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Sarah Eno U. Maryland

HCAL/JET/MET PRS Group: Status of HCAL software and Higher-level Trigger algorithms/rates for Jets and MET. Sarah Eno U. Maryland. HCAL/JET/MET. Sarah Eno/ Shuichi Kunori Simulation (=GEANT): Sunanda Banerjee (Tata) (+Shashi (Bombay), Shuichi)

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Sarah Eno U. Maryland

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  1. HCAL/JET/MET PRS Group:Status of HCAL software and Higher-level Trigger algorithms/rates for Jets and MET Sarah Eno U. Maryland Sarah Eno, UMD, HCAL MTG at FIT

  2. HCAL/JET/MET • Sarah Eno/ Shuichi Kunori • Simulation (=GEANT):Sunanda Banerjee (Tata) (+Shashi (Bombay), Shuichi) • Calibration and Monitoring:Olga Kodolova (+ Irina, Alexei, Andrei, Victor, Sasha Yershov (all Russians)) • Hcal in ORCA (offline reconstruction code) and interface between Test beam and ORCA:Salavat Abdullin (MD) • Physics Objects & Higher Level Trigger:Sasha Nikitenko (Imperial) (+Pal (Hungary), Isa (Turkey), Mehmet (Turkey), Salavat (MD), Jim Brooke (Bristol), Dan (FNAL), Hans-Peter (CERN), Andrei, Alexei, Irina, Olga, Mikhail, Konstantin, Natasha (Russia) • Plus the Monte Carlo production team at FNAL (Vivian, Hans, Yujun, Greg, Natalie, etc) Sarah Eno, UMD, HCAL MTG at FIT

  3. HCAL/Jet/Met Charge • Shuichi’s talk • Detector simulation • offline calibration/ calibration software • offline detector monitoring • my talk • Detector reconstruction • physics object reconstruction • higher level trigger algorithms and trigger table • test beam software Sarah Eno, UMD, HCAL MTG at FIT

  4. Goals • write code that simulates the HCAL electronics for both the Level1 trigger path, and the DAQ path • find algorithms that optimize the jet resolutions, and write code • find algorithms that optimize the MET resolution, and write code • write code for tau identification using the calorimeter (not tracking) • use code to calculate trigger rates and trigger efficiencies • do timing studies on code for higher level trigger (HLT) Will present current status for each of these items Sarah Eno, UMD, HCAL MTG at FIT

  5. Code to simulate HCAL electronics/DAQ • Vocabulary: • ORCA: offline reconstruction code for CMS • Calorimetry: “package” within ORCA that simulates calorimeter electronics • Calorimetry package managed by Vladimir Litvin (CIT) • HCAL part managed by Salavat Abdullin (UMD) • Goal: have a realistic simulation of the HCAL in time for the Jan 2002 production • Basic code was finished in Sept, incorporated into calorimetry test release in early January. • A few recent improvements • Will be released as part of ORCA 6 (mid-Feb, 2002) Sarah Eno, UMD, HCAL MTG at FIT

  6. Simulate HCAL electronics I’d like to go through this in some detail, to make sure the DAQ people, the detector people, and us have the same understanding… (since this is one of the few times some fraction of the two of us are in the same place) Sarah Eno, UMD, HCAL MTG at FIT

  7. HB/HE Electronics Simulation • start with list of energies deposited in the scintillator and their times(from GEANT) (for “hardscattering”, and for pileup in current crossing and for 5 previous and 3 later crossings) • only 1 depth segment in HB, HE (no separate readout for first scintillator layer). Separate readout for the HO. • convert to mean number of photoelectrons: 1 PE / 0.68 MeV in scintillator in HB (approximately 10 PE/GeV in scint+absorber) and pick actual number according to poisson • pulse shape spreads this number over a little more than 2 beam crossings so the integral of pulse area is number of photo electrons • noise is added, gaussian in E: 2 PE (about 200 MeV) per time sample per readout depth segment, uncorrelated between time buckets • ADC measures pulse once per beam crossing (25 ns intervals) (“time samples”) (LSB is about 3 pe (about 300 MeV)) • pedestal is set in 2nd ADC bin Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  8. HB/HE electronics simulation Shape is convolution of shapes from scintillator & wavelength shifter, HPD, and preamplifier Current best guess? Shape used in code Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  9. HB/HE Electronics Simulation • assume pedestal has been “perfectly” determined by averaging many time sample’s taking during the beam gap • Simple algorithm used to convert time samples to measured eneriges. Just the simple sum of the energies in 2 time samples minus the pedestal times the conversion from PE to MeV (1 PE/0.68 MeV) times a correction for the fraction of energy outside these time samples (1.11) times the sampling correction (147 in HE, 220 in HB, except in towers 16&17) • zero supression is applied to both trigger and DAQ paths (500 MeV threshold). A simple beam-crossing identification is also applied in the DAQ path. Reconstructed energy is “kept” if it is bigger than the energy from the previous and from the next beam crossing. Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  10. HB/HE Electronics Simulation Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  11. HB/HE Simulation • same algorithm is used in level1 path and in DAQ path to extract energy from time samples (except HO is sent as a separate layer to DAQ path, not used in trigger path) Sarah Eno, UMD, HCAL MTG at FIT

