Summary from Ringberg ID workshop

1. Summary from Ringberg ID workshop • Not a straightforward summary of all the Ringberg talks - try to draw out messages and things for follow-up • Cannot mention everything - sorry if your talk / favourite subject not mentioned! • No attributions - everything is taken from the workshop • See the workshop slides for more information • http://indico.cern.ch/conferenceDisplay.py?confId=23706 • Progress - some of the Ringberg highlights • Integration and robustness • Resources • Choices and complexity • Getting ready for data Richard Hawkings (CERN) ATLAS CAT physics meeting, 9/5/08 Richard Hawkings

2. Progress - Tracking software • Complete ‘NewTracking’ chain in place • Good performance in general • Work still ongoing in dense jets (cf b-tag) • CPU under control (4 sec/event) • But need to tune for pileup • One output track collection produced • Simple for track consumers • All options integrated (incl. DQ and perfmon) in InDetRecExample • Very modular - plug-and-play (e.g. fitters) • New appl in low-pT tracking (<500 MeV) • Optional additional pass after standard tracking, to pick up unused hits • Particularly important for min-bias studies • Still some issues before startup • Handling broad/split/flipped RIOs • Tuning, robustness, optimisation • EDM issues (later) Low pT efficiency Low pT fake rate Richard Hawkings

3. Progress - cosmic reconstruction • ID software chain reconstructing cosmics! • Combined tracks in SCT, TRT and muons • Standard tracking chain + dedicated cosmic tracking • Many lessons learned … • Realism: dead/noisy modules: so far by hand! • Effects due to ‘strange’ geometry - glancing tracks, odd angles • Pathological events - many seeds, high multipcty • Alignment is good enough to find tracks! • Need to understand overlap between track algs • Only 1/3 tracks found by both tracking chains • Preparation for next activities • Cosmics with magnetic field and pixels • Single beam: halo and beam-gas Track classes Richard Hawkings

4. Progress - bytestream and trigger • Simplification and (offline) speed-up of bytestream converters • Allows use of same code at LVL2 and EF/offline • Code developed in MIG2 - ready, need muons • HLT tracking software participating in both Mx cosmic and TDAQ technical runs • Algorithms adapted for high cosmic efficiency • Pre-recorded events to test dataflow, rates, etc • MC studies with release 14 … • Exploring effects of different track fitters in EF • Comparisons of LVL2 and EF track efficiency • Comparisons of EF/offline M6 cosmic Richard Hawkings

5. Progress - conversions, V0 and material • Tracking framework now quite mature, algorithms to maximise efficiency • Forward tracking seeded from Si, then backtracking from TRT, standalone TRT, TRT + single Si space point • All in coherent framework, ready for analysis • Algorithms to find conversions and V0s • A lot of commonality - can they be merged? • Effort starting on mapping ID material via ee Conversion rvtx resolution • Using 0 in min bias events • Enough statistics in a few months • Challenges ahead … • Normalisation (use beampipe?) • Efficiency determination • Various ideas - exploit Ks, isospin • Exploit particle ID and calo info • Cuts to improve purity/resolution Richard Hawkings

6. Progress - muon reconstruction • Long effort to provide common tracking framework for ID and muons, bearing fruit • MooreMuId performance good in release 14 • Small fake rate even with cavern background • Use of common tracking framework naturally supports global track fits - important to get best tracking resolution • ID dominates resolution up to ~ 50 GeV! • Bewildering array of muon reco packages • Standalone, +ID, +calo, seeded from MS/ID • Modular approach important - try to combine the best features of each rather than choosing between two monolithic chains • Explore tag/probe efficiency with ,,Z • One muon identified in ID+MS, second in MS, search for corresponding ID track • Interesting possibility to adapt b-tag System8 J/, pT>4 GeV Z , ID/MS track fit Richard Hawkings

