ATLAS ATLAS PESA Meeting 20/11/02 B-Trigger Working Group Work-plan This talk: B-trigger-status.ps B-trigger-status.pdf John Baines B-trigger in the TDR: Di-muon triggers Full-scan based triggers RoI guided B-trigger Algorithms & frameworks Summary

ATLAS PESA Meeting 20/11/02 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=2x10 33, 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.

ATLAS PESA Meeting 20/11/02 3 Status of di-muon & full-scan triggers 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 Robustness of selection w.r.t. ID misalignment studied & documented in: ATL-DAQ EF selections documented: Rejection of rate at EF for J/ , D s and B 0 d - >  channels. (Moscow) ATL-DAQ Event Filter Rate for the D s Trigger (Innsbruck) ATL-DAQ 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/  (  ) and B - >  X trigger selections Required c.p.u. resources have been estimated based on measured rates and executions times and documented in: ATL-COM-DAQ Algorithms : LVL2:  Fast (barrel only), Pixel-scan+sctKalman, IDscan, TRT-LUT, xKalmanTRT EF: xKalman, muon-? (for resource calculations assume  Fast re-run at EF) 1) Di-muon trigger at L=2x10 ^33, introducing full scan at lower luminosity

ATLAS PESA Meeting 20/11/02 4 Benchmarking & Resource Estimates 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  Fast Preliminary paper model results (April 2002): Min. Farm size needed at startup Min. size incl. B-physics Difference ~25 c.p.u Final Farm size B-trigger resource estimate: ATL-COM-DAQ LVL2

ATLAS PESA Meeting 20/11/02 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/  (  ) and B - >  triggers using fully simulated events and appropriate LVL2 and EF algorithms. Devise strategy for selecting rare decay channels, B - >  X, at EF Updates full-scan studies using DC1 data.

ATLAS PESA Meeting 20/11/02 6 Using Calorimeter RoI to guide B-physics Triggers Preliminary studies of using low E T 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: EM RoI E T >2 : for J/  (ee) and muon-electron triggers Mean Multiplicity = 1.1 (B - >  X,  p T > 6 GeV) Effic. to tag both e in J/  (e,e) : 80% (e p T >3 GeV) Jet RoI (0.8 x 0.8 cluster) E T >5 : for B(  ) and D s (  ) Mean Multiplicity = 1.7 (B - >  X,  p T > 6 GeV) Efficiency B   p T   4 GeV RoI E T  5 GeV B  D s  p T Ds,   1 GeV RoI E T  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

ATLAS PESA Meeting 20/11/02 7 RoI guided B-trigger 2) RoI guided B-trigger, possibly with addition of full-scan at lower luminosity To do: Measure multiplicities for low E T LVL1 Jet RoI using full simulation (in conjunction with LVL1 group) - essential for TDR Measure multiplicities for low E T LVL1 e/gamma RoI using full simulation(in conjunction with LVL1 group) - essential for TDR Measure efficiencies for low p T e + e - from J/  in conjunction with e/gamma trigger group) Measure trigger rates and efficiencies for B(  ) and B(D s  (KK)  ) signal channels Update resource estimates Current Status: Preliminary studies using fast simulation Rough c.p.u. resource estimates (ATL-COM-DAQ )

ATLAS PESA Meeting 20/11/02 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 - >  X events - done signal channels : B - > , B->J/  (ee), B - > D s (  (KK)  ) - 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

ATLAS PESA Meeting 20/11/02 9 RoI-guided B-trigger – To do (contd.) Verification / optimisation of LVL2 & EF algorithms with latest layout : B-trigger studies including muon trigger: Confirm previous results (Kine muon) Study di-muon trigger – thresholds, rates Requires: New datasets (including pile-up) Algorithms able to read new datasets (LVL2 & EF) Requires: New datasets including muon simulation Muon algorithms available in new framework (LVL2 & EF, barrel & end-cap) Event Filter Selection: Study B - >  (X) selections Study using LVL2 to guide EF Timing measurements for complete chain: Requires: Byte-stream data for all detectors. Convertors for all detectors Optimized algorithms – LVL2 & EF Requires: EF algorithms RoI guidance mechanism for EF

ATLAS PESA Meeting 20/11/02 10 LVL2 Algorithms & Frameworks cTrig: standalone framework using TDR ASCII file input: Pixel-scan, sctKalman, IDscan, TRT-LUT, xKalman-TRT electron-id, B-physics and timing Ntuples truth information For the time being using Offline classes. Will migrate to new EDM as it becomes available Athena using TrigSteerExample1 (currently TDR data only): Pixel-scan, sctKalman, TRT-LUT, xKalman-TRT electron-id, B-physics and timing Ntuples full access to truth information New PESA framework: Work has started on porting TRT-LUT, SiTree, L2Calo, IDscan,  Fast 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! Used for TP - work being discontinued in this framework 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. Aim to move to this framework as soon as possible - but when ?

ATLAS PESA Meeting 20/11/02 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 E T Jet Trigger Low E T Electron trigger LVL2 guidance (RoI) to EF Updates with DC1 data (new geometry). EF selection for B - >  (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 p T electron reconstruction for J/  trigger using “electron vertical slice” Must be in position to enable new people to join work early in new year!