1. 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) 1 2/6/99 L2 ReviewNV/UIC

2. 2/6/99 L2 Review 2 NV/UIC  L2Cal Crate and I/O + Status of L2Cal Algorithms: 4 Jets 4 Electrons 4 Missing E T + Timing of Algorithms + Summary

3. 2/6/99 L2 Review 3 NV/UIC From Calorimeter via FIC/MBT: 10 input cables with 304 Bytes/cable –Header –L1 Seed Tower Bit Masks for EM and Total –L1 Tower E T 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. 2/6/99 L2 Review 4 NV/UIC 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. 2/6/99 L2 Review 5 NV/UIC All L2Cal algorithms will use a low-threshold reference set of L1 0.2x0.2 trigger towers as input for clustering. L1 EM E T - Rounded in 0.25 GeV steps L1 Tot E T - Sum of EM and HAD truncated in 0.5 GeV steps L2Cal Processors jet electron neutrino 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  s???

6. 2/6/99 L2 Review 6 NV/UIC 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 E T of the surrounding 5x5 (or 3x3) tower array Add to Jet list all clusters whose E T sum exceeds a min threshold E T order the Jet list (descending order) Eliminate Jets failing overlap restriction If E T (A) > E T (C) ; keep A,B If E T (C) > E T (A) ; keep C,B

7. 2/6/99 L2 Review 7 NV/UIC W  JJ Data Tower Seed Distributions For a high-E T (>350GeV) jet data sample:  = 20, RMS= 6 for L1(1,2)

8. 2/6/99 L2 Review 8 NV/UIC W  JJ Data L2 Jet Distributions

9. 2/6/99 L2 Review 9 NV/UIC Measured w/ MC - UPG Geant sample Pjet and Cal Jet matching methods: 1) Projection Method 2) Matching Method (run L2Jet algorithm) PJet calorimeter Project PJet axis into calorimeter. Does corresponding seed/cluster E T pass imposed cuts? PJet calorimeter  R<0.5? Compare L2Jets to PJets Look for matches

10. 2/6/99 L2 Review 10 NV/UIC Reference algorithm L1(1,2) L2(1,10) Effs. for seed/cluster cuts and Algorithm(seed cut,cluster cut) L2Jet Efficiency for seeds/clusters Central jets

11. 2/6/99 L2 Review 11 NV/UIC L2Jet Rate Estimates Method: –First weight MC events appropriately 1) use JETRAD to bridge all  PJet Cross Section to central inclusive jet CS in data 2) estimate total MC event cross section for PJet E T >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 E T s

12. 2/6/99 L2 Review 12 NV/UIC 3 = 3x3 algorithm5 = 5x5 algorithm ~ 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-E T jets L1(1,1.5) L1(1,2) L2 thresholds (1,10)(1,8)(1,6)(1,4)(none) 3x3 5x5 L1 only Eff. vs Rate at 20 GeV

13. 2/6/99 L2 Review 13 NV/UIC 3 = 3x3 algorithm5 = 5x5 algorithm Eff. vs Rate at 100 GeV L1(1,7) L1(1,9) order of magnitude rate reduction easily attainable at L2 w/o loss in efficiency no strong cluster size preference L1 only L2 thresholds (1,60)(1,50)(1,40)(1,30)(none)

14. 2/6/99 L2 Review 14 NV/UIC Effects of L1 Total-E T Truncation for 20 GeV Jets L2 (1,4) L2 (1,6) L2 (1,8) L2 (1,10) L2 (1,12) L2 (1,15) L1 (1,2) the effect of L1 energy truncation can be accommodated at L2 by choosing lower jet thresholds 0.25 GeV rounding w/ 0.5 GeV truncation

15. 2/6/99 L2 Review 15 NV/UIC An Example at Lum=1E32 Level-0 45 mb x 1E32 = 4.5 MHz L1(1,9) 6.7 KHz 130 Hz L3 L1(1,12) Eff at 100 GeV ~ 96% ~ 92% 1800 Hz for same Eff

16. 2/6/99 L2 Review 16 NV/UIC The algorithm: Event Samples used in simulations: –Single electrons uniformly distributed in  in the forward region: 1.9<|  |<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 E T Calculate the following summed E T : quantities: 1) E T (EM) of seed tower + largest neighbor 2) E T (Total) of seed tower + largest neighbor 3) sum E T (Total) of 3x3 trigger towers centered on seed tower Order surviving candidates in descending E T (EM) Apply cuts on E T (EM), EM fraction, and Isolation

17. 2/6/99 L2 Review 17 NV/UIC 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 ,  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  x  = 0.3 x 0.3 No rounding/truncation applied to L1 tower energies Courtesy Mrinmoy Bhattacharjee

18. 2/6/99 L2 Review 18 NV/UIC Eff. vs Background Rate at 18 GeV Forward electrons L2 thresholds (1,15)(1,12)(1,10)(none) L1 (1,7) preliminary

19. 2/6/99 L2 Review 19 NV/UIC Eff. vs Background Rate at 18 GeV Forward electrons L2 thresholds (1,17)(1,15)(1,12)(none) L1 (1,10) preliminary

20. 2/6/99 L2 Review 20 NV/UIC Eff. vs Background Rate at 30 GeV Forward electrons L2 thresholds (1,15)(1,12)(1,10)(none) L1 (1,7) preliminary order of magnitude rate reduction attainable at L2 w/ small cost in efficiency w/ FPS match

21. 2/6/99 L2 Review 21 NV/UIC Eff. vs Background Rate at 30 GeV Forward electrons L2 thresholds (1,17)(1,15)(1,12)(none) preliminary L1 (1,10) order of magnitude rate reduction attainable at L2 w/ small cost in efficiency w/ FPS match

22. 2/6/99 L2 Review 22 NV/UIC Candidates will be sorted in descending E T order Information per candidate –eta(1 Byte) –phi(1 Byte) –E T (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. 2/6/99 L2 Review 23 NV/UIC Candidates will be sorted in descending E T order Information per candidate –eta(1 Byte) –phi(1 Byte) –E T (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. 2/6/99 L2 Review 24 NV/UIC Need input from physics groups Information per event –Missing E TX (2 Bytes) –Missing E TY (2 Bytes) –Scalar E T (2 Bytes) –Spare (10 Bytes) Total 16 Bytes/event

25. 2/6/99 L2 Review 25 NV/UIC The algorithm: Possible Enhancements: –Calculate Scalar E T using the same cuts as for Vector E T –Calculate E T for more than one set of Tower cuts –Calculate E T using different threshold for each Tower Loops over all towers within prescribed  range, calculating the vector E T sum of all towers with E T > Min_Tow_E T. It returns the X and Y components of the Missing E T.

26. 2/6/99 L2 Review 26 NV/UIC 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 E T data *Total Tower E T data

27. 2/6/99 L2 Review 27 NV/UIC Time (  s) ~ 2.5 + 1.12 x (# seeds) Average seed range

28. 2/6/99 L2 Review 28 NV/UIC Time (  s) ~ 2 + 2.3 x (# seeds)

29. 2/6/99 L2 Review 29 NV/UIC The average time for 0.5 GeV Tower E T threshold is ~ 33  s All Towers above threshold

30. 2/6/99 L2 Review 30 NV/UIC 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