Heavy Ions LHC l Heavy Ion Physics in

Heavy Ions @ LHC l Heavy Ion Physics ð (in VERY general terms) l Heavy Ion Physics at LHC l ALICE ð Collaboration ð Detector ð Performance Korea Oct 2004 HI@LHC J. Schukraft 1

Pretty Messy … 2 NA 35 streamer chamber picture, ca 1990 Korea 2004 J. Schukraft

The QCD Phase transition l QGP = true ground state of QCD ð I) melting matter => deconfinement ð II) melting vaccum (gluon condensate) =>chiral symmetry restoration µ dynamical origin of constituent mass l Phase transitions involving elementary quantum fields ð phase transitions and spontaneous symmetry breaking central to HEP ð QCD transition is the only one accessible dynamically l Cosmology & Astrophysics ð early Universe at ~ 1 ms ð interior of neutron stars l new domain of hot & dense QCD 3 ð surprises ?

Melting Matter (deconfinement) 4

The Dark Mystery of Mass What stuff is the Universe made of ? ? l Elementary Particles 0. 1% ð 12 matter particles (quarks, leptons) µ only 4 relevant today (u, d, e, n) ð 13 force particles (3 massive, 10 massless) l Composite Particles (hadrons) 4% l Dark Matter ð made of unknown particles l Dark Energy 73% ð vacuum energy µ of completely unknown origin ð should be infinite or exactly 0 ð hundreds… µ only 2 are relevant (p, n), making nuclei ð luminous normal matter (stars, galaxies) 0. 05% ð dark normal matter (gas, planets, . . ) 3. 95% 5 23% We don’t know how and why for ~ 5% We don’t even know what for the other 95%

Physics at LHC 6 Korea 2004 J. Schukraft

Current hunting ground for Quark Gluon Plasma The Relativistic Heavy Ion Collider 7

Future place for studying the Quark Gluon Plasma The Large Hadron Collider 8

LHC Status l long & winding road to LHC ð first discussion on HI in LHC: 1990 ð LHC approved 1994 /1996 ð start-up several times postponed l financial problems ð some 20% cost overrun (~800 MCHF) l technical problems ð Cryoline installation late > 1 year l machine well into construction ð > 1/3 of magnets produced l LHC start-up still expected in 2007 ð first heavy ion run in 2008 9 Korea 2004 J. Schukraft

LHC Magnets Main Dipole MQW Transfer Lines Insertion (Japan) 10 Korea 2004 J. Schukraft

Heavy Ions in LHC l energy ð ð Ebeam = 7 x Z/A Ös = 5. 5 Te. V/A (Pb-Pb), [Te. V] 14 Te. V (pp) l beams ð possible combinations: pp, p. A, AA µ constant magnetic rigidity/beam ('single magnet') ð expected heavy ion running µ ~ 6 weeks heavy ion runs, typically after pp running (like at SPS) µ initial emphasis on Pb-Pb µ pp and p. A comparison runs µ intermediate mass ion (eg Ar-Ar) to vary energy density ð later options: different ion species, lower energy AA and pp l luminosity 11 Korea 2004 J. Schukraft

H. I. Physics@LHC: Caveat BIG Step ahead: SPS x 12 RHIC x 28 LHC l long distance QCD is difficult to predict Predictions are notoriously difficult, in particular if they concern the future. . ð Theory well known, not so its consequences or manifestation ð HEP@LHC: Theory unknown, but each candidate makes precise predictions l the fate of 'expectations' at SPS and RHIC ð some expectations turned out right: µ SPS: strangeness enhancement ð some turned out wrong: µ SPS: large E-by-E fluctuations ð a number of unexpected surprises: µ SPS: J/Psi suppression RHIC: particle ratios, jet-quenching RHIC: multiplicity d. N/dy RHIC: elliptic flow, 'HBT-puzzle' l lesson when preparing ALICE at LHC ð guided by theory and expectations, but stay open minded ! l 'conventional wisdom' ð soft physics: smooth extrapolation of SPS/RHIC ð hard physics: new domain at LHC 12 necessary, but boring ? ? ? Korea 2004 J. Schukraft

