1. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 1 Outline LHC Experiments SM physics Higgs SUSY Exotics

2. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 2 LHC uses existing CERN complex LHC is being built in the existing tunnel previously used for LEP –Circumference = 27 km Radius = 4.3 km Use existing accelerators as injection system Since the radius of the ring is fixed, one has to use very high-field magnets to reach high energy: 7 TeV p + 7 TeV p –fill as large a fraction as possible of the circumference with magnets 2/3 of ring with dipole magnets quadropole magnets for focusing straight sections for acceleration, detectors beam injection and dump systems

3. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 3 CERN LHC tunnel Lake Ring of 27 km

4. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 4 Four major “experiments” ATLAS and CMS are “general-purpose” detectors optimised for exploring new physics in pp collisions LHCb is a specialized detector for B-physics studies ALICE is a specialized detector for heavy-ion physics Major experiments

5. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 5 Major experiments

6. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 6 Energy and intensity Need very high energy and very high intensity to maximize the sensitivity to new physics Energy needed to produce new massive particles Intensity needed because: some of the processes that one would like to study are very rare and because the fraction of partons with high momentum is small

7. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 7 Need very high-field “two-in-one” magnets 15-meter long super-conducting magnet coils cooled to 1.9 K with super-fluid Helium –Field > 8 Tesla Compared to 4  5 Tesla at Tevatron and HERA As LHC collides beams of protons (not proton-antiproton as at Tevatron), one needs double magnets

8. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 8 Luminosity Want highest luminosity possible: Rate   ×L Access to rare high momentum partons and to low cross-section processes Beam parameters at LHC –N  10 11 ;  xy  15  m in ATLAS and CMS; f = 11 kHz; k = 2808

9. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 9 From virtual reality to real reality

10. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 10 Some LHC parameters Centre-of-mass energy –  s = 14 TeV for proton-proton collisions c.f. 2 TeV at Tevatron collider Equivalent to ~100,000 TeV or 10 17 eV fixed-target beam energy –  s = 6 TeV per nucleon for Pb-Pb collisions Luminosity –L = 10 34 cm -2 s -1 for proton-proton collisions in ATLAS and CMS c.f. L = 10 32 cm -2 s -1 at Tevatron –L = 10 27 cm -2 s -1 for Pb-Pb collisions (in ALICE and also ATLAS+CMS) Note: enormous energy stored in proton beams –331 MJ/beam (enough to melt 500 kg of copper) Rely on safe ejection of beams into beam dumps at end of coast Most of the protons used up in beam-beam collisions in experimental areas

11. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 11 More LHC Parameters Protons grouped in bunches –Bunch spacing is 25 ns in time (i.e. 7.5 meters in distance) Bunch-crossing rate is 40 MHz Start-up with 75 ns bunch spacing Total proton-proton cross-section  ~ 100 mb –Interaction rate at nominal L = 10 34 cm -2 s -1 is R ~ 10 9 Hz On average ~ 23 interactions per bunch crossing –Pile-up complicates analysis of what happened in the interaction of interest –LHCb uses L = 2×10 32 cm -2 s -1 to maximize rate of single-interaction bunch crossings Different focussing of beams to ATLAS and CMS –Rate much lower for heavy-ion case R ~ 10 4 Hz for Pb-Pb (low luminosity) –Much less than bunch-crossing rate (BC period = 125 ns for Pb ions)

12. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 12

13. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 13 Cryodipole overview

14. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 14 Cryomagnets interconnect in the tunnel

15. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 15

16. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 16 Optimistic LHC startup scenario End of dipole installation February 2007 First collisions – July 2007 43+43 bunches, gradually increase up to L= 10 32 cm -2 s -1 Pilot run : 936+936 bunches of 75 ns, increase up to L= 10 33 cm -2 s -1 Switch to 25 ns with 2808+2808 bunches Collect in pilot 2007 run ~10-100 pb -1 - calibration 2-3 months shutdown ?? In 2008 run with 2808+2808 bunches of 25 ns Gradual increase of luminosity up to L= 2 x 10 33 cm -2 s -1 Collect in the first physics run of ~7 months in 2008 ~10 fb -1

17. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 17 Luminosity assumptions First two years of LHC physics data taking 2008-2009 Optimistic scenario: ATLAS and CMS get each 30 fb -1 Moderate scenario: ATLAS+CMS get together 30 fb -1 Pessimistic scenario: ATLAS+CMS get each 10 fb -1

18. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 18 Usual wisdom of 1980s: LHC accelerator is straight forward LHC experiments are challenging What is the status of detectors ?

19. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 19 ALICE

20. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 20 ALICE end of 2005

21. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 21 ALICE TPC

22. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 22 LHCb Detector to one side of the collision point Use large rate of high-momentum beauty hadrons in forward direction see lecture of N.Harnew this school

23. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 23 LHCb end of 2005

24. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 24 CMS

25. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 25 CMS November 2005

26. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 26 ATLAS

27. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 27 ATLAS November 2005

28. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 28 Caverne ATLAS

29. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 29 Inner Detector Pixels: silicon hybrid pixels SCT: silicon strips TRT: straw tubes traker with transition radiation function solenoidal magnet(2T)

30. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 30 Silicon Tracking Detectors Silicon tracking detectors are reverse-biased junctions –The passage of a charged particle produces electron- hole pairs that are collected on strips or pixels Since the detectors are thin, the charge collection time is small –Signal processing is used to achieve a time resolution better than 25 ns Very large numbers of detector channels possible thanks to micro-electronics technology –Of the order of 10 7 sensor elements sampled at 40 MHz bunch-crossing rate!

31. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 31 >80 millions of pixels Radiation hard >80 millions of pixels Radiation hard 1 pixel : 50x400 μm² 1 pixel : 50x400 μm² 1 module : 47232 pixels ~6  2 cm² 1 module : 47232 pixels ~6  2 cm²  vertex and Impact parameters of charged particule 1,40 m 24 cm 3 discs 3 barrels

32. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 32 Pixels ATLAS Pixels 50 µm x 400 µm R=5 cm, 9 cm and 12 cm Destaged pixel layer

33. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 33 Pixel barrel ladders with 13 modules

34. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 34 Pixel disks of C-side

35. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 35 Barrel and one end-cap ready. Introduction of layer B3 ATLAS Barrel Si Strips

36. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 36 Un bouchon du SCT SCT endcap

37. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 37 TRT barrel Barrel and one end-cap ready.

38. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 38 Straw Tubes Straw-tube detectors achieve short charge collection time because of the small maximum drift distance (radius of straw) –The detectors consist of an anode wire running along the centre of a conducting straw –Electrons drift towards the wire and are amplified in the strong field near the wire surface ATLAS uses straw tubes for the outer part of its tracker –Foil or foam is used to produce transition radiation X-rays from electrons Produce high energy hits in straws used in electron identification Full detector contains ~400k channels –Time of arrival of charge measured and used to reconstruct tracks

39. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 39 “Exposure time” of one BC (25 ns) Muons coloured in yellow

40. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 40 Additional material

41. Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 2006 41 Commissioning Detector Scenario Initial ATLAS in DC1 layout (2 barrel pixels, 2 pixel disks, no TRT C-wheels) default inefficiency from the start-up 3% pixels, 2% chips, 1% modules b-layer inefficiency 1% chips, 0.5% modules but systematic error big, 2/4 % inefficiencies to be considered Pixel-SCT alignment after 3 months σ Rφ =20 μm, σ z =60 μm Pixel-SCT alignment after 6 months σ Rφ =10 μm, σ z =30 μm Pixel-SCT alignment after 9 months σ Rφ = 5 μm, σ z =15 μm Direct simulations needed to prove the feasibility of this scenario