7. Progress - alignment on Monte Carlo • CSC exercise very valuable for alignment group • Data with initial (unrealistically) large misalignments - can ‘bootstrap’ and align silicon and TRT in a consistent way • Reality check - strategies and implementation work - although event sample (multimuons) is unrealistic • Many lessons learned, e.g. followup weak modes • New work: 3x3 distortion ‘matrix’, effect on ID perf • Some issues remain - Z width ‘mystery’ • Followup with FDR1 • Semi-realistic single track alignment stream • Time pressure for fast turnaround - CAF-like computing infrastructure (though I/O problems) • ‘Reasonable’ alignment constants produced • Again, many lessons learned - need realistic starting point, auxiliary event samples, how to run computing • FDR2 comes next - with full CAF setup Richard Hawkings

8. Progress - alignment with real data • SR1 cosmic runs already given first idea of internal alignments of different parts (barrel, endcaps) with ~100k cosmic tracks • First runs in pit (M-ID, M6) have low statistics O(10k tracks), but do not show big differences to alignment corrections in SR1 TRT M6 SCT M6 • Also gathering all survey data on ID parts • Big effort made surveying modules, barrels, disks • How to use this optimally in track-based alignment? • Need to complete DB upload, error treatment • Overall ID installation surveyed to 0.1-0.3 mm • Relatively good shape to start track alignment Richard Hawkings

9. Progress - FSI system • Laser interferometry system for SCT • Measure grid lengths to 1m over 1m • 852 grid lines inside SCT volume - build up 3D picture of how SCT structures move • Potentially, scan every ~ 10 minutes • Hardware commissioning well advanced • Very impressive optical system in SR1 • First results for some grid lines • To be improved with full laser commissioning • How to use it and incorporate into alignment • Need full analysis software to routinely perform scans, convert to geometrical profile of SCT movements, validate results • Combination with track alignment - define stable periods? apply short term corrections? • Need experience with real SCT motions • How to relate to integrated ID alignment including pixels and TRT which have no FSI? One line, 20 mins Richard Hawkings

10. Integration - conditions data • Lots of conditions data written online • Configuration information from DAQ • Calibration information from online calib • DCS data (to offline COOL) • Need to start using this in offline reconn • Optimal parameters for reconstruction • Knowledge of dead/noisy modules • Essential to have this working for startup • Online/offline consistency checks • Still requires a lot of work • Make sure data is written routinely online • Make it available in Athena to all clients • In an integrated way - e.g. ISCT_Conditions • Using the standard DB tools (IOVDbSvc) • Database access issues for real data • Available from Oracle at CERN/T1 • More difficult beyond T1s (some ideas…) Richard Hawkings

11. Integration - prompt calibration and alignment Discussion with beer • Prompt cal/align in 24h is extremely challenging • Need to integrate Si alignment, TRT calibration, TRT alignment, beamspot finding in one process • Using ID calib stream and perhaps express/cosmics • Start of discussions about how to do this … • FDR1 was first instructive attempt … • Si and TRT alignment only, offsite computing • Spur to develop ‘control framework’ to manage iterations - needs to be further enhanced • Needs O(50 CPUs) and associated I/O and storage to complete in 24hours - big computing system • Next priorities • Fully integrate TRT calibration and alignment • Beamspot-finding, interplay with alignment • Use of cosmics and perhaps express stream data • … Very challenging to be ready for FDR2 • Is 24h turnaround realistic for 1st data…? Sober design Richard Hawkings

12. Robustness • Expect the unexpected - as in M6 • Beware highly combinatoric algorithms, guard against unreasonably high occupancy • Need full conditions data chain to be working • Mask noisy modules - inform reconstruction of dead ones, so track scoring etc is aware • Might well have dead areas in silicon due to cooling problems • Hopefully all detectors will be working at some level from startup (they are all installed) • An optimist said: ‘If we get it working at all, it will take a lot to kill it’ … • A pessimist said: ‘The SCT barrel is a sad story, as you know’ • We have a good ‘toolkit’ of modular tracking software just in case major parts are not working • Robustness in Tier-0 reconstruction • Keep going if at all possible - proper use of error & return codes etc Noisy SCT modules Hadronic shower in TRT Richard Hawkings This will never happen - will it?