Hard Processes at the LHC l Main novelty of the LHC: large hard cross section ~2% at SPS ~50% at RHIC ~98% at LHC X 2000 l Hard processes are extremely useful tools ð happen at t = 0 (initial stage of the collision) ð have large virtuality Q and small “formation time” Dt 1/Q ð probe matter at very early times (QGP) !!! hard processes can be calculated by p. QCD predicted 13 Korea 2004 J. Schukraft

Jets in ALICE | |<0. 9 l ideal energy for jet-quenching: around 100 Ge. V ð p. QCD applicable ð jets measurable above soft background ð energy loss still relatively large effect µ DE/E ~ O(10%), decreasing with E ! pp L = 1030 cm-2 s-1 Pb Pb rates: Reasonable rate up to ET ~300 Ge. V 14 pt jet > (Ge. V/c) jets/event accepted jets/month 5 3. 5 102 4. 9 1010 50 7. 7 10 -2 1. 5 107 100 3. 5 10 -3 8. 1 105 150 4. 8 10 -4 1. 2 105 200 1. 1 10 -4 2. 8 104 Korea 2004 J. Schukraft

Heavy Quarks & Quarkonia l copious heavy quark production ð charm @ LHC ~ strange @ SPS µ hard production => 'tracer' of QGP dynamics (statistical hardonization ? ) µ 2 mc ~ saturation scale => change in production ? µ jet-quenching with heavy quarks visible in inclusive spectra ? RHIC LHC l Y ds/dy LHC ~ 20 x RHIC ð Y will probably need higher Lumi at RHIC ð even at LHC Y'' is difficult Y production R. Vogt, hep-ph/0205330 15 Korea 2004 J. Schukraft

Initial Conditions l my pre-RHIC guess (QM 2001) ð still expect conditions to be significantly different ð only LHC will give the final answer on dn/dy! Central collisions Significant gain in e, V, t » x 10 SPS -> LHC » x 3 -5 RHIC -> LHC 16 SPS RHIC LHC s 1/2(Ge. V) 17 200 5500 d. Nch/dy 430 700 -1500 2 -8 x 103 e (Ge. V/fm 3)t 0=1 fm 2. 5 3. 5 -7. 5 15 -40 Vf(fm 3) 103 (? )7 x 103 2 x 104 t. QGP (fm/c) <1 1. 5 -4. 0 4 -10 t 0 (fm/c) ~1 ~0. 5 <0. 2 Korea 2004 J. Schukraft

The Soft Stuff l changes in expansion dynamics & freeze-out ARE expected ð thermal freeze-out temperature ? ð how will charm fit into particle ratios ? ð Event-by-Event fluctuations ? µ measurement accuracy ~ Ö#particles ð will elliptic flow continue to rise ? ð will the measured transverse HBT volume (finally) increase ? Freeze-out Hyper surface SPS LHC Biggest surprise would be none. . 17 Korea 2004 J. Schukraft

TOF HMPID TRD TPC PMD ITS Muon Arm PHOS 18 Size: 16 x 26 m Weight: ~10, 000 tons ALICE Set-up Korea 2004 J. Schukraft

ALICE Acceptance l central barrel -0. 9 < < 0. 9 ð tracking, PID ð single arm RICH (HMPID) ð single arm em. calo (PHOS) l forward muon arm 2. 4 < < 4 ð absorber, dipole magnet tracking & trigger chambers l multiplicity -5. 4 < < 3 ð including photon counting in PMD l trigger & timing dets ð Zero Degree Calorimeters ð T 0: ring of quartz window PMT's ð V 0: ring of scint. Paddles 19 Korea 2004 J. Schukraft

ALICE Collaboration ~ 1000 Members (63% from CERN MS) ~30 Countries ~80 Institutes 20 Korea 2004 J. Schukraft

