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High-Level Trigger Studies Darin Acosta University of Florida DOE/NSF Report on US CMS

High-Level Trigger Studies Darin Acosta University of Florida DOE/NSF Report on US CMS Software and Computing DOE Germantown June 29, 2000. CMS DAQ Architecture. CMS has a multi-tiered trigger system: L1 reduces rate from 40 MHz to 75 kHz

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High-Level Trigger Studies Darin Acosta University of Florida DOE/NSF Report on US CMS

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  1. High-Level Trigger Studies Darin Acosta University of Florida DOE/NSF Report on US CMS Software and Computing DOE Germantown June 29, 2000 DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  2. CMS DAQ Architecture • CMS has a multi-tiered trigger system: • L1 reduces rate from 40 MHz to 75 kHz • Custom hardware processes calorimeter and muon data to select electrons, photons, jets, muons, ETabove threshold • L2, L3,… (HLT) reduces rate from 75 kHz to 100 Hz • Commercial CPU farm runs online programs to select physics channels HLT DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  3. DAQ / HLT Challenge • HLT selection algorithms must keep only 1 event out of 1000 • Limited by ability to filter a L1 data sample which is already rich in physics • DAQ bandwidth is finite • Total event size is 1 MB, event rate is 75 kHz • Bandwidth limited by switch and link technology • First HLT milestone: Demonstrate that L2 can achieve 10X rate reduction using only 25% of the event data • Partial event reconstruction using only calorimeter and muon data DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  4. CMS Physics Groups • Physics Reconstruction and Selection (PRS) groups were established by CMS in 1999: • Electron/Photon C. Seez • Muon U. Gasparini • Jet/Missing ET S. Eno • b/tau A. Caner • Overall coordination by P. Sphicas • Charge is to evaluate the physics capability of CMS from L1 to offline • US-CMS has substantial involvement in the Electron/Photon, Jet/MET and Muon groups • Focus of the Calorimeter, Endcap Muon, and TriDAS construction project communities DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  5. Context of Studies • The L1 Trigger TDR is targeted for November, 2000 • Final design efficiencies and rates being determined • The DAQ TDR is targeted for November, 2001 • Need to understand the rejection capability of theHLT triggers and the amount of data each step requires to validate possible hardware solutions • A Physics TDR is targeted for 2003 • It was delayed to allow for the transition to object-oriented software • In all cases, we need to validate the algorithms for the CMS physics plan, taking into account all possible backgrounds DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  6. HLT History • First HLT milestone was set for November 1999,6 months after the creation of the PRS groups • Despite rapid progress, milestone was not met: • Growing pains: • First wide scale use of ORCA as a tool • Learning curve: • Many inexperienced users and developers tackling C++ • Not enough time: • More validation needed of reconstruction software • Endcap Muon software not completed • HLT algorithms developed only at the last minute • Insufficient manpower and resources • HLT milestone postponed until July 21, 2000 DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  7. Recent Developments • Transition from ORCA3 to ORCA4 • Full migration to Objectivity in place of Zebra files • Additional functionality • Inclusion of endcap muon code (L1 and reconstruction) • Correct handling of out-of-time b.x. in calorimeter • Further validation tests • Production of large simulated event samples • Why? inel = 55 mb and L = 1034 ( 17.3 collisions/b.x.) • GEANT3 production at CERN, Italy, and U.S. (Caltech, UFlorida, UCDavis) • OO hit formatting and digitization done at CERN • 2 weeks for each on a large Linux PC farm • Users access a User Federation • All file/database details hidden from user • Standard ntuples produced for physics groups DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  8. Objectivity Database Objectivity Database ytivitcejbO esabataD ORCA Production 2000 Signal Zebra files with HITS HEPEVT ntuples CMSIM MC Prod. MB Catalog import Objectivity Database ORCA Digitization (merge signal and MB) Objectivity Database ORCA ooHit Formatter ORCA Prod. Catalog import HLT Algorithms New Reconstructed Objects Objectivity Database HLT Grp Databases Mirrored Db’s (US, Russia, Italy..) DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  9. Data Sets • e/ and Jet/MET groups: • 0.9 Mevt (0.8 TB) • Supplement 1999 Monte Carlo production • 0.6 Mevt QCD dijet (various ET ranges) • H bb, H   , SUSY, min. bias pile-up, single particle • Muon group: • 1.3 Mevt (1.3 TB) • Production redone in 2000 to update Pythia, endcap geometry, and event weighting • 0.9 Mevt minimum bias events for rate and pile-up • H ZZ  4 , H WW  2 , W  , Z   , single  • CMS operations: • Expect 1000 TB/year • HLT milestone is a 0.1% Mock Data Challenge! DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  10. Muon Physics Plan • Validate L1 trigger decision and use as a seed for muon reconstruction • Improve PT resolution • Refit with vertex constraint using reconstructed hits • Extrapolate to outer tracker and refit • Apply isolation requirement • Extrapolate to calorimeter and sum energy in cone • U.S. physicists working on L1 and Reconstruction for EMU Muon Rate Effective PT Threshold DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  11. Results: Single  L1 Efficiency First look with ORCA4 Recoverable DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  12. Barrel/Endcap Overlap Region Must include ME2-ME3 tracks for redundancy, despite poor PT resolution Drift Tubes Cathode Strip Chambers We are learning from the simulation… DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  13. e /  and Jet / MET Physics Plan • Electrons: • Bremsstrahlung recovery (>½X0 of silicon tracker) • 0 rejection • Isolation • Track match and E/p cuts (L3) • Jets: • Finer tower granularity • Improved jet axis • Energy calibration (non-linearity, pile-up) • All this improves the ET resolution • MET: • Improve the ET resolution • Taus: • Improve shape cuts DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  14. Jet Resol’n before & after Correction Cone R=0.5 No Pileup Cone R=0.5 Pileup Average for || < 3 DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

  15. Conclusions • Closing in on HLT milestone for L2 performance • Expect results in mid – July • However, this is just a first pass at the code that will eventually run online. Will have to optimize, etc. • The task is challenging and work intensive! • Production is finally complete, analysis is underway • The HLT groups are driving (US)CMS software & computing • Significant work performed by U.S. physicists in Endcap Muon, Jet/MET, and e/ groups • Could use even more manpower, since the “users” are often the code developers as well • User facilities and software/computing support are essential for U.S. physicists to maintain the prominent role taken so far DOE/NSF USCMS Computing and Software Report. HLT Studies D. Acosta

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