13. Resources - event sizes Full ATLAS AOD: • Global ATLAS problem for AOD/ESD size • AOD in release 14.0.0 was 860 kB • Increased dramatically just as release closed • Since reduced by factor ~2 with crash effort • AOD too big - fewer events on disk, multiply access problems, reduce processing speed • ID is a significant part of ESD and AOD • Technical tricks (double to float), bit packing • Make sure every bit counts, avoid overheads • Think carefully what really needs to be stored • Flexibility - tailor content to particle type - e.g. store more for tracks ID-d as leptons • Pileup is lurking around the corner… • Big effect e.g. on vertexing EDM - optimisation will be required … • Depending on LHC strategy, we may have significant pileup very soon ID alone: Vertex EDM: Richard Hawkings

14. Resources - simulation • FATRAS fast tracking simulation now mature • Good reuse of existing Tracking components • Geometry, extrapolators; interactions using G4 modules or parameterisation (nuclear interactions) • Fast track simulation, with optional full recon • Now integrating more and more parts of Digitisation model for added realism • Impressive validation results • Better than AtlFast I (parameterisation), faster than G4 fullsim (which is used by AtlFast II) • Also becoming usable for muon tracking • ATLAS simulation crisis • CPU time x 4-5 too big (with latest G4 models), event size x3 too big for computing model • NB - already expecting to simulate only 20% data • FATRAS (+ shower libs) could be part of solution • Need to make simulation community aware • Be prepared to tune FATRAS with full data • Still need for G4 for some studies, optimise balance G4+recon efficiency Richard Hawkings

15. Resources - calibration model • ID Calibration plans becoming clearer • Calibrations to be done at ROD level, between fills: All detectors have tasks • Calibration in the CAF • TRT Rt/t0 calibration, e/pi sep, pixel Lorentz angle, depletion depth, charge sharing, alignment of ID parts and integrated ID alignment, beamspot, … • Up to O(100 CPUs) making use of calibration and express streams at CAF • Need better definition/separation of monitoring and calibration tasks • Concentrate CAF on things which can be improved in the ~24h before bulk reco • Other tasks might be better done as monitoring in Tier-0, or even in RODs (pixel map?) • Offline is ‘easier’ than online, but CAF/Tier-0 is quasi-online - cannot fall behind • Don’t forget calibration for reprocessing - at Tier-1,2, institutes … • This is a big system - all requests use scarce resources (CPU, disk, I/O) and need to be well-justified and matched to available resources • Also consider optimal ordering, what in parallel • Flexibility to adapt to stability of real data Richard Hawkings

16. Choices and optimisation • In many areas, blessed with N alternatives • Vertexing algorithms, track fitters, pattern recognition strategies, muon reconstruction • Obvious benefits, but also drawbacks • Multiplication of effort (develop, validate, maintain, understand/use downstream) • CPU, memory and event size penalties • Probably the most critical at present… • Delicate balance between the two, but time to ‘baseline’ whilst keeping other options open • Favour ‘simple and straightforward’ ? • Once we see real data, criteria may change! • To achieve this, important to have • Common interfaces / EDM wherever possible • Ability to compare apples and apples • Feedback from the clients - performance groups • Many examples (also from trigger, e.g. EF fitters) Tau recon Tracks in jets (b-tag) 2ndary vertex Richard Hawkings

