1. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 1 The ATLAS Experiment Roger Jones Lancaster University

2. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 2 LHC will collide beams of protons at an energy of 14 TeV Using the latest super-conducting technologies, it will operate at about – 270 0 C, just above absolute zero of temperature. With its 27 km circumference, the accelerator will be the largest superconducting installation in the world. Large Hadron Collider

3. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 3 Big Questions: The Origin of Mass l Particle physics theories naturally produce predictions that have massless particles nParticles with mass break some of the pleasing symmetries nBut they have to be there l Peter Higgs proposed a mechanism to preserve the extremely successful massless theories but introduce masses through interactions through a Universal field nActs like a ‘treacle’ that slows motion the same way in all directions nWould have a signature, at least one new particle (the Higgs Boson) with well predicted properties - except its own mass l Cannot be too massive, or the theory breaks down l Cannot be too light, or we would have clearly seen it nIf we do not see it at the LHC, we need to re-write the text books- but it will be quite rare

4. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 4 Big Questions: Matter and Antimatter l We live in a universe of matter nPhysics process almost all treat matter and antimatter equally nWhy the imbalance? l CP violation can break the symmetry - but we do not see enough Could be because of new rare physics processes l Related to processes that can turn matter into antimatter (and vice versa) - mixing

5. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 5 New Physics l Supersymmetry nWould solve many questions about the observations already made nIf it is there it means there are partners to all our known particles to be found l Exotics l Hidden extra dimensions nMight be revealed in many ways - even micro black hole production nDon’t worry, micro black holes evaporate almost instantly! l We will take data with heavy ions collisions l Plus lots more info on ‘old physics’……

6. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 6 ATLAS Collaboration (Status October 2007) 6 Continents 37 Countries 167 Institutions 2000 Scientific Authors total (1600 PhD physicists, 400 students) 1000 Technical and support staff Albany, Alberta, NIKHEF Amsterdam, Ankara, LAPP Annecy, Argonne NL, Arizona, UT Arlington, Athens, NTU Athens, Baku, IFAE Barcelona, Belgrade, Bergen, Berkeley LBL and UC, HU Berlin, Bern, Birmingham, UAN Bogotá, Bologna, Bonn, Boston, Brandeis, Bratislava/SAS Kosice, Brookhaven NL, U Buenos Aires, Bucharest, Cambridge, Carleton, Casablanca/Rabat, CERN, Chinese Cluster, Chicago, Chilean Cluster (PUC Santiago + UTFSM Valparaiso), Clermont-Ferrand, Columbia, NBI Copenhagen, Cosenza, AGH UST Cracow, IFJ PAN Cracow, DESY, Dortmund, TU Dresden, JINR Dubna, Duke, Frascati, Freiburg, Geneva, Genoa, Giessen, Glasgow, Göttingen, LPSC Grenoble, Technion Haifa, Hampton, Harvard, Heidelberg, Hiroshima, Hiroshima IT, Indiana, Innsbruck, Iowa SU, Irvine UC, Istanbul Bogazici, KEK, Kobe, Kyoto, Kyoto UE, Lancaster, UN La Plata, Lecce, Lisbon LIP, Liverpool, Ljubljana, QMW London, RHBNC London, UC London, Lund, UA Madrid, Mainz, Manchester, Mannheim, CPPM Marseille, Massachusetts, MIT, Melbourne, Michigan, Michigan SU, Milano, Minsk NAS, Minsk NCPHEP, Montreal, McGill Montreal, FIAN Moscow, ITEP Moscow, MEPhI Moscow, MSU Moscow, Munich LMU, MPI Munich, Nagasaki IAS, Nagoya, Naples, New Mexico, New York, Nijmegen, BINP Novosibirsk, Ohio SU, Okayama, Oklahoma, Oklahoma SU, Oregon, LAL Orsay, Osaka, Oslo, Oxford, Paris VI and VII, Pavia, Pennsylvania, Pisa, Pittsburgh, CAS Prague, CU Prague, TU Prague, IHEP Protvino, Regina, Ritsumeikan, UFRJ Rio de Janeiro, Rome I, Rome II, Rome III, Rutherford Appleton Laboratory, DAPNIA Saclay, Santa Cruz UC, Sheffield, Shinshu, Siegen, Simon Fraser Burnaby, SLAC, Southern Methodist Dallas, NPI Petersburg, Stockholm, KTH Stockholm, Stony Brook, Sydney, AS Taipei, Tbilisi, Tel Aviv, Thessaloniki, Tokyo ICEPP, Tokyo MU, Toronto, TRIUMF, Tsukuba, Tufts, Udine/ICTP, Uppsala, Urbana UI, Valencia, UBC Vancouver, Victoria, Washington, Weizmann Rehovot, FH Wiener Neustadt, Wisconsin, Wuppertal, Yale, Yerevan

7. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 7 Diameter25 m Barrel toroid length26 m Endcap end-wall chamber span46 m Overall weight 7000 Tons Main detector systems

8. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 8 Collaboration organization

9. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 9 ATLAS Construction Construction and assembly at the surface came to an end Installation in the cavern is also nearing completion The cosmics Milestones Weeks have given a taste of the excitement we will enjoy in a few months (weeks!) from now…

10. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 10 CERN, 11-Feb-200810 A few images from recent activities in detector construction

11. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 11 CERN, 11-Feb-200811 The very last pieces of the ATLAS detector will be installed in the coming weeks Friday 8 February the first of the two ‘Small Wheels’ was transported from Hall 191 to Point-1

12. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 12 CERN, 11-Feb-200812 Here the ‘Small Wheel’ just before entering the Point-1 surface building SX1

13. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 13 CERN, 11-Feb-200813 It becomes more and more impossible to see the ATLAS detector as a whole in the cavern, here it is open to receive the SWs soon However there are still large activities inside in the barrel region, not visible to the visitors, to get ready for closure soon

14. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 14 CERN, 11-Feb-200814 One activity is on the Inner Detector, where finally the SCT ‘sign off’ could proceed, and leave the floor to the Pixels for final cabling and testing, under great schedule pressure This is of course an old picture, from last July, when the Pixels were installed…

15. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 15 CERN, 11-Feb-200815 The other major activities are on the calorimetry with the systematic refurbishing of the LAr FEBs and of the Tile drawers, all on track for completion end of March There is also very good progress in the repair of the damaged LAr cryoline for EC-C from last year’s ECT test incident (Again, this picture is an old one…)

16. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 16 Schedule by LHC sectors (end Jan 08)

17. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 17 ATLAS completion schedule

18. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 18 Cosmic rays in ATLAS from integration week M4 (Aug’07)  M5 was run in Oct-Nov’07  M6 was last week  Continuous data-taking from May’08 onwards

19. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 19 ATLAS Data Collection l Protons flying in opposite directions will collide with a centre-of-mass energy of 14 TeV (~14000 times the proton rest mass) in the centre of the ATLAS detector l Each such collision produces several hundreds of particles that are absorbed and detected by the ATLAS detector The ensemble of the electronic signals produced in all detector components by a single collision is called an “ event ” Events can take place at rates up to 40 MHz, but “ interesting ” ones will occur much more rarely (100-1000 Hz) The online data acquisition system will collect together all signals that belong to the same event and select “ interesting ” ones (max. rate 200 Hz, limited by bandwidth and offline processing) l These events are sent to the CERN computing centre (Tier-0) for processing and distribution

20. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 20 Event data flow from online to offline l Events are written in “ByteStream” format by the Event Filter farm in <=2 GB files n200 Hz trigger rate (independent of luminosity) nEvents will be grouped by “luminosity block” (1-2 minute intervals)  One luminosity block can be approximated as having constant luminosity  There should be enough information for each lumi block to be able to calculate the luminosity nNominal RAW event size is 1.6 MB/event nCurrently several streams are foreseen:  ~5 physics event streams, separated by main trigger signature le.g. muons, electromagnetic, hadronic jets, taus, minimum bias  Express stream with “most interesting” events to be processed immediately lInitially useful only for monitoring and calibration activities  Calibration events  “Trouble maker” events (for debugging) nEach file will contain events belonging to the same trigger stream, luminosity block and SFO (Event Filter Sub-Farm Output unit)  ~25 files/minute will be produced by the online system nData will be transferred to the Tier-0 input buffer at 320 MB/s (average)

21. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 21 Online DQA Online DQA RODs Front-end LVL1 LVL2 Event Builder SFI (s) EF SFOs T1 Oracle replica T2 replica RAW: 200Hz, 320MB/s express calib ESD 100MB/s AOD 20MB/s Online DB + Shift Log + DQ status + Archives Tier 0 T1 transfer MC valid. AMI Verify TAG DB + Calib/align + DQ status + Archives to Tier0 updated calib Offline DQA Offline DQA updated status initial status updates T1 (Late Reproc.) Prompt reco (bulk) Xpress reco, calibration T2 (MC prod.) DB from online Config, Calib DCS, DQ status PVSS-To-COOL (~15 min latency ?) DCS Data flow from DAQ to offline

22. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 22 Event Data Model l RAW: n“ByteStream” format, ~1.6 MB/event l ESD (Event Summary Data): nFull output of reconstruction in object (POOL/ROOT) format:  Tracks (and their hits), Calo Clusters, Calo Cells, combined reconstruction objects etc. nNominal size 1 MB/event initially, to decrease as the understanding of the detector improves  Compromise between “being able to do everything on the ESD” and “not enough disk space to store too large events” l AOD (Analysis Object Data): nSummary of event reconstruction with “physics” (POOL/ROOT) objects:  electrons, muons, jets, etc. nNominal size 100 kB/event (now 170 kB/event) l DPD (Derived Physics Data): nSkimmed/slimmed/thinned events + other useful “user” data derived from AODs and conditions data nNominally 10 kB/event on average  Large variations depending on physics channels l TAG: nDatabase (or ROOT files) used to quickly select events in AOD and/or ESD files

23. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 23 Necessity of Distributed Computing l We are going to collect raw data at 320 MB/s for 50k seconds/day and ~100 days/year nRAW data: 1.6 PB/year l Processing (and re-processing) these events will require ~10k CPUs full time the first year of data-taking, and a lot more in the future as data accumulate l Reconstructed events will also be large, as people want to study detector performance as well as do physics analysis using the output data nESD data: 1.0 PB/year, AOD data: >0.1 PB/year l At least 10k CPUs are also needed for continuous simulation production of at least 20-30% of the real data rate and for analysis l There is no way to concentrate all needed computing power and storage capacity at CERN nThe LEP model will not scale to this level l The idea of distributed computing, and later of the computing grid, became fashionable at the turn of the century and looked promising when applied to HEP experiments’ computing needs

24. Roger Jones: The ATLAS Experiment Ankara, Turkey - 2 May 2008 24 ATLAS Software & Computing Project l The ATLAS Collaboration has developed a set of software and middleware tools that enable access to data for physics analysis purposes to all members of the collaboration, independently of their geographical location. l Main building blocks of this infrastructure are: nThe Athena software framework, with its associated modular structure of the event data model, including the software for:  Event simulation;  Event trigger;  Event reconstruction;  Physics analysis tools. nThe Distributed Computing tools built on top of Grid middleware:  The Distributed Data Management system;  The Distributed Production System;  The Ganga/pAthena frameworks for distributed analysis on the Grid. l The presentations, discussions and tutorial sessions this week cover those aspects of the S&C developments that are most useful for physicists who wish to analyse ATLAS data.