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B-Trigger Working Group Status Report

John Baines. B-Trigger Working Group Status Report. Progress on Algorithms Updates to benchmarking & resource estimates Using Calorimeter information to guide LVL2 B-triggers Summary. This talk: http://hepunx.rl.ac.uk/atlasuk/simulation/level2/meetings/pesa250402/PESA.ppt

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B-Trigger Working Group Status Report

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  1. John Baines B-Trigger Working GroupStatus Report • Progress on Algorithms • Updates to benchmarking & resource estimates • Using Calorimeter information to guide LVL2 B-triggers • Summary This talk: http://hepunx.rl.ac.uk/atlasuk/simulation/level2/meetings/pesa250402/PESA.ppt http://hepunx.rl.ac.uk/atlasuk/simulation/level2/meetings/pesa250402/PESA.ps http://hepunx.rl.ac.uk/atlasuk/simulation/level2/meetings/pesa25040202/PESA.pdf

  2. Progress on Algorithms • IDscan (SCT & Pixels):(Nikos Konstantinidis, Hans Drevermann) • Confirmed that IDscan algorithm:- see Nikos' talk. • Reproduces TP B-trigger performance (10% - 15% better effic. for Ds(fp) trigger) • Gives same performance for reduced layout - 2 instead of 3 barrel Pixel layers • Execution time: • 6 ms scaled to a 4GHz 160 SI95 machine, • 11 ms including Si data preparation • Pixel-scan expected to achieve similar execution time (currently longer) • PixTrig:(Genova) • Currently working to reproduce TP results in Athena framework • Will then modify algorithm to include SCT info. • Plan to look at linear fit in transform space, as used by CDF, as alternative to SiKalman to see if it gives better performance.

  3. Benchmarking & Resource Estimates • Updated resource estimates reported at last ATLAS week • Benchmarking since redone to measure mean, m50 and m95 times for • - full-scan in B->mX events • http://hepunx.rl.ac.uk/atlasuk/simulation/level2/Bphys/bmark.html • - EM RoI Dh x Dp = 0.2 x 0.2 in dijet events with/w.o. pile-up • http://hepunx.rl.ac.uk/atlasuk/simulation/level2/eid/bmark.html • Later used to estimate muon confirmation times. • Parameters and estimates documented in ATLAS note : ATL-COM-DAQ-2002-nnn • Jos has re-run paper model using these parameters as input: • http://www.nikhef.nl/pub/experiments/atlas/daq/paper-para-overview1.pdf

  4. Benchmarking & Resource Estimates Preliminary paper model results (April 2002): Final Farm size Difference ~25 c.p.u Min. size incl. B-physics Min. Farm size needed at startup • Note: • In order to save cpu resources, not using TRT info at LVL2: • => No J/psi(e,e) trigger • Resources required at EF small compared with LVL2 (~few cpu) assuming: • xKalman starting with pixels and guided by Level-2 RoI • (see presentation at previous meeting) • neglecting resources needed for muon reconstruction at EF • Current offline muon algorithms too costly in cpu : • => Only includes muons at LVL2 reconstructed by mFast

  5. Using Calorimeter RoI to guide B-physics Triggers • Preliminary studies of using low ET RoI to define regions to search ID at LVL2(Alan Watson) • Uses fast simulation : • ATLFAST + parameterised calorimeter simulation • Initial results encouraging,see Alan Watson’s talk:http://www.ep.ph.bham.ac.uk/user/atw/bmeet/B-roi-feb02.ppt • EM RoI ET>2 :for J/y(ee) and muon-electron triggers • Mean Multiplicity = 1.1 (B->mX , m pT > 6 GeV) • Effic. to tag both e in J/y(e,e) : 80% (e pT >3 GeV) • Jet RoI (0.8 x 0.8 cluster) ET>5 :for B(pp) and Ds(fp) • Mean Multiplicity = 1.7 (B->mX, m pT > 6 GeV) • Efficiency • B p p • pTp> 4 GeV • RoI ET> 5 GeV • B Dsf • pT Ds, f> 1 GeV • RoI ET> 5 GeV • LVL2 reconstruction inside RoI • potential to save ~factor 10 in execution time c.f. full-scan • but with lower efficiency Actual efficiencies and cpu savings depend on thresholds & multiplicities => need full simulation

  6. Future Work • Calorimeter RoI guidance for B-triggers: Need to confirm results with full simulation. Requires : • Simulation of: • Level-1 EM/Tau trigger algorithm - done (Ed Moyse) • Level-1 Jet trigger algorithm - underway (Ed Moyse) • Level-1 electronics (noise) - who? • Generation of simulated data : • single particles for calibration • B->mX events • signal channels : B->pp, B->J/y(ee), B->Ds(f(KK)p) • min. bias • Addition of pile-up (including pulse history in ECAL). • Calibration of ECAL energies • Level-1 studies - Optimisation of thresholds • B-trigger performance studies • Verification / optimisation of algorithms with latest layout :Requires: • New datasets (including pile-up) • Algorithms able to read new datasets (LVL2 & EF) • B-trigger studies including muon trigger. Requires: • New datasets including muon simulation • Muon algorithms available in new framework (LVL2 & EF)

  7. Summary • Encouraging progress with IDscan algorithm • Converging on a baseline B-trigger strategy minimising resource requirements • Encouraging preliminary results for RoI guided B-trigger at Level-2 • => potential to futher reduce resource requirements, but with reduced efficiency • A lot of work on hold awaiting new data and software : • RoI guided B-physics • inclusion of muon trigger • verification/optimisation of algorithms for latest layout • Timescales tight even with a 6 month delay in the TDR

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