1. Four Seas Conference Iasi, Romania, 30 May 2007 Overview of the CMS Experiment Claudia-Elisabeth Wulz CMS Collaboration Institute for High Energy Physics Austrian Academy of Sciences http://cms.cern.ch

2. Four Seas, May 2007C.-E. Wulz2 Questions CMS will help to answer How must the Standard Model be extended? Supersymmetry, Grand Unified Theories, … What is the origin of mass - electroweak symmetry breaking? Search for Higgs particle(s), measure their masses Can all forces be unified? How can gravity be incorporated? Are there extra dimensions? Do quarks and leptons have substructure? Are there more than 3 generations? Why is there matter-antimatter asymmetry? What is the dark matter of the cosmos? Quantumchromodynamic confinement Quark-Gluon-Plasma How did the universe begin?

3. Four Seas, May 2007C.-E. Wulz3 LHC SPS CMS TOTEM ATLAS ALICE Large Hadron Collider LHCf

4. Four Seas, May 2007C.-E. Wulz4 Exploded view of CMS MAGNET COIL VERY-FORWARD CALORIMETER HADRON CALORIMETER HB HE ELECTROMAGNETIC CALORIMETER HF SILICON STRIP TRACKER PIXEL DETECTOR PRESHOWER DETECTOR IRON YOKE BARREL MUON CHAMBERS (DT+RPC) ENDCAP MUON CHAMBERS (CSC+RPC)

5. Four Seas, May 2007C.-E. Wulz5 CDF Transverse slice through CMS

6. Four Seas, May 2007C.-E. Wulz6 Task: measure precisely charged particle momenta and trajectories, determine primary and secondary vertices -> all silicon tracker with pixel detector. At design luminosity of 10 34 cm -2 s -1 on average 1000 tracks from 20 superposed interactions. Inner Tracker Transverse momentum resolution Transverse impact parameter resolution 220 m 2 of Si sensors, 10.6 million Si strips, 65.9 million pixels

7. Four Seas, May 2007C.-E. Wulz7 Pixel Detector It surrounds the interaction point. Barrel layers are at radii 4, 7, and 11 cm. Forward layers are at ±34 and ±46 cm from interaction point. Its silicon pads provide high-resolution (10 to 20  m) patterns of space points. Secondary vertices, which may arise from particles containing Beauty- Quarks, are identified. Such particles are especially important in the search for the Higgs particle or for Supersymmetry. Pixel size 100  m x 150  m; 16000 readout chips (ROC) in 0.25  m CMOS technology, bump-bonded to the silicon sensors; Challenging radiation environment (100 Mrad in 10 years).

8. Four Seas, May 2007C.-E. Wulz8 radius: 4 cm radius: 7 cm radius: 11 cm Pixel Detector Mechanics Barrel structure The pixel detector will be installed before summer 2008. Endcap half-disk

9. Four Seas, May 2007C.-E. Wulz9 Silicon Strip Tracker TIB TEC layer TEC at Tracker Integration Facility

10. Four Seas, May 2007C.-E. Wulz10 Tracker Inner Barrel inserted in Outer Barrel

11. Four Seas, May 2007C.-E. Wulz11 Status of Silicon Strip Tracker Cosmic  All parts of the SST are inserted in its support tube. Tests with cosmic muons are underway at the Tracker Integration Facility. Installation in CMS should begin in mid July 2007.

12. Four Seas, May 2007C.-E. Wulz12 Electromagnetic Calorimeter A homogenous calorimeter of PbWO 4 crystals read out by photodetectors was chosen. Advantages: excellent energy resolution, fast, highly granular, radiation resistant. Barrel: 61200 crystals, read out with 2 Avalanche Photo Diodes each. Endcaps: 14648 crystals, read out with Vacuum Photo Triodes.

13. Four Seas, May 2007C.-E. Wulz13 ECAL performance Test beam measurement Benchmark channel H->  requires diphoton mass resolution of ~ 0.5%, good angular resolution and  0 -rejection. More on ECAL in Nicolo Cartiglia’s talk!

14. Four Seas, May 2007C.-E. Wulz14 ECAL layout and status 36 Supermodules Endcap Dee Barrel crystals Preshower detector All barrel crystals, manufactured largely in Russia with some in China, are delivered. Endcap crystal delivery from Russia and China is ongoing and foreseen to end in Feb. 2008. 18 out of 36 Supermodules are installed underground. The complete barrel is foreseen to be assembled in mid 2007. Endcaps will be installed during shutdown in first half of 2008.

15. Four Seas, May 2007C.-E. Wulz15 Electromagnetic Calorimeter Supermodules

16. Four Seas, May 2007C.-E. Wulz16 ECAL first half-barrel Installation finished on 22 May 2007!

17. Four Seas, May 2007C.-E. Wulz17 Preshower Detector Task: separate photons from  0 ’s and identify diphoton vertex. Two-layer sampling calorimeter consisting each of a lead absorber and silicon microstrip detectors (320  m thick sensors, 32 strips with pitch of 1.9 mm) behind. 2 X o 1 X o

18. Four Seas, May 2007C.-E. Wulz18 Hadronic Calorimeter Task: measure energies of hadron jets and determine missing energy. The central part (barrel + endcaps) consists of alternating plates of brass and plastic scintillator read out by photodiodes through wavelength shifting optical fibres. Barrel HCAL Endcap HCAL More on HCAL in Jordan Damgov’s talk!

