1. F.Gianotti, ATLAS RRB, 20-4-2010 1 Collaboration and Management matters First results from 900 GeV and 7 TeV collision data (in particular: first observation of W  e ν, μν candidates at LHC) Physics prospects for 2010-2011 (a few examples …) Detector status, consolidation and upgrade: see M.Nessi’s talk ATLAS Status Report (Part II) Fabiola Gianotti, RRB, 20/4/2010 CERN-RRB-2010-009

2. F.Gianotti, ATLAS RRB, 20-4-2010 2 Collaboration and Management matters

3. F.Gianotti, ATLAS RRB, 20-4-2010 3

4. 4 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 Bogota, Bologna, Bonn, Boston, Brandeis, Brasil Cluster, Bratislava/SAS Kosice, Brookhaven NL, Buenos Aires, Bucharest, Cambridge, Carleton, CERN, Chinese Cluster, Chicago, Chile, Clermont-Ferrand, Columbia, NBI Copenhagen, Cosenza, AGH UST Cracow, IFJ PAN Cracow, SMU Dallas, UT Dallas, DESY, Dortmund, TU Dresden, JINR Dubna, Duke, Edinburgh, Frascati, Freiburg, Geneva, Genoa, Giessen, Glasgow, Göttingen, LPSC Grenoble, Technion Haifa, Hampton, Harvard, Heidelberg, Hiroshima IT, Indiana, Innsbruck, Iowa SU, Iowa, UC Irvine, 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, CPPM Marseille, Massachusetts, MIT, Melbourne, Michigan, Michigan SU, Milano, Minsk NAS, Minsk NCPHEP, Montreal, McGill Montreal, RUPHE Morocco, FIAN Moscow, ITEP Moscow, MEPhI Moscow, MSU Moscow, Munich LMU, MPI Munich, Nagasaki IAS, Nagoya, Naples, New Mexico, New York, Nijmegen, Northern Illinois University, BINP Novosibirsk, Ohio SU, Okayama, Oklahoma, Oklahoma SU, Olomouc, Oregon, LAL Orsay, Osaka, Oslo, Oxford, Paris VI and VII, Pavia, Pennsylvania, Pisa, Pittsburgh, CAS Prague, CU Prague, TU Prague, IHEP Protvino, Regina, Rome I, Rome II, Rome III, Rutherford Appleton Laboratory, DAPNIA Saclay, Santa Cruz UC, Sheffield, Shinshu, Siegen, Simon Fraser Burnaby, SLAC, NPI Petersburg, Stockholm, KTH Stockholm, Stony Brook, Sydney, Sussex, AS Taipei, Tbilisi, Tel Aviv, Thessaloniki, Tokyo ICEPP, Tokyo MU, Tokyo Tech, Toronto, TRIUMF, Tsukuba, Tufts, Udine/ICTP, Uppsala, UI Urbana, Valencia, UBC Vancouver, Victoria, Waseda, Washington, Weizmann Rehovot, FH Wiener Neustadt, Wisconsin, Wuppertal, Würzburg, Yale, Yerevan ~ 2988 Active physicists: -- ~ 1900 with a PhD, for M&O share -- ~ 1100 students 173 Institutions 37 Countries

5. F.Gianotti, ATLAS RRB, 20-4-2010 5 ATLAS active physicists age distribution All2690(< 35 y 47.2%) Male81.8%(< 35 y 44.0%) Female18.2%(< 35 y 61.3%) (Status 1.1.2010)

6. F.Gianotti, ATLAS RRB, 20-4-2010 6 Collaboration composition since the last RRB At the Collaboration Board (CB) meeting on 26 February 2010, the Collaboration unanimously admitted one new Institution: Northern Illinois University, USA (Tile calorimeter, Data Quality, Core software, Computing, Simulations for Upgrade) An Expression of Interest had been presented at the October 2009 CB. Members of the above Institution have been active in ATLAS for several years through affiliation to another Institution, contributing successfully to high-priority tasks for the experiment. The RRB is kindly requested to endorse the admission of this new Institution in the ATLAS Collaboration. The total number of Institutions (with voting rights in the CB) increases from 172 to 173 Furthermore, at the February CB meeting an Expression of Interest to join ATLAS has been submitted by a joint team (a “cluster” : 1 vote in the CB) from South-Africa: University of Johannesburg and University of Witwatersrand. Members of these teams are already active through affiliation to other Institutions Admission will be considered at the CB on 2 July 2010 If positive, ATLAS will have a new country and a new FA (DST)

