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Nikos Varelas University of Illinois at Chicago L2Cal Group at UIC: Mark Adams Bob Hirosky

L2Cal. Review. (Algorithms). Nikos Varelas University of Illinois at Chicago L2Cal Group at UIC: Mark Adams Bob Hirosky Rob Martin Nikos Varelas Marc Buehler (graduate student) James Heinmiller (undergraduate) Mike Klawitter (part time engineer). 2/6/99. 1. L2 Review. NV/UIC.

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Nikos Varelas University of Illinois at Chicago L2Cal Group at UIC: Mark Adams Bob Hirosky

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  1. L2Cal Review (Algorithms) Nikos Varelas University of Illinois at Chicago L2Cal Group at UIC: Mark Adams Bob Hirosky Rob Martin Nikos Varelas Marc Buehler (graduate student) James Heinmiller (undergraduate) Mike Klawitter (part time engineer) 2/6/99 1 L2 Review NV/UIC

  2. Overview • L2Cal Crate and I/O • Status of L2Cal Algorithms: • Jets • Electrons • Missing ET • Timing of Algorithms • Summary

  3. L2Cal Inputs • From Calorimeter via FIC/MBT: 10 input cables with 304 Bytes/cable • Header • L1 Seed Tower Bit Masks for EM and Total • L1 Tower ET data for EM and Total • From SCL via MBT: • L1 accept (3 Bytes) • L1 Qualifiers (2 Bytes) • L2Jet Needed • L2Em Needed • L2Etmiss Needed • 3 Spare Bits • Unbiased Sample • Forced Write • Collect Status • L2Global accepts

  4. L2Cal Outputs • To L3 • For normal events send the L2Global output • For UBS or Forced Write events the full L1 input and L2Cal output will be sent • To L2Global • About 136 Bytes/event (including headers) • Will be fine tuned when algorithms are finalized based on input from physics/Id groups • Each worker will preface its data with a 12Byte header • Header will include information about the processing status (i.e., format errors, timeouts etc) of the event • Each worker will complete transmission with a 4 Byte trailer

  5. L2Cal Processors jet electron neutrino L2Cal Algorithms All L2Cal algorithms will use a low-threshold reference set of L1 0.2x0.2 trigger towers as input for clustering. L1 EM ET - Rounded in 0.25 GeV steps L1 Tot ET - Sum of EM and HAD truncated in 0.5 GeV steps What are the efficiencies of these algorithms? Can we reduce the trigger rate w/o significant cost in efficiency? Can we do all these stuff in less than 100 ms???

  6. L2 Jets • The algorithm: • Event Samples used in simulations: • Data: W-> JJ triggers from Run 1C Global Runs with Lum = 17E30 • MC: UPG GEANT inclusive jet events w/ generated thresholds: (2,5,10,20,40,80 GeV) overlapped with: (1,3,5,7) additional MB interactions (not overlapped with noise) • Start w/ list of jet seed towers from L1 • For each seed tower, cluster ET of the surrounding 5x5 (or 3x3) tower array • Add to Jet list all clusters whose ET sum exceeds a min threshold • ET order the Jet list (descending order) • Eliminate Jets failing overlap restriction If ET(A) > ET(C) ; keep A,B If ET(C) > ET(A) ; keep C,B

  7. W->JJ DataTower Seed Distributions For a high-ET (>350GeV) jet data sample: m = 20, RMS= 6for L1(1,2)

  8. W->JJ DataL2 Jet Distributions

  9. calorimeter PJet calorimeter PJet DR<0.5? L2Jet Efficiency and Rate Studies Measured w/ MC - UPG Geant sample Pjet and Cal Jet matching methods: 1) Projection Method Project PJet axis into calorimeter. Does corresponding seed/cluster ET pass imposed cuts? 2) Matching Method (run L2Jet algorithm) Compare L2Jets to PJets Look for matches

  10. L2Jet Efficiency for seeds/clusters Reference algorithm L1(1,2) L2(1,10) Central jets Effs. for seed/cluster cuts and Algorithm(seed cut,cluster cut)

  11. L2Jet Rate Estimates • Method: • First weight MC events appropriately 1) use JETRAD to bridge all h PJet Cross Section to central inclusive jet CS in data 2) estimate total MC event cross section for PJet ET>5 GeV; ~ 1/11 Min Bias cross section • Calculate trigger rate as ~ fraction of MB events passing imposed threshold(s) • Plot L2Jet Efficiency vs Rate for 20 and 100 GeV PJets. • Compare L2 3x3 jet algorithm to 5x5 version • Measure Eff. vs Rate w/ and w/o L2 clustering • Examine the effects of 0.5 GeV truncation to trigger-tower ETs

  12. 3 = 3x3 algorithm 5 = 5x5 algorithm L2 thresholds (1,10)(1,8)(1,6)(1,4)(none) 5x5 L1(1,1.5) 3x3 L1(1,2) L1 only Eff. vs Rate at 20 GeV • ~ factor of 3 rate reduction w/ 20% eff. cost • no strong cluster size preference • need to tune the MC further so we can study/improve • the algorithm for low-ET jets

  13. 3 = 3x3 algorithm 5 = 5x5 algorithm Eff. vs Rate at 100 GeV L2 thresholds (1,60)(1,50)(1,40)(1,30)(none) L1(1,7) L1(1,9) L1 only • order of magnitude rate reduction easily attainable • at L2 w/o loss in efficiency • no strong cluster size preference

