1. John Baines B-Trigger Working GroupWork-plan • B-trigger in the TDR: • Di-muon triggers • Full-scan based triggers • RoI guided B-trigger • Algorithms & frameworks • Summary This talk: http://hepunx.rl.ac.uk/atlasuk/simulation/level2/meetings/pesa201102/B-trigger-status.ppt http://hepunx.rl.ac.uk/atlasuk/simulation/level2/meetings/pesa201102/ B-trigger-status.ps http://hepunx.rl.ac.uk/atlasuk/simulation/level2/meetings/pesa201102/ B-trigger-status.pdf

2. B-Physics Trigger in the TDR • Demonstrate viable & affordable B-physics trigger based on the evaluation of two strategies: • 1) Di-muon trigger at L=2x1033, introducing full scan at lower luminosity • 2) RoI guided B-trigger, possibly with addition of full-scan at lower luminosity • To do this need measurements of: • Efficiency for signal channels • Rate • c.p.u resource estimate based on test-bed measurements for whole chain.

3. Status of di-muon & full-scan triggers 1) Di-muon trigger at L=2x10^33, introducing full scan at lower luminosity • Current Status: • Full-scan based strategy studied in detail using fully-simulated events and appropriate LVL2 and EF algorithms and documented in TP back-up document: ATL-DAQ-2000-031 • Robustness of selection w.r.t. ID misalignment studied & documented in: ATL-DAQ-2001-006 • EF selections documented: • Rejection of rate at EF for J/Y, Ds and B0d->pp channels. (Moscow) ATL-DAQ-2000-017 • Event Filter Rate for the Ds Trigger (Innsbruck) ATL-DAQ-2001-003 • Impact of only having 2 pixel layers at start-up studied using IDscan LVL2 algorithm • Estimates exist for LVL1 di-muon rates and EF rates after J/Y(m,m) and B->mmX trigger selections • Required c.p.u. resources have been estimated based on measured rates and executions times and documented in: ATL-COM-DAQ-2002-013 • Algorithms : • LVL2: mFast (barrel only), Pixel-scan+sctKalman, IDscan, TRT-LUT, xKalmanTRT • EF: xKalman, muon-? (for resource calculations assume mFast re-run at EF)

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 LVL2 • Note: • Based on custom-LVL2 algorithms, light-weight EDM, excludes data access overheads • Most B-trigger resources required for LVL2 full-scan • In order to save cpu resources, estimate does not include TRT at LVL2: • => No J/psi(e,e) trigger • EF • Resources required at EF small compared with LVL2 (~few cpu) assuming: • xKalman starting with pixels and guided by Level-2 RoI • neglecting resources needed for muon reconstruction at EF • Current offline muon algorithms too costly in cpu : • => Only includes muons at LVL2 reconstructed by mFast B-trigger resource estimate: ATL-COM-DAQ-2002-013

5. To do: di-muon & full-scan triggers 1) Di-muon trigger at L=2x10^33, introducing full scan at lower luminosity • To do: • Update di-muon trigger rates based on full simulation of signal and background (in conjunction with muon trigger group) - essential for TDR • Move LVL2 and EF algorithms to new selection framework - essential for TDR • Update resource estimates based on test-bed measurements using new selection framework and including conversion from byte-stream - essential for TDR • Measure trigger rates and trigger selection efficiencies for J/Y(m,m) and B->mm triggers using fully simulated events and appropriate LVL2 and EF algorithms. • Devise strategy for selecting rare decay channels, B->mmX, at EF • Updates full-scan studies using DC1 data.

