1. ATLAS ATLAS PESA Meeting 25/04/02 B-Trigger Working Group Work-plan This talk: http://hepunx.rl.ac.uk/atlasuk/simulation/level2/meetings/pesa290502/B-trigger-status.ppt http://hepunx.rl.ac.uk/atlasuk/simulation/level2/meetings/pesa290502/ B-trigger-status.ps http://hepunx.rl.ac.uk/atlasuk/simulation/level2/meetings/pesa290502/ B-trigger-status.pdf John Baines Contents: Updates since the TP (as shown at last meeting) New resource estimates RoI guided B-trigger Future Work Summary

2. ATLAS PESA Meeting 25/04/02 2 Benchmarking & Resource Estimates Note: Most B-trigger resources required for LVL2 full-scan 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  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-2002-013

3. ATLAS PESA Meeting 25/04/02 3 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: http://www.ep.ph.bham.ac.uk/user/atw/bmeet/B-roi-feb02.ppt 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 Ds(  ) 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

4. ATLAS PESA Meeting 25/04/02 4 Future Work Calorimeter RoI guidance for B-triggers: 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 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 - >  X events signal channels : B - > , B->J/  (ee), B - > D s (  (KK)  ) min. bias Addition of pile-up (including pulse history in ECAL). Calibration of ECAL energies (electron work-group) Level-1 studies - Optimisation of thresholds (Level-1 work-group)

5. ATLAS PESA Meeting 25/04/02 5 Future Work – 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

6. ATLAS PESA Meeting 25/04/02 6 Summary A lot of work to do, time-scale very tight (even following postponement of TDR) Priorities are : LVL1 guidance to LVL2 B-trigger: di-muon trigger Low E T Jet Trigger Low E T Electron trigger LVL2 guidance to EF Updates with new geometry. EF selection for B - >  (X) A lot of work is on hold awaiting new data and software. Little incentive for algorithm development whilst framework and interfaces are still evolving. People have drifted away from B-trigger working group to other things. Currently probably less than one Full Time Equivalent working on B-trigger! Need to attract people back by providing: a well defined programme of work a stable set of tools.