7. F.Gianotti, ATLAS RRB, 20-4-2010 7 New since October RRB

8. F.Gianotti, ATLAS RRB, 20-4-2010 8 Operation Task sharing ATLAS operation [detector, data quality and calibration, software, world-wide computing, including all kinds of shifts...] requires ~ 800 FTE (physics is not an OT)  OT are distributed in a fair way across Institutions: proportional to the number of authors -- students get favorable treatment as they are weighted 0.75 -- new Institutions contribute more the first two years (weight factors 1.5, 1.25)  200 FTE (out of 800 total) are for shifts: ~ 50000 shifts in 2010 (~20 per author) -- 70% CERN-based (Control Room or on-call); 30% remote shifts -- we have recently reduced the number of Control Room shifts by 15% -- as we gain experience  less shifts in general, in particular less CERN-based shifts Funding Agency Covered-expected expected Distribution per FA in 2009 (CERN-based shifts not included) Zero means ok, negative is bad FTE requirements and FA contributions reviewed and updated yearly

9. F.Gianotti, ATLAS RRB, 20-4-2010 9 First LHC data-taking and first performance and physics results at √s= 900 GeV and 7 TeV

10. F.Gianotti, ATLAS RRB, 20-4-2010 10 Since the last RRB meeting (12 October 2009) Chronology of a fantastic escalation of events: 20 November: first beams circulating in the LHC 23 November: first collisions at √s = 900 GeV 8, 14, 16 December: few hours of collisions at √s = 2.36 TeV (the world record !) 16 December: end of first run 16 December- 28 February: Winter technical stop 27 February : machine operation started again 19 March : first (single) beams ramped up to 3.5 TeV 30 March : first collisions at 3.5+3.5 TeV 1 st April : first W candidate

11. F.Gianotti, ATLAS RRB, 20-4-2010 11 Data recorded by ATLAS √s=900 GeV √s=2.36 TeV √s=7 TeV Total number of events ~ 920k ~34k With stable beams (*) ~ 540k --- ~ 22M Int. luminosity stable beams (~30% uncertainty) ~ 12 μ b -1 --- ~ 400 μ b -1 Max peak L in ATLAS: ~ 7 x 10 26 cm -2 s -1 (*) Full detector (including tracker) on ATLAS data-taking efficiency at 7 TeV: > 95 % during stable beams Fraction of non-operational detector: percent level  see M.Nessi’s talk 2009 run 2010 run Max peak L in ATLAS : ~ 2 x 10 27 cm -2 s -1 1x1 colliding bunches (~ 10 10 p/bunch)

12. F.Gianotti, ATLAS RRB, 20-4-2010 12 Worldwide data distribution Typically 4h between Data Acquisition at the pit and data arrival at Tier2 (including reconstruction at Tier0) MB/s per day Total data throughput through the Grid: 1 st January to 15 th April 2010 MC reprocessing 2009 data reprocessing Start of 7 TeV data-taking JanFebMarchApril

13. F.Gianotti, ATLAS RRB, 20-4-2010 13 Most of available Tier-1/Tier-2 resources used in 2009 (e.g. ~ 97% of Tier-1 CPU) Continuous efforts to reduce resources requests without affecting physics and worldwide analysis capabilities, for instance: -- simulation CPU/event reduced by 25% at zero cost for physics -- amount of legacy data (e.g. cosmics) reduced significantly March 18 to April 18 Average number of concurrent analysis jobs vs time Start of 7 TeV data-taking 30 March-18 April: 1.3 million successful jobs 11.5 billion events processed 584 users Increasing usage of the Grid for analysis activities

