1. Tom Dietel University of Cape Town for the ALICE Collaboration Computing for ALICE at the LHC

2. Outline Physics at the Large Hadron Collider Higgs – ATLAS & CMS Quark-Gluon Plasma – ALICE (+ATLAS,CMS) Computing for ALICE Present: Processing LHC Run-1 (2010-13) Near Future: Run-2 (2015-17) Long-Term Development: Run-3 (after 2018)

3. Large Hadron Collider collides protons and lead ions at >99.99999% of the speed of light to research the most fundamental particles and their interactions CMS LHCb ATLAS ALICE

4. Search for the Higgs Boson CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 4 quantum field fills universe field gives mass to elementary particles: W/Z, quarks, leptons new particle → Higgs boson Predicted in 1964 Peter Higgs R. Brout, F. Englert G. S. Guralnik, C. R. Hagen, and T. W. B. Kibble

5. ATLAS Higgs Candidate CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 5

6. Discovery of the Higgs Boson at LHC CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 6 Spring 2010 start of data taking 4 July 2012 discovery of a new particle March 2013 it’s a Higgs! October 2013 Nobel prize Extremely Rare few 100 Higgs in a quadrillion (10 15 ) collisions

7. Mass of the Proton - the other 99% CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 7 Proton contains 3 quarks 2 up-quarks: m u ≈ 2.5 MeV 1 down-quark: m d ≈ 5 MeV Proton heavier than 3 quarks 2u+1d: mass ≈ 10 MeV m p = 931 MeV 100 time heavier Where does the mass come from? Quantum-Chromodynamics Confinement: no free quarks

8. Quark-Gluon Plasma Compression reduce distance between nucleons Heating thermally create pions fill space between nucleons hadrons overlap quarks roam freely (deconfinement) Quark-Gluon Plasma CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 8

9. Heavy-Ion Physics Can the quarks inside the protons and neutrons be freed? What happens to matter when it is heated to 100000 times the temperature at the centre of the Sun? Why do protons and neutrons weigh 100 times more than the quarks they are made of? → collisions of heavy nuclei (Pb) at high energies

10. 10

11. ALICE Event Display CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 11

12. CERN and South Africa CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 12 SA-CERN home to all CERN research in South Africa 5 universities + 1 national lab more than 60 scientists SA-CERN home to all CERN research in South Africa 5 universities + 1 national lab more than 60 scientists ALICE heavy-ion physics quark-gluon plasma UCT, iThemba ALICE heavy-ion physics quark-gluon plasma UCT, iThemba ATLAS particle physics Higgs physics SUSY, BSM UCT, UKZN, UJ, Wits ATLAS particle physics Higgs physics SUSY, BSM UCT, UKZN, UJ, Wits ISOLDE rare isotope facility nuclear and atomic physics UKZN, UWC, Wits, iThemba ISOLDE rare isotope facility nuclear and atomic physics UKZN, UWC, Wits, iThemba Theory particle, heavy-ion and nuclear physics UCT, UJ, Wits Theory particle, heavy-ion and nuclear physics UCT, UJ, Wits

13. ALICE Data Flow CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 13 Event 1 readout of detectors approx. 1 collision (but: pile-up, empty events) data block: 1 (pp) to 100 MB (Pb-Pb) independent → embarrassingly parallel processing Event 1 readout of detectors approx. 1 collision (but: pile-up, empty events) data block: 1 (pp) to 100 MB (Pb-Pb) independent → embarrassingly parallel processing Storage disk buffer: short term, random access working copy long term (“tape”): backup Storage disk buffer: short term, random access working copy long term (“tape”): backup Reconstruction merge signals from same particle determine particle properties (momentum, energy, species) Reconstruction merge signals from same particle determine particle properties (momentum, energy, species) Simulation event generators model of known physics compare experiment / theory particle transport model of detectors correct for detector effects Simulation event generators model of known physics compare experiment / theory particle transport model of detectors correct for detector effects User Analysis extraction of physics results based on reconstructed data 100’s of different analysis at User Analysis extraction of physics results based on reconstructed data 100’s of different analysis at

14. Reconstruction – Bubble Chambers CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 14

15. Raw Data production: 7 PB Tom Dietel 15 pp@0.9-7 TeV PbPb@2.76 TeV pp@2.76-7 TeV PbPb@2.76 TeV pp@8 TeV pPb@5.02 TeV CHPC National Meeting, 4-6 Dec 2013 Big Data!

16. ALICE Grid Computing CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 16 Tier-0 CERN ( + Budapest) reco, sim, analysis 1 copy of raw data Tier-1 reco, sim, analysis 1 shared copy of raw data Tier-2 sim, analysis no access to raw data

17. ALICE Computing Resources tape storage (Tier-0: 22.8 PB, Tier-1: 13.1 PB) network human resources CPU Cores total: 44 000 cores Disk Storage (PB) total: 28.7 PB

18. ALICE GRID Sites Tom Dietel 18CHPC National Meeting, 4-6 Dec 2013

19. South African Tier-2 at CHPC CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 19 iQudu Cluster IBM e1350 cluster 160 nodes – 2 dual-core AMD Opteron @ 2.6 GHz – 16 GB RAM ethernet + infiniband 100 TB storage (xroot) launched in 2007 – high power consumption – aging hardware used by ALICE since October 2012