ALICE Design Philosophy l General Purpose Heavy Ion Detector ð one single dedicated HI expt at LHC µ ATLAS/CMS will contribute, but priority is pp physics µ AGS/SPS: several (6 -8) 'special purpose expts' µ RHIC: 2 large multipurpose + 2 small special purpose expts l cover essentially all known observables of interest ð comprehensive study of hadrons at midrapidity µ large acceptance, excellent tracking and PID ð state-of-the-art measurement of direct photons µ excellent resolution & granularity EM calo (small but performing !) ð dedicated & complementary systems for di-electrons and di-muons ð cover the complete spectrum: from soft (10's of Me. V) to hard (100's of Ge. V) l stay open for changes & surprises ð high throughput DAQ system + powerful online intelligence ('PC farm‘, HLT) µ flexible & scalable: minimum design prejudice on what will be most interesting 21 Korea 2004 J. Schukraft

l still largest magnet ð magnet volume: 12 m long, 12 m high ð 0. 5 T solenoidal field The ALICE Magnet: ready for the experiment to move in! 22 Korea 2004 J. Schukraft

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ALICE R&D 1990 -1996: Strong, well organized, well funded R&D activity l Inner Tracking System (ITS) ð Silicon Pixels (RD 19) ð Silicon Drift (INFN/SDI) ü ð Silicon Strips (double sided) ü ð low mass, high density interconnects ð low mass support/cooling ü l TPC ð Pestov Spark counters V ð Parallel Plate Chambers V ð Multigap RPC's (LAA) ð low cost PM's V ð solid photocathode RICH (RD 26) l DAQ & Computing ð gas mixtures (RD 32) ü ð new r/o plane structures V ð advanced digital electronics ð low mass field cage ü l em calorimeter ð new scint. crystals (RD 18) 24 l PID ð scalable architectures with COTS ð high perf. storage media ? ð GRID computing ? ? l misc ð micro-channel plates V ð rad hard quartz fiber calo. ð VLSI electronics ü • R&D made effective use of long (frustrating) wait for LHC • was vital for all LHC experiments to meet LHC challenge ! ü Korea 2004 J. Schukraft

Time of Flight Detectors l aim: state-of-the-art TOF at ~1/10 current price ! ð requirements: area > 150 m 2, channels ~ 150, 000, resolution s < 100 ps ð existing solution: scintillator + PM, cost > 120 MSF ! µ R&D on cheaper fast PM's in Russia failed to deliver l gas TOF counters + VLSI FEE ð Pestov Spark Counter (PSC) 100 mm gap, > 5 k. V HV, 12 bar, sophisticated gas µ s < 50 ps, some 'tails' (? ), but only (!) ~ 1/5 cost µ technology & materials VERY challenging µ ð Parallel Plate Chamber (PPC) µ 1. 2 mm gap, 1 bar, simple gas & materials 1/10 cost, but only s = 250 ps µ unstable operation, small signal µ ð Multigap Resistive Plate Chambers (MRPC) µ breakthrough end 1998 after > 5 years of R&D ! many small gaps (10 x 250 mm), 1 bar, simple gas & materials µ ~ 1/10 cost, s < 100 ps , simple construction & operation, . . µ 25 Korea 2004 J. Schukraft

Inner Tracking System (ITS) SSD SDD SPD Lout=97. 6 cm Rout=43. 6 cm l 6 Layers, three technologies (keep occupancy ~constant ~2% for max mult) ð Silicon Pixels (0. 2 m 2, 9. 8 Mchannels) ð Silicon Drift (1. 3 m 2, 133 kchannels) ð Double-sided Strip (4. 9 m 2, 2. 6 Mchannels) 26 Material Budget: < 1% X 0 per layer ! Major technological challenge! Korea 2004 J. Schukraft

(all full-custom designs in rad. tol. , 0. 25 mm process) Analogue memory ADC ALICE SDD FEE Pascal chip: 64 channel preamp+ 256 -deep analogue memory+ ADC Ambra chip: 64 channel derandomizer chip s ALICE SSD FEE HAL 25 chip: 128 channels Preamp+s/h+ serial out Preamplifiers ALICE PIXEL CHIP 50 µm x 425 µm pixels 8192 cells Area: 12. 8 x 13. 6 mm 2 13 million transistors ~100 µW/channel ITS Electronics Developments And extreme lightweight interconnection techniques: SSD tab-bondable Al hybrids 27

Strip module assembly Pixel ladder Drift cooling system 28 System testing and series production

Tracking Challenge ALICE 'worst case' scenario: d. N/dych = 8000 NA 49 STAR 29 Korea 2004 J. Schukraft