14. F.Gianotti, ATLAS RRB, 20-4-2010 14 Support for ATLAS activities at Tier-1s and Tier-2s Personnel supporting ATLAS activities at Tier-1s and Tier-2s is given in the Table below (in FTE). These are not ATLAS members. We are grateful to FA for their support to such a crucial component in the working of a worldwide Collaboration

15. F.Gianotti, ATLAS RRB, 20-4-2010 15

16. F.Gianotti, ATLAS RRB, 20-4-2010 16

17. F.Gianotti, ATLAS RRB, 20-4-2010 17 First resonances popped up after a few days of collisions in November 2009 K0s  π+π-K0s  π+π- Λ  pπ - π 0  γ γ η  γ γ

18. F.Gianotti, ATLAS RRB, 20-4-2010 18 First resonances popped up after a few days of collisions in November 2009 K0s  π+π-K0s  π+π- Λ  pπ - π 0  γ γ η  γ γ These and other early observations and measurements indicated immediately that the detector was in excellent shape

19. F.Gianotti, ATLAS RRB, 20-4-2010 19 Pixels First data also showed remarkable agreement with the Geant4-based simulation in the (most difficult) soft regime. Two examples shown here. Years of efforts to model the detector details (material, imperfections, …) and validate the simulation against test-beam measurements paid off Sensitive to calorimeter performance (noise, coherent noise, dead cells, mis-calibrations, cracks, etc.), and cosmics and beam-related backgrounds Measured over full calorimeter coverage (360 0 in φ, |η| < 5, ~ 200k cells) Missing transverse energy resolution ν or new particle (weakly-interacting)  missing E T

20. F.Gianotti, ATLAS RRB, 20-4-2010 20 γ  e + e - conversions e+e+ e-e- γ conversion point R ~ 30 cm (1 st Silicon strip layer) p T (e + ) = 1.75 GeV, 11 TRT high-threshold hits p T (e - ) = 0.79 GeV, 3 TRT high-threshold hits 2009 data -- main source of electrons in the 900 GeV data

21. F.Gianotti, ATLAS RRB, 20-4-2010 21 γ  e + e - conversions e+e+ e-e- γ conversion point R ~ 30 cm (1 st Silicon strip layer) p T (e + ) = 1.75 GeV, 11 TRT high-threshold hits p T (e - ) = 0.79 GeV, 3 TRT high-threshold hits Beam pipe Pixel 1 Pixel 2 Pixel 3 SCT 1 -- main source of electrons in the 900 GeV data -- useful to map the inner detector material

22. F.Gianotti, ATLAS RRB, 20-4-2010 First 7 TeV collisions disclose immediately a different regime … 7 TeV beam spot (30 March 2010) 900 GeV beam spot (12 December 2009) Note: equal scales σ x ~ 45 μm σ y ~ 70 μm σ x ~ 200 μm σ y ~ 279 μm Beam spot size and location from prompt offline vertex reconstruction (available a few hours after first collisions)

23. F.Gianotti, ATLAS RRB, 20-4-2010 23 Hard di-jet event : un-calibrated jet transverse energies: ~ 300 GeV

24. F.Gianotti, ATLAS RRB, 20-4-2010 A pileup event in ATLAS (prob. per triggered event 1.8 x 10  4  expect ~910 pileup events in run) Pile-up event : two pp interactions inside the same bunch-crossing Probability of double interactions: ~ 10 -3

25. F.Gianotti, ATLAS RRB, 20-4-2010 25 First ATLAS physics paper: “Charged-particle multiplicities in pp interactions at √s = 900 GeV measured with the ATLAS detector at the LHC”, published in Phys.Lett.B Recently: measurement updated to include the first fill taken at 7 TeV on 30 March Inclusive, minimally model-dependent measurement: made over a well-defined kinematic region: ≥ 1 charged particle p T > 500 MeV, | η | <2.5 no subtraction for single/double diffractive components distributions corrected back to hadron level  easy to compare with MC models 7 TeV results are under approval The very precise ATLAS measurements provide strong constraints on available models