6. 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

7. RoI guided B-trigger 2) RoI guided B-trigger, possibly with addition of full-scan at lower luminosity • Current Status: • Preliminary studies using fast simulation • Rough c.p.u. resource estimates (ATL-COM-DAQ-2002-013) • To do: • Measure multiplicities for low ET LVL1 Jet RoI using full simulation (in conjunction with LVL1 group) - essential for TDR • Measure multiplicities for low ET LVL1 e/gamma RoI using full simulation(in conjunction with LVL1 group) - essential for TDR • Measure efficiencies for low pT e+e- from J/Y (in conjunction with e/gamma trigger group) • Measure trigger rates and efficiencies for B(pp) and B(Dsf(KK)p) signal channels • Update resource estimates

8. RoI Guided B-trigger - To do • In RoI guided scheme, the main factors driving resource requirements are: • muon trigger rate & muon algorithm time • Jet RoI multiplicity, Jet RoI Size, time for ID reconstruction in Jet RoI • => Important to confirm RoI multiplicities with full simulation • => Need full simulation to determine trigger efficiency for signal channels • Requires : • Simulation of: • Level-1 EM/Tau trigger algorithm - done (Ed Moyse) • Level-1 Jet trigger algorithm - done (Ed Moyse) • Level-1 electronics (noise) - status? • Generation of simulated data : • single particles for calibration - done • B->mX events - done • signal channels : B->pp, B->J/y(ee), B->Ds(f(KK)p) - done • min. bias - done • Addition of pile-up (including pulse history in ECAL). - in progress • Calibration of ECAL energies (e/gamma work-group) - in progress • Level-1 studies - Optimisation of thresholds (Level-1 work-group) - in progress

9. RoI-guided B-trigger – To do (contd.) • Requires: • New datasets (including pile-up) • Algorithms able to read new datasets (LVL2 & EF) Verification / optimisation of LVL2 & EF algorithms with latest layout : Timing measurements for complete chain: • Requires: • Byte-stream data for all detectors. • Convertors for all detectors • Optimized algorithms – LVL2 & EF • B-trigger studies including muon trigger: • Confirm previous results (Kine muon) • Study di-muon trigger – thresholds, rates • Requires: • New datasets including muon simulation • Muon algorithms available in new framework (LVL2 & EF, barrel & end-cap) • Event Filter Selection: • Study B->mm(X) selections • Study using LVL2 to guide EF • Requires: • EF algorithms • RoI guidance mechanism for EF

10. LVL2 Algorithms & Frameworks • cTrig: standalone framework using TDR ASCII file input: • http://hepunx.rl.ac.uk/atlasuk/simulation/level2/doc/ctrigCVS/ • Pixel-scan, sctKalman, IDscan, TRT-LUT, xKalman-TRT • electron-id, B-physics and timing Ntuples • truth information Used for TP - work being discontinued in this framework • Athena using TrigSteerExample1 (currently TDR data only): • http://hepunx.rl.ac.uk/atlasuk/simulation/level2/doc/Prototypes/TrigSteerExample1/ • Pixel-scan, sctKalman, TRT-LUT, xKalman-TRT • electron-id, B-physics and timing Ntuples • full access to truth information For the time being using Offline classes. Will migrate to new EDM as it becomes available Developed as prototype - direct port of cTrig algorithms and simple EDM to athena. Has not been used for trigger studies; but in principle could be. • New PESA framework: • Work has started on porting TRT-LUT, SiTree, L2Calo, IDscan, mFast • Working chain expected for Trigger release 6 - Feb 2003 • Full access to truth information (navigation from track to truth) is essential - must make sure this is delivered! Aim to move to this framework as soon as possible - but when ?

11. Summary • A lot of work to do, time-scale very tight. Priorities are : • LVL1 guidance (RoI) to LVL2 B-trigger: • di-muon trigger • Low ET Jet Trigger • Low ET Electron trigger • LVL2 guidance (RoI) to EF • Updates with DC1 data (new geometry). • EF selection for B->mm(X) • A lot of work is still on hold awaiting new data and software. • PESA core s/w still evolving fast. Need stable environment (releases, examples) to enable algorithm development to restart. • People have drifted away from B-trigger working group to other things • Current work is taking place within other working groups: • muon trigger • LVL1 validation • porting of algorithms to new framework • Need to attract people back by providing: • a well defined programme of work • a stable set of tools complete with examples and basic documentation. • A first step: low pT electron reconstruction for J/Y trigger using “electron vertical slice” • Must be in position to enable new people to join work early in new year!