20. ALICE Computing at CHPC CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 20 Avg: 348 running jobs 1% of all ALICE jobs

21. Completed Jobs at CHPC CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 21 Start of grid @ CHPC Network Switch Failure 20000 jobs / month

22. Tom Dietel 22 CPU delivered 2012 South Africa 0.3% projection for 2013: ~ 1% Resources Sharing CHPC National Meeting, 4-6 Dec 2013

23. CPU Requirements – RUN2 Tom Dietel 23 +60% CHPC National Meeting, 4-6 Dec 2013

24. Disk Requirements – RUN2 Tom Dietel 24 ×2.3 CHPC National Meeting, 4-6 Dec 2013

25. CHPC Upgrade WLCG sign MoU in (April) 2014 representation in WLCG replace grid cluster (iQudu) first quarter of 2014 2000 cores @ 3.2 GHz 900 TB storage ALICE + ATLAS additional human resources goal: Tier-1 Parallel session “CHPC Roadmap” Fri morning

26. ALICE LS2 Upgrade CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 26 2018/19 (LHC 2nd Long Shutdown) 50 kHz Pb-Pb collisions ALICE Hardware Upgrade Inner Tracking System (ITS) Time Project Chamber Change of Strategy all data into online computing farm continuous readout of detectors massive online processing

27. ALICE Challenges for Run-3 data rates – reduce 1 TB/s to 30 GB/s – data compression – use partial reconstruction overlapping events – process time-slices – major change in data model DetectorEvent Size (MB) Bandwidth (GByte/s) TPC20.01000 TRD1.681.5 ITS0.840 Others0.525 Total22.91146.5

28. CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 28 Computing Working Groups CWG1 Architecture CWG2 Tools CWG1 Architecture CWG2 Tools CWG3 Dataflow CWG1 Architecture CWG2 Tools CWG3 Dataflow CWG4 Data Model CWG5 Computing Platforms CWG6 Calibration CWG1 Architecture CWG2 Tools CWG3 Dataflow CWG4 Data Model CWG5 Computing Platforms CWG6 Calibration CWG7 Reconstruction CWG1 Architecture CWG2 Tools CWG3 Dataflow CWG4 Data Model CWG5 Computing Platforms CWG6 Calibration CWG8 Physics Simulation CWG7 Reconstruction CWG1 Architecture CWG2 Tools CWG3 Dataflow CWG4 Data Model CWG5 Computing Platforms CWG1 Architecture CWG2 Tools CWG3 Dataflow CWG4 Data Model CWG5 Computing Platforms CWG6 Calibration CWG8 Physics Simulation CWG7 Reconstruction CWG9 QA, DQM CWG1 Architecture CWG2 Tools CWG3 Dataflow CWG4 Data Model CWG5 Computing Platforms CWG6 Calibration CWG9 QA, DQM CWG10 Control, Configuration CWG8 Physics Simulation CWG7 Reconstruction CWG1 Architecture CWG2 Tools CWG3 Dataflow CWG4 Data Model CWG5 Computing Platforms CWG6 Calibration CWG9 QA, DQM CWG10 Control, Configuration CWG11 Software Lifecycle CWG8 Physics Simulation CWG7 Reconstruction CWG1 Architecture CWG2 Tools CWG3 Dataflow CWG4 Data Model CWG5 Computing Platforms CWG6 Calibration CWG9 QA, DQM CWG12 Computing Hardware CWG10 Control, Configuration CWG11 Software Lifecycle CWG8 Physics Simulation CWG7 Reconstruction CWG1 Architecture CWG2 Tools CWG3 Dataflow CWG4 Data Model

29. Summary Present ALICE computing part of WLCG – more than 40000 CPU cores – almost 30 TB of data – Big Data! South Africa – CHPC – 1% of ALICE resources Near Future growth within current computing model upgrade of CHPC – towards Tier-1 Long-term Future major ALICE upgrade → extreme data rates new computing concepts → huge R&D effort

30. CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 30 Backup

31. AliRoot CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 31

32. O 2 Project Institution Boards Computing Board Online Institution Board Computing Working Groups Projects O 2 Steering Board Project Leaders DAQ CWG1 Architecture CWG2 Procedure & Tools HLT CWG3 DataFlow CWG4 Data Model Offline CWG5 Platforms CWG6 Calibration CWG13 Sw Framework CWGnn ----- CWG7 Reconstruc. CWG8 Simulation CWGnn ----- CWGnn ----- CWGnn ----- CWGnn ----- CWG9 QA, DQM, Vi CWG10 Control CWG11 Sw Lifecycle CWG12 Hardware - 50 people active in 1-3 CWGs - Service tasks

33. O 2 Hardware System 2 x 10 or 40 Gb/s FLP 10 Gb/s FLP ITS TRD Muon FTP L0 L1 FLP EMC FLP TPC FLP TOF FLP PHO Trigger Detectors ~ 2500 links in total ~ 250 FLPs First Level Processors EPN Data Storage EPN Storage Network Storage Network Farm Network Farm Network 10 Gb/s ~ 1250 EPNs Event Processing Nodes

34. CHPC National Meeting, 4-6 Dec 2013 Tom Dietel 34 Dataflow Model