26. F.Gianotti, ATLAS RRB, 20-4-2010 26 First observation of W  e ν, μν candidates at the LHC W is the first milestone in the “rediscovery” of the Standard Model Other “candles”: J/ ψ (see later), Z (requires ~ 10 more data), top (requires ~ 10 pb -1 ) μ ν W Missing E T 300 μ b -1 of analysed data W  e ν W  μν Expected signal ~ 1.5 ~ 1.5 Observed candidates 2 2 Sign of candidates +, + +, - Note: -- pp collisions: σ (W + ) > σ (W - ) -- expected background : ~ 0.15 events -- leptons pass tight e/ μ cuts p T ( μ,ν ) ~ 40 GeV (~ m W /2) 1 st observed candidate: 1 st April

27. F.Gianotti, ATLAS RRB, 20-4-2010 27 2 nd observed candidate: 5 April Electron: 3 Pixel hits, 9 SCT hits, 37 TRT hits (20% with transition radiation), E/p~1.3

28. F.Gianotti, ATLAS RRB, 20-4-2010 28 3 rd observed candidate: 10 April Electron: 3 Pixel hits, 8 SCT hits, 34 TRT hits (35% with transition radiation), E/p~1

29. F.Gianotti, ATLAS RRB, 20-4-2010 29 4 th observed candidate: 12 April Muon: 3 Pixel hits, 8 SCT hits, 17 TRT hits, 14 MDT hits, Z~3mm from vertex, good tracker-spectrometer momentum match, E(calo) ~ 4 GeV (as expected)

30. F.Gianotti, ATLAS RRB, 20-4-2010 30 More than 200 plots approved A physics paper published in Phys. Lett. B 19 approved and 11 soon-to-be-approved CONF-notes for Winter/Spring conferences A “Detector performance paper” on 2009 data undergoing internal review ~ 40 CONF-notes and papers planned for Summer conferences Results produced so far: Detector works very well: -- ~ 1% of non-operational channels; data-taking efficiency larger than 95% -- performance is better than expected at this early stage (close to nominal) Very good agreement data-simulation in the (most difficult) soft regime tested so far (years of test-beam activities, material scrutiny, tune of G4 physics lists paid off..) Ability of the Collaboration to extract results very quickly (few hours after data-taking in some cases)  the whole experiment from detector operation at the pit to laptop analysis works efficiently  Excellent basis to produce more and more good physics results soon 3 main messages from the first periods of data-taking:

31. F.Gianotti, ATLAS RRB, 20-4-2010 31 What’s next ? Prospects for the 2010-2011 run Machine plan: 2010: L = ~10 27  10 32 cm -2 s -1  total of 100-200 pb -1 2011: L = 1  few 10 32 cm -2 s -1  ≥ 100 pb -1 per month  total of ~ 1 fb -1 2012: shut-down √s = 7 TeV Note: A few examples for illustration only … Very preliminary estimates using fast simulations in most cases, as studies of the ATLAS potential at √s = 7 TeV have just started

32. F.Gianotti, ATLAS RRB, 20-4-2010 32 Expected number of events in ATLAS for 100 pb -1 after cuts for some representative processes J/ ψ  μμ W  μν Z  μμ tt  μν+X inside peak (strong cuts) Note: with 1 fb -1 (end 2011): expected number of tt  l+jets events in ATLAS is ~ 2 times larger than CDF or D0 with 10 fb -1  expected “analyzable” luminosity at Tevatron by end 2011