TPC l largest ever ð 88 m 3, 570 k channels drift gas 90% Ne - 10%CO 2 Central Electrode Prototype 25 µm aluminized Mylar on Al frame Field Cage 30 diameter ~3 m Inner Vessel Korea 2004 J. Schukraft

TPC Field Cage 31

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TPC R/O chambers l production finished in Bratislava and GSI 33 Korea 2004 J. Schukraft

Photon Spectrometer for photons, neutral mesons and -jet tagging l single arm em calorimeter Pb. W 04: Very dense: X 0 < 0. 9 cm Good energy resolution (after 6 years R&D): stochastic 2. 7%/E 1/2 noise 2. 5%/E constant 1. 3% 34 ð dense, high granularity crystals µ novel material: Pb. W 04 ð ~ 18 k channels, ~ 8 m 2 ð cooled to -25 o Pb. W 04 crystal Korea 2004 J. Schukraft

Dimuon Spectrometer l l Study the production of the J/Y, Y', U, U' and U'’ decaying in 2 muons, 2. 4 < < 4 Resolution of 70 Me. V at the J/Y and 100 Me. V at the U RPC Trigger Chambers 5 stations of high granularity pad tracking chambers, over 800 k channels Complex absorber/small angle shield system to minimize background (9035 cm from vertex) Dipole Magnet: bending power 3 Tm Korea 2004 J. Schukraft

Muon Chambers Station 3 -4: Slats Station 1&2: Quadrants Trigger RPC 36 Korea 2004 J. Schukraft

Muon Magnet l Dipole Magnet ð 0. 7 T and 3 Tm ð 4 MW power, 800 tons ð World’s largest warm dipole 37 Korea 2004 J. Schukraft

Computing Phase Transition The Problem: l Online: storing up to 1. 2 Gbyte/s ð whole WWW in few hours on tape ! ð ~ 10 x RHIC ! l Offline: 18 Mega. SI 2000 ð 100, 000 PC's in 2000 (500 Mhz) ð ~ 100 x RHIC !! The Answer: cheap mass market components Industry & Moore's law The Challenge: make 100, 000 mice do the work of one elephant 38 ALICE DC III new computing paradigm: The GRID Korea 2004 J. Schukraft

Data Challenges reduced number of components (PC’s etc. ) available in 2003 reliability of new equipment imperfect 39 Korea 2004 J. Schukraft

ALICE GRID is there: ALIEN OSU/OSC LBL/NERSC Birmingham Dubna NIKHEF Saclay GSI CERN Merida Lyon Torino Padova IRB Bologna Bari Cagliari Yerevan Catania Kolkata, India Capetown, ZA l The CORE GRID functionality exists l Distributed production working, distributed analysis to be done. . . 40 Korea 2004 J. Schukraft

Past-Present-Future l AGS/SPS: 1986 – 1994 ð existence & properties of hadronic phase µ chemical & thermal freeze-out, collective flow, … RHIC l SPS: 1994 – 2003 ð ‘compelling evidence for new state of matter with many properties predicted for QGP’ µ J/Y suppression (deconfinement ? ) µ low mass lepton pairs (chiral restoration ? ) • l RHIC: 2000 - ? ð compelling evidence -> establishing the QGP ? µ parton flow, parton energy loss ð however: soft ~ semihard; lifetime hadron ~ parton phase l LHC: 2007 - ? ? ð (semi)hard >> soft, lifetime parton >> hadron phase ð precision spectroscopy of ‘ideal plasma ‘QGP µ heavy quarks (c, b), Jets, Y, thermal photons LHC: will open the next chapter in HI physics significant step over & above existing facilities 41 THE place to do frontline research after 2007 Korea 2004 J. Schukraft

Summary l LHC is the ultimate machine for Heavy Ion Collisions ð very significant step beyond RHIC ð excellent conditions for experiment & theory (QCD) ð not only latest, but possibly last HIC at the energy frontier l ALICE is a powerful next generation detector ð first truly general purpose HI experiment µ addresses most relevant observables: from super-soft to ultra-hard ð many evolutionary developments µ SSD, SDD, TPC, em cal, … ð some big advances in technology µ electronics, pixels, TOF, computing Heavy Ion Community can look forward to eventually exploit this unique combination ! 42 Korea 2004 J. Schukraft