17. EDM - ‘break-down of factorisation’ • For practical reasons, recon/EDM is ‘linear’ • PRDs track/vertexcomb perfanalysis • Examples of ‘pushing the limits’ due to real physics needs - getting the most from ATLAS • Broad/split/flipped ROT/clusters indicated by tracking • Discussions - solution in sight for 14.2.0 • Kinematic fitting: B-physics and high pT physics • Support ‘extended’ track parameters with vertex / mass / error matrix in tracking EDM (B-phys) • Can this be connected to kinematic fitting in the analysis world..? The jury is out (3 possibilities) • Complex issues in the e/ EDM (due to material) • Need to go back/forth between ID and calo to best identify conv. (cut on elec ET not pT due to brem) • Need N:N ID:calo matches to cover all e/ cases in the EDM - tracks, clusters, error matrices, kin fits • Did not conclude on this - will be a long process! Charged/neutral tracks in tracking EDM, adding mass Zee faking H4e Zoo of e/ objects Richard Hawkings

18. Getting ready for data - monitoring • Subdetectors and ID global well advanced • Online & offline monitoring tested in cosmics • Offline monitoring tested in FDR exercises • Collisions look very different from cosmics - FDR first opportunity to do physics monitoring • Some concerns / things to be improved … • CPU and memory usage, code stability • Archiving to COOL, DQMF tools • Number and relevance of histograms • Tuning, warning thresholds need real data • Alignment monitoring is also well advanced • Tested in FDR1, spotted some problems • ‘Alignment’ monitoring has expanded to include comb-perf and physics monitoring • Discussions on restructuring at Ringberg • Difference between short/long-term plots (what can only be checked with lots of data) TRT online monitoring (M6) TRT calib problem in FDR1 Richard Hawkings

19. Getting ready for data - pre-collisions • Already started to work with cosmics in pit, need statistics and pixels! • Reconstruction works well, very useful for debugging, alignment/calibration • Record as many as possible before/during LHC commissioning • Beam-gas events (single beam running) • Rates and triggering are very uncertain • Few Hz at most ?? Will detectors be on? • Tracks distributed along z - potentially useful • Beam-halo events (1 & 2 beam running?) • Again, rates and triggering are uncertain • Horizontal cosmics - clearly useful if can be triggered by MB scintillators • In both cases, very hard to quantify in advance or justify a request - ‘wait and see’ approach? • Interactions with displaced IP (37 cm) • Again, potentially useful, a more concrete scenario for simulation if effort available • Will this be done at start up - come back later? Old study of beam-gas (Athens, 2003) RH / M Boonekamp Recon with iPatRec Rate ~25 Hz Richard Hawkings

20. When collisions come … • Or .. ‘I have nothing to offer you but blood, sweat, toil and tears’ … • Do everything we can now to be prepared - make sure all s/w tools are in place • Detector operation, finding tracks, calibration, alignment, material, physics … • Is your black hole shelter ready? This is not an OTSMU task Richard Hawkings

21. Towards understanding the first data … • Begin by looking at basic distributions • Low mass dimuons (already studied in FDR1) • E/p distributions (studies starting) • Will have to disentangle many effects • Misalignment, material, B-field, simulation … • Already some hints of how hard this will be • Previous experiments have used ‘fudge factors’ • Scaling error matrices, smearing tracks • Starting to develop the tools for this - can have significant effects e.g. on b-tagging performance • But will need to start simply … Low mass  B-tagging Effect of error scaling Additional material >0 E/p - fraction in tails Richard Hawkings

22. Conclusion:A few concerns / challenges / opportunities • Where we are suffering and struggling … • Software process and release preparation / validation • Persistency - complex, manpower intensive, limiting • Alignment package restructuring falling behind • Fragmentation of effort in some areas - need to agree baseline and focus on it • Where more effort is needed • Global alignment issues (ID-MS, ID-calo) • Triggering on cosmics in LHC fills - vital for constraining weak modes for alignment • Communication with physics/performance groups - role of Tracking group • Some known unknowns • How well will the detector work - hardware, cooling, occupancies, backgrounds • How well will the accelerator work - uptime/fill length, luminosity development • Will have a big effect on our data processing and reprocessing capability • Data distribution to outside institutes - CAF will not do everything • Make sure everyone can contribute to understanding the first data Richard Hawkings