19. Four Seas, May 2007C.-E. Wulz19 Installation of the barrel Hadronic Calorimeter

20. Four Seas, May 2007C.-E. Wulz20 HCAL + side in underground cavern

21. Four Seas, May 2007C.-E. Wulz21 Forward Hadronic Calorimeter Very forward HCAL In the forward regions calorimetry is completed by the Forward HCAL made of steel absorber plates sampled by quartz fibres due to their good radiation tolerance. They are read out by conventional photomultipliers, since the magnetic flux density is much lower than in the central region.

22. Four Seas, May 2007C.-E. Wulz22 Magnet Coil CMS has the world’s largest superconducting solenoid magnet. It provides a uniform magnetic flux density of 4 T at an operating temperature of 4.5 K, with a stored energy of 2.5 GJ, a nominal current of 19000 A. Conductor: Al-reinforced Nb-Ti strands in copper coating. Superconducting cable Pure Aluminum Al alloy Pipes for helium Electron-beam welds

23. Four Seas, May 2007C.-E. Wulz23 Coil Construction 5 modules Coil insertion Insertion of inner vacuum tank Sep. 2005 Aug. 2005

24. Four Seas, May 2007C.-E. Wulz24 Central wheel lowering (28 Feb. 2007)

25. Four Seas, May 2007C.-E. Wulz25 Installation of the central wheel

26. Four Seas, May 2007C.-E. Wulz26 Muon System For redundancy and robustness, 3 types of muon detectors, are used both for precision tracking and triggering: drift tubes (barrel), cathode strip chambers (endcaps), resistive plate chambers (barrel, endcaps). Requirements: Momentum resolution:  p T /p T ~ 8 to 15 % (10 GeV),  p T /p T ~ 20 to 40 % (1 TeV) (standalone)  p T /p T ~ 1 to 1.5 % (global) Position resolution: ~ 250  m (single chamber) ~ 100  m (chambers in combination) Timing resolution: better than 1 bunch crossing (25 ns) More on muon system in Leander Litov’s talk!

27. Four Seas, May 2007C.-E. Wulz27 Muon system layout DT CSC

28. Four Seas, May 2007C.-E. Wulz28 Drift tube chambers  -plane  -plane  -plane Anode Cathode Anode Cathode Drift tube cell Cosmic seen in DTs 

29. Four Seas, May 2007C.-E. Wulz29 Drift tube chambers in magnet yoke

30. Four Seas, May 2007C.-E. Wulz30 Cathode strip chambers

31. Four Seas, May 2007C.-E. Wulz31 CSC endcap disks Cathode strip chambers

32. Four Seas, May 2007C.-E. Wulz32 Resistive plate chambers Double-gap chambers, with 2 mm gas gap. Bakelite resistivity (2…5) x 10 10  cm. Timing resolution better than 2 ns -> use for triggering.

33. Four Seas, May 2007C.-E. Wulz33 Endcap disk with RPCs Resistive plate chambers

34. Four Seas, May 2007C.-E. Wulz34 Installation of the CMS Endcaps

35. Four Seas, May 2007C.-E. Wulz35 Trigger 3.2  s

36. Four Seas, May 2007C.-E. Wulz36 Level-1 Trigger Task: analyse each bunch crossing (calorimeters and muon systems only), every 25 ns, select for further processing by High-Level Trigger or reject. Decision based on logic combinations of trigger objects for which energy or momentum, but also location and quality information (if applicable) are available. Global Trigger crate

37. Four Seas, May 2007C.-E. Wulz37 Data Acquisition

38. Four Seas, May 2007C.-E. Wulz38 Computing, Software, Analysis CMS is now making full use of worldwide LHC Computing Grid. A combined Computing, Software and Analysis Challenge has been performed in 2006 (CSA2006). More than 200 million events reconstructed at Tier-0 centre at CERN. More than 1 Petabyte of data transferred on network across Tier-0, the 7 Tier-1s and selected Tier-2s. More than 50000 analysis jobs per day. Prompt reconstruction at 100 Hz was achieved using 1400 CPUs. From Sep. 2007 CSA2007 will aim to handle 50% of expected data in 2008. ~7

39. Four Seas, May 2007C.-E. Wulz39 Magnet Test and Cosmic Challenge Goal: operate selected parts of CMS including trigger, data acquisition, detector control systems and data quality monitoring together as a unified detector, with magnetic field. Performed successfully on the surface in summer 2006, with 30 million cosmic events recorded. Pipes for helium

40. Four Seas, May 2007C.-E. Wulz40 Event from MTCC Pipes for helium Next Magnet Test and Cosmic Challenge: autumn 2007 Aug. 2006

41. Four Seas, May 2007C.-E. Wulz41 Startup Plan for CMS / LHC Global runs (cosmics, test data): 1 week at end of each month, starting in May 2007 Computing, Software and Analysis Challenge: Sep. 2007 CMS ready to close: Oct. 2007 Engineering run with collisions at 900 GeV or cosmics: Nov. 2007, without ECAL endcaps and pixelsShutdown: Spring 2008 Close of experiment for 14 TeV collisions: April 2008 Start of 14 TeV physics run: June 2008, with ECAL endcaps and pixels Projected integrated luminosities: 1 fb -1 (2008), 5 fb -1 (2009)

42. Four Seas, May 2007C.-E. Wulz42 Conclusions CMS construction is coming to an end. Extensive tests of complete detector system will be performed throughout 2007. We look forward to the exciting physics to come! Thanks to my CMS colleagues and to you for your attention!

43. Four Seas, May 2007C.-E. Wulz43