  12. Occupancy at high lum (this plot uses the short signal, not the long one) High lum (1034) h=2 h=0 Our current scheme: upsidedown orange triangles Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  13. HF electronics simulation • For HF, similar, except • conversion to PE already done inside GEANT • pulse width assumed small compared to 1 beam crossing time • energy is simply value from one time sample – pedestal • ADC least count is 0.43 pe, noise is 0.125 pe Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  14. Recent Changes to HCAL code HO simulation done “properly”: 1 pe per 0.25 MeV deposited in the scintillator (in HB, this number is 1 pe per 0.68 MeV in the scintillator or 10 pe / GeV in scint+abs) Tower 1 Tower 12 Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  15. Remaining Questions • At the stage of the “timesamples”, need to put data into the test beam/real data format (so code will run on test beam data, and run the same way on test beam/real data and MC) • How do our thresholds affect resolutions? (our simulation of the noise will affect our conclusions… if our noise is too big, low thresholds will be less important. • Should we set the pedestal so we can readout negative as well as positive energies? (right now, set in 2nd bin, so can’t have energies below –450 MeV). DØ does this… (will show reason in 2 transparencies) Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  16. Jet Resolutions versus Thresholds No thresholds s is 0.1531. 2 sigma noise s is 0.1597 Typical jet ETs: 30-50 GeV Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  17. Met Resolutions versus thresholds MET in “Z” events. Should be zero. Conclusion: no reason not to set the zero supression thresholds high Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  18. Jet offsets versus thresholds Hcal “–inf” Efry “–inf” Ebry “-inf” Hcal 0 Efry 0 Ebry 0 Pedestal in 6th bin Set 1: offset is 0.7 Set2: 41.6 Set 3: 16.55 Will these big offsets hurt our Ability to calibrate? Do physics? Hcal 500 MeV Efry 30 MeV Ebry 150 MeV Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  19. Complications Due to Large Offsets Makes it harder to go from jet energy scale corrections to Unclustered MET correction. Part of offset due to noise, part due to Intrinsic offset. Sarah Eno, UMD, HCAL MTG at FIT

  20. Low Luminosity Jet Finding • Have investigated 3 different Jet Finding methods at low luminosity (2e33): • Calorimeter only (for use in higher-level trigger) • Calorimeter + tracking for low PT hadrons: because of our magnetic field, low Pt hadrons bend out of cone. Find these hadrons using tracking and add them back in • Energy flow: goal: ignore HCAL except for neutral hadrons. use tracking for both low PT and high Pt hadrons. Two methods tried • for each track in cone, subtract expected response in calorimeter from calorimeter jet, then add in track • try to match clusters in jet to tracks. If match, remove cluster and add in track Sarah Eno, UMD, HCAL MTG at FIT

  21. Jet Finding for HLT at low lum Still some problems with JES Andrei Krokhotine Sarah Eno, UMD, HCAL MTG at FIT

  22. Calorimeter-only Jet Rates at low lum Calibrated means threshold that is 95% efficient for jets with generator-level Et of this value Andrei Krokhotine Sarah Eno, UMD, HCAL MTG at FIT

  23. Jet-Finding: Step 2 Recover the charged tracks (red) that bend out of the cone Sasha Nikitenko Sarah Eno, UMD, HCAL MTG at FIT

  24. Jet Finding: step 2 Sasha Nikitenko Sarah Eno, UMD, HCAL MTG at FIT

  25. Jets with Tracks: Step 3 Olga & Irina Sarah Eno, UMD, HCAL MTG at FIT

  26. Low Lum Jet Summary 40 GeV 0.5 jet Calorimetry only: Res is 16.5% (or 20% for olga) add out-of-cone tracking 13.1% add in cone tracking 10% Most of improvement comes from adding the out-of-cone tracks. However, can still get more improvement by using all tracks. Sarah Eno, UMD, HCAL MTG at FIT

  27. Jets at High Luminosity Work has been done on this by the Russian groups. However, I won’t talk about that. I’ll show some results by Isa Dumanoglu (Turkey) Goal: algorithms we can use in the higher level trigger to differentiate the “real” jets that come from the hard scattering from fake jets caused from accidental over lay of particles from several pileup events. Doing jets at high luminosity is hard! (average of 17 pileup interactions per trigger) Sarah Eno, UMD, HCAL MTG at FIT