33. F.Gianotti, ATLAS RRB, 20-4-2010 33 New Physics : approximate LHC reach √s = 7 TeV (one experiment) for some benchmark scenarios Z’ (SSM): Tevatron limit ~ 1 TeV (95% C.L) 50 pb -1 : exclusion up to ~ 1 TeV (95% C.L.) 500 pb -1 : discovery up to ~ 1.3 TeV exclusion up to ~ 1.5 TeV 1 fb -1 : discovery up to ~ 1.5 TeV W’ : Tevatron limit ~ 1 TeV (95% C.L) 10 pb -1 : exclusion up to 1 TeV 100 pb -1 : discovery up to ~ 1.3 TeV 1 fb -1 : discovery up to ~ 1.9 TeV exclusion up to ~ 2.2 TeV SUSY ( ) : Tevatron limit ~ 400 GeV (95% C.L) 100 pb -1 : discovery up to ~ 400 GeV 1 fb -1 : discovery up to ~ 700 GeV LHC will start to compete with the Tevatron in 2010, and should take over in 2011 in most cases.

34. F.Gianotti, ATLAS RRB, 20-4-2010 Higgs √s=7 TeV : H  WW, m H ~ 160 GeV (Tevatron exclusion: 162-166 GeV) 300 pb -1 per experiment : ~ 3 σ sensitivity combining ATLAS and CMS (similar to Tevatron) 1 fb -1 per experiment : could exclude 145 < m H < 180 GeV ~ 4.5 σ combining ATLAS and CMS Exclusion of the full mass range down to m H ~115 GeV requires ~1.5 fb -1 per experiment at 14 TeV Discovery for m H ~ 115 GeV requires ~ 10 fb -1 per experiment at 14 TeV A long way to go if the Higgs is just above the LEP2 limit: 2014 ? 34 Very preliminary estimates

35. F.Gianotti, ATLAS RRB, 20-4-2010 35 Conclusions ■ ATLAS has successfully collected first LHC pp data at √s = 900 GeV and √s =7 TeV We are grateful to the LHC team for the excellent performance of the machine ! ■ The whole experiment has worked efficiently and fast, from data taking at the pit, to data processing and transfer worldwide, to fast delivery of results. We are making efforts (as we gain experience) to reduce the number of shifts and CERN-based tasks. ■ The first data demonstrate that the performance of the detector and software tools (simulation, reconstruction, understanding of material, control of instrumental effects, …) is better than expected at this (initial) stage of the experiment, in a (soft) energy regime ATLAS was not optimized for. ■ Years of test beam activities, increasingly realistic simulations, and commissioning with cosmics were fundamental to achieve these nice results so quickly. ■ A first physics paper has been published, many more physics results are expected soon. This is only the beginning of an exciting physics phase, but already a major achievement of the worldwide ATLAS Collaboration. ■ Looking further ahead: activities to consolidate and upgrade the detector continue with vigor, in order to mitigate ageing, cope with increasing luminosity, enhance the performance  maximize the physics potential throughout ATLAS lifetime

36. F.Gianotti, ATLAS RRB, 20-4-2010 36 Conclusions ■ ATLAS has successfully collected first LHC pp data at √s = 900 GeV and √s =7 TeV We are grateful to the LHC team for the excellent performance of the machine ! ■ The whole experiment has worked efficiently and fast, from data taking at the pit, to data processing and transfer worldwide, to fast delivery of results. We are making efforts (as we gain experience) to reduce the number of shifts and CERN-based tasks. ■ The first data demonstrate that the performance of the detector and software tools (simulation, reconstruction, understanding of material, control of instrumental effects, …) is better than expected at this (initial) stage of the experiment, in a (soft) energy regime ATLAS was not optimized for. ■ Years of test beam activities, increasingly realistic simulations, and commissioning with cosmics were fundamental to achieve these nice results so quickly. ■ A first physics paper has been published, many more physics results are expected soon. This is only the beginning of an exciting physics phase, but already a major achievement of the worldwide ATLAS Collaboration. ■ Looking further ahead: activities to consolidate and upgrade the detector continue with vigor, in order to mitigate ageing, cope with increasing luminosity, enhance the performance  maximize the physics potential throughout ATLAS lifetime ATLAS is very grateful to the Funding Agencies for their huge contributions to the experiment and continuous support during almost 20 years.