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

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

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

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

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

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

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

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

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

Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February 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 eV fixed-target beam energy –  s = 6 TeV per nucleon for Pb-Pb collisions Luminosity –L = cm -2 s -1 for proton-proton collisions in ATLAS and CMS c.f. L = cm -2 s -1 at Tevatron –L = 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

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

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

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

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

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

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

Expectations of the first 2 years of LHC operations A.Rozanov ITEP Winter School of Physics February Luminosity assumptions First two years of LHC physics data taking 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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