. Regional Muon Trigger • Track Finder Processor • Pipeline logic running at 40MHz • (LHC bunch crossing frequency) • Implemented in programmable logic • devices • Based on extrapolation and pattern • matching methods Drift Tubes (CSC’s similar)

  12. Drift Tube Trigger Track Finder Track segment (with direction of extrapolation) Phi Track Finder (Sector Processor) Eta Track Finder The trigger is based on correlating compatible track segments pointing to the vertex. At most four detector planes are used in azimuth (transverse to the magnetic field direction) and three in pseudorapidity (along the beam axis). If possible, track candidates found in both projections are then matched.

  13. Sector Processor Muon Trigger Prototypes Timing Module Wedge Sorter (Bologna) Trigger Crate Eta Track Finder

  14. Global Muon Trigger DR/CSC/RPC: combined in Global Muon Trigger, isolation and MIP information added 252 MIP bits252 Quiet bits 4 m RPC barrel 4 m DT Inputs:8 bit f, 6 bit h, 5 bit pT, 2 bits charge, 3 bit quality,1 bit halo/eta fine-coarse Best 4 m 4 m CSC Output:8 bit f, 6 bit h, 5 bit pT, 2 bits charge/synch, 3 bit quality,MIP bit, Isolation bit 4 m RPC forw.

  15. GMT Option e%|h|<2.1 Rate kHz for 14 GeV OR 98.1 5.4 SMART 97.3 2.9 AND 87.4 2.0 Rates for L=2x1033 cm-2s-1 Optimal combinationhigh efficiency, small rate Global Muon Trigger Efficiencies DT CSC RPC GMT smart Muon Trigger Efficiency GMT OR GMT AND GMT smart • Sophisticated, flexible algorithm • using geometry and quality to achieve: • good efficiency • reasonable rates • ghost suppression GMT Efficiency

  16. Hadron Calorimeter Forward Hadron Calorimeter Barrel Hadron Calorimeter The Global Muon Trigger adds information to muon candidates by correlating them withcalorimeterregions. It confirms muon candidates with MIP information and determines their isolation.

  17. Global Trigger • The trigger decision may be based on simple or more complex criteria, similar to data analysis: • Logic combinations of trigger objects sent by the Global Calorimeter Trigger and the • Global Muon Trigger • Best 4 isolated electrons/photons ET, h, f • Best 4 non-isolated electrons/photonsET, h, f • Best 4 jets in forward regions ET, h, f • Best 4 jets in central region ET, h, f • Best 4 t-Jets ET, h, f • Total ETSET • Total ET of all jets above threshold HT • Missing ETETmissing, f(ETmissing) • 12 jet multiplicities Njets (different ET thresholds and h-regions) • Best 4 muons pT, charge, f, h, quality, MIP, isolation • Thresholds (pT, ET, NJets) • Optional topological and other conditions (geometry, isolation, charge, quality)

  18. Global Trigger Algorithms Object Conditions Logical Combinations 128 flexible algorithms running in parallel are implemented in programmable logic devices. The trigger decision (Level-1-Accept) is a function of the 128 trigger algorithm bits (for physics). 64 more technical algorithms are possible.

  19. Global Trigger Boards Every 25 ns the Global Trigger takes the decision to reject an event or to make it available to the High Level Trigger for further consideration. It consists of the following electronics boards: PSB (Pipelined Synchronizing Buffer) Synchronization of inputs (7 modules) GTL (Global Trigger Logic) Logic (1-2 modules) FDL (Final Decision Logic) Trigger decision (1 module) TCS (Trigger Control System Module) Central trigger control (1 module) L1A (Level-1 Accept Module) Distribution of trigger decision (1 module) TIM (Timing Board) Timing (1 module) GTFE (Global Trigger Frontend) Readout (1 module) PSB (Pipelined Synchronizing Buffer) GTL (Global Trigger Logic)

  20. Trigger Control System and Timing Timing Module Trigger Control System Module The TCS Module controls the data taking based on fast status signals sent by the subsystems. The Timing Module is used for the distribution of the LHC clock.

  21. Physics, Software, Management • Trigger studies (Level-1, High Level Trigger) • Software for testing and operation of the trigger hardware • Coordination of the complete level-1 trigger software • Software for the reconstruction of muons • Preparations for physics analysis, especially with • studies in the field of Supersymmetry • Membership in CMS Management Board • Membership in Editorial Boards for Trigger and • Physics Reconstruction and Selection

  22. Summary The CMS-Trigger Group of the Vienna Institute for High Energy Physics is responsible for the Level-1 Drift Tube Track Finder, the Global Muon Trigger and the Global Trigger and is developing software for triggering. It is working on the reconstruction of muons and is performing studies for physics analysis, in the field of supersymmetry. The current group members are: Scientists (physics, electronics, computer science): J. Erö, M. Jeitler, A. Nentchev, N. Neumeister, P. Porth, H. Rohringer, H. Sakulin, J. Strauss, A. Taurok, C.-E. Wulz Technicians: H. Bergauer, Ch. Deldicque, K. Kastner, M. Padrta Students: M. Galánthay, S. Kostner, B. Neuherz

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