  14. Effects of L1 Total-ET Truncation for 20 GeV Jets L2 (1,4) w/ 0.5 GeV truncation L1 (1,2) L2 (1,8) L2 (1,6) L2 (1,10) 0.25 GeV rounding L2 (1,12) L2 (1,15) the effect of L1 energy truncation can be accommodated at L2 by choosing lower jet thresholds

  15. L2Jet Rejection An Example at Lum=1E32 Level-0 Eff at 100 GeV 45 mb x 1E32 = 4.5 MHz L1(1,9) ~ 96% 6.7 KHz L1(1,12) <L2(1,30)> ~ 92% 130 Hz 1800 Hz for same Eff L3

  16. L2 Electrons • The algorithm: • Event Samples used in simulations: • Single electrons uniformly distributed in f, in the forward region: 1.9<|h|<2.3 • ISAJET dijet events with various thresholds starting at 2 GeV Events were processed through UPG_GEANT with two (on average) additional interactions (not overlapped with noise) • Start w/ list of EM seed towers from L1 • For each seed tower, determine nearest neighbor w/ the largest ET • Calculate the following summed ET : quantities: • 1) ET(EM) of seed tower + largest neighbor • 2) ET(Total) of seed tower + largest neighbor • 3) sum ET(Total) of 3x3 trigger towers centered on seed tower • Order surviving candidates in descending ET(EM) Apply cuts on ET(EM), EM fraction, and Isolation

  17. L2 Electrons: Efficiency and Rate Studies Courtesy Mrinmoy Bhattacharjee • L1 Cuts: • FPS: 0.3 MIPs (upstream) 5 MIPs (downstream) U view matching V view matching • CAL: EM trigger tower above threshold • Match FPS with CAL L1 Tower in Quadrant • L2 Cuts: • FPS: Require downstream U and V view matching -> convert to h, f in 0.2 x 0.2 bins • CAL: Find EM cluster using NN algorithm. Apply EM fraction and Isolation cuts. • Match FPS track to EM cluster within Df x Dh = 0.3 x 0.3 • No rounding/truncation applied to L1 tower energies

  18. Forward electrons Eff. vs Background Rate at 18 GeV preliminary L2 thresholds (1,15)(1,12)(1,10)(none) L1 (1,7) L1 (1,7)

  19. Forward electrons Eff. vs Background Rate at 18 GeV preliminary L2 thresholds (1,17)(1,15)(1,12)(none) L1 (1,10) L1 (1,10)

  20. Forward electrons Eff. vs Background Rate at 30 GeV preliminary L2 thresholds (1,15)(1,12)(1,10)(none) L1 (1,7) L1 (1,7) w/ FPS match order of magnitude rate reduction attainable at L2 w/ small cost in efficiency

  21. Forward electrons Eff. vs Background Rate at 30 GeV preliminary L2 thresholds (1,17)(1,15)(1,12)(none) L1 (1,10) L1 (1,10) w/ FPS match order of magnitude rate reduction attainable at L2 w/ small cost in efficiency

  22. L2Jet Output • Candidates will be sorted in descending ET order • Information per candidate • eta (1 Byte) • phi (1 Byte) • ET (2 Bytes) • eta center (1 Byte) • phi center (1 Byte) • eta leading TT (1 Byte) • phi leading TT (1 Byte) • Spare (4 Bytes) • Total 12 Bytes/object

  23. L2Em Output • Candidates will be sorted in descending ET order • Information per candidate • eta (1 Byte) • phi (1 Byte) • ET (2 Bytes) • EM fraction (1 Byte) • Isolation Fraction (1 Byte) • eta leading TT (1 Byte) • phi leading TT (1 Byte) • eta other TT (1 Byte) • phi other TT (1 Byte) • Spare (2 Bytes) • Total 12 Bytes/object

  24. L2Etmiss Output • Need input from physics groups • Information per event • Missing ETX (2 Bytes) • Missing ETY (2 Bytes) • Scalar ET (2 Bytes) • Spare (10 Bytes) • Total 16 Bytes/event

  25. L2Etmiss • The algorithm: • Possible Enhancements: • Calculate Scalar ET using the same cuts as for Vector ET • Calculate ET for more than one set of Tower cuts • Calculate ET using different threshold for each Tower Loops over all towers within prescribed h range, calculating the vector ET sum of all towers with ET > Min_Tow_ET. It returns the X and Y components of the Missing ET.

  26. L2Cal Algorithm Timing • Code: • written in C • compiled with C or C++ compiler on DEC Alpha workstation running UNIX (timing results roughly the same) • Executable down-loaded and run on UIC PC164 evaluation board containing DEC 21164 Alpha processor with 500MHz clock • Event Sample: • MC Dijet data generated with ISAJET • Data block Structure as planned for hardware • 10 “cable blocks” containing: • EM Tower Seed Mask • Total Tower Seed Mask • EM Tower ET data • Total Tower ET data

  27. L2Jet Algorithm Timing Average seed range Time (ms) ~ 2.5 + 1.12 x (# seeds)

  28. L2Em Algorithm Timing Time (ms) ~ 2 + 2.3 x (# seeds)

  29. L2Etmiss Algorithm Timing The average time for 0.5 GeV Tower ET threshold is ~ 33 ms All Towers above threshold

  30. Summary • We have a fully designed L2Cal Preprocessor system which has sufficient CPU power to execute reasonable L2 algorithms with < few % deadtime • if more power needed, can add up to two Workers for parallel processing • We have working versions of Jets/Electron/Missing ET algorithms which offer acceptable rate reduction • The data movement architecture is complete and the monitoring path has been established (see previous talks) • We request TDR approval

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