  28. Jets at high luminosity Lesson 1: don’t set your seed and minimum jet Et too low. We started with a seed of 1 GeV and a minimum Et for jet finding of 10 GeV (current defaults in ntuple production) Average of about 55 jets per event. 55 * pi * 0.7^2 = area used up by jets / 10x2xpi = area of calorimeter= 1.3. The whole calorimeter is covered with jets. Particles are shared between multiple jets. Leads to poorly defined jets. Right now, jet finding is done using off an ordered list of seeds. Once a particle is in a jet, it is marked as used, and can not be in other jets. This means particles are usually assigned to the jet with the highest seed (but not always). Sarah Eno, UMD, HCAL MTG at FIT

  29. Jets at High Lum Sample of dijet events, 120<pthat<xxx Delta_r between each jet and its nearest neighbor Sarah Eno, UMD, HCAL MTG at FIT

  30. Jets at High Luminosity Run jet finder on generator-level particles (generator-level jets) Frequency for a generator particle to be within 0.7 of N jets Sarah Eno, UMD, HCAL MTG at FIT

  31. Jets at high luminosity Much better with seed of 2 GeV and minimum jet Et of 20 GeV Why did we set it at 1, 10 to begin with? Because of the way we do the calibration. Can only calibrate jets at about 2-3 s above the jet ET cutoff Sarah Eno, UMD, HCAL MTG at FIT

  32. Jets at high lum Take jets found using generator-level particles, and try after the fact to figure out which particle goes with which jet. Still some ambiguity using current algorithm. Jets are not well defined. Sarah Eno, UMD, HCAL MTG at FIT

  33. Jets at High Lum Dijet sample 120<pthat<xxx Fraction of jet et that comes from pileup particles versus jet et (generator level) Which jets do we want to get rid of? Sarah Eno, UMD, HCAL MTG at FIT

  34. Tau’s Work finished for some time now. Done by Sasha Nikitenko Sarah Eno, UMD, HCAL MTG at FIT

  35. MET • Pal will present more… I just want to show three plots • Have explored two ways to calculate MET (low lum): • Simple vector sum of calorimeter tower • Sum over jets with ET>30, corrected for energy scale, plus over unclustered energy corrected with energy scale correction for 30 GeV Jets (kunori-method) Following plots are all for low luminosity (2e33) Sarah Eno, UMD, HCAL MTG at FIT

  36. MET (A.Nikitenko) before correction after correction Sasha Nikitenko Sarah Eno, UMD, HCAL MTG at FIT

  37. MET (SUSY plot looks similar) (“kunori”) (“raw”) While method 2 is better to use for mass calculations, etc, does not seem to provide better signal/background for trigger Pal Hidas Sarah Eno, UMD, HCAL MTG at FIT

  38. MET “kunori-type” MET rate at low Lum (2e33), “corrected” for GEANT bugs Very challenging! Needs complicated weighting scheme As Pal will explain, MET rate is very sensitive to any bug in GEANT, no matter how rare… Simple L3 MET trigger at 120 GeV gives 1 Hz Pal Hidas Sarah Eno, UMD, HCAL MTG at FIT

  39. SUSY Post LEP SUSY benchmarks (DeRoeck et al) Sarah Eno, UMD, HCAL MTG at FIT

  40. SUSY Sarah Eno, UMD, HCAL MTG at FIT

  41. SUSY “point 1” MET+1 jet MET+2 jets For different jet thresholds, vary MET cut. Want to maximize efficiency while minimizing rate. So, lower right hand corner is good. For a rate of 1 Hz, any of these triggers gives a maximum efficiency of about 55%. MET by itself as good as MET+jet triggers Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  42. For Fun, see how could we could do How to optimize different signals at once? Use a Monte Carlo technique called a “genetics” algorithm. Start with vectors of cuts. Allow them to “breed”. Select offspring to live that maximize some selection criteria. Allow “mutations” in offspring as well. Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  43. By adding lots of triggers, can get efficiency up a little (55.864.1%)… but we have to think about what we think is best, given the fact we don’t know which point nature will chose. I’d go for the low MET threshold. Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  44. Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  45. MET Likes MET and MET+4 jets in general. Perhaps, for susy, MET+1 or 2 jets less important Maybe set high band width for these… Sarah Eno, UMD, HCAL MTG at FIT

  46. Next milestone High luminosity rates and algorithms Raw data format Timing tests Calibration document Will not meet second two (except, second for taus). Shuichi will tell status of third Sarah Eno, UMD, HCAL MTG at FIT

  47. Timing Studies Nobody manpower Need to estimate time to unpack data, to run algorithms Sarah Eno, UMD, HCAL MTG at FIT

  48. seeds Lowest threshold considered so far is 30 GeV in trigger Salavat Abdullin Sarah Eno, UMD, HCAL MTG at FIT

  49. Future • first pass results for low lum almost finished • Still waiting for ntuples with proper branson weights • met rate calculation suffers from GEANT bugs • just began large high luminosity production • are all the GEANT bugs out? • still need work on low ET jets, especially at high lum • need timing tests • need raw data format Sarah Eno, UMD, HCAL MTG at FIT

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