Stato e prospettive della fisica con fasci nucleari ultrarelativistici. • Di che si tratta? • Perché è interessante? • Alcuni risultati recenti, con commenti sul • Futuro (I): l’esplorazione del diagramma di fase della materia nucleare – SPS (SHINE), RHIC energy scan, FAIR (CBM) • Futuro (II): lo studio del Plasma di Quark e Gluoni (con un bias verso ALICE…) – RHIC upgrade e LHC Paolo Giubellino • LHC: i primi “3 minuti” INFN Torino • LHC: i primi 104, 105, 106 eventi Congresso SIF Bari Ottobre 2009 … un campo di ricerca in espansione! • SPIRES query for all publications with QGP, SQGP, QUARK-GLUON PLASMA, QCD PLASMA, STRONGLY COUPLED PLASMA, STRONGLY-COUPLED PLASMA in their title: "Quark Gluon Plasma" Publications Versus Time

150

100

SPIRESEntries 50

0 1970 1975 1980 1985 1990 1995 2000 2005 2010 Year

• Oggi oltre 200 i fisici italiani coinvolti A bit of history: / 2007 Accelerators 2008 2009 of Heavy Ions 2010 • Experimental programs with High Energy nuclear beams have been carried out for more >1986 than 20 years • After the pioneering work at the Bevalac in the late seventies, 4 facilities at really high energy: AGS, SPS, RHIC and LHC • Two communities joined: • particle physicists • nuclear physicists

•Latest news: first Pb injection in the LHC performed succesfully this weekend! H. Specht, 1992 Very difficult experiments...

central Au-Au event @ ~130 GeV/nucleon CM energy

STAR La fisica Nucleare è molto cambiata…

Eiffel tower ALICE • I progetti sono ~ 7300 tons magnet imprese ~ 8000 tons mondiali di estrema complessità ed enormi dimensioni, che si sviluppano su decenni. Even the “simplest” element requiresAluminum te know from -Armenia how and contribution from all over the world Steel cone from Finland Example: the ALICE Muon Absorber – complex mechanical piece ~ 100 tons ~ 18 m Concrete from France, Engineering & Supervision by CERN Design• byoptimized Russia (Sarov/ISTC) material content Graphite & Steel from India W, Pb, Fe, graphite, Boron, plastic, concrete,.. • carefully chosen Leadgeometry from England – minimize cost via design by factor 2!

• and by worldwide Italian polyethylene Support from Italy bargain hunting Tungsten from China Who is ALICE

~ 1000 Members Spain/Cuba Romania Japan Brazil from both NP and HEP South Africa Korea USA Italy China communities India Croatia Armenia ~30 Countries Ukraine Mexico ~100 Institutes JINR

Russia ~ 150 MCHF capital cost France (+ „free‟ magnet) Netherlands Hungary History UK Greece Germany 1989-1996: Design Sweden Poland Finland Norway CERN 1992-2002: R&D Slovak Rep. Denmark 2000-2010: Construction Czech Rep. 2002-2007: Installation 2008 -> : Commissioning 3 TP addenda along the way: 1996 : muon spectrometer 1999 : TRD 2006 : EMCAL Un decennio di R&D…

In detector Hardware and VLSI Electronics In DAQ & Computing => successfully completed => in progress now across the decade of the 1990's: – scalable architectures with – Inner Tracking System (ITS) consumer electornics • Silicon Pixels (RD19) commercial components • Silicon Drift (INFN/SDI) (COTS) • Silicon Strips (double sided) • low mass, high density interconnects – high perf. storage media • low mass support/cooling – GRID computing – TRD • bi-dimensional (time-space) read-out, on-chip • trigger (TRAP chip) – TPC • gas mixtures (RD32) • advanced digital electronics • low mass field cage – EM calorimeter • new scint. crystals (RD18) – PID • Multigap RPC's (LAA) • solid photocathode RICH (RD26) DOUBLE STACK OF 0.5 mm GLASS Example:Time Of Flight cathode pick up pad Edge of active area Breakthrough after > 5 Resistive layer (cathode) years of R&D 5 gaps Resistive layer (anode) for p, K, p PID anode pick up pad p, K for p <2 GeV/c Resistive layer (anode) 5 gaps p for p <4 GeV/c Resistive layer (cathode) - 0.9 < h < 0.9 cathode pick up pad 150 kchann. full f 2 Multigap Resistive Plate Chambers over ~150 m

1200

1000 STRIP 10 H.V. +- 6 kV

800 s = 53 ps minus 30 ps jitter of timing 600 Typical scintillator = 44 ps 400 time spectrum 200 full size TOF modules under test 0

-1000 -500 0 500 1000 A. Zichichi‟s group Time with respect to timing scintillators [ps] ALICE in 2001 ITS Installation 15.3.07 … in costruzione …

TPC

SPD

SSD/SDD Traversing the TPC Insertion of final TOF super module Installation of final muon chamber

ALICE in 2008

Formal end of ALICE installation July 2008 E tutto questo a che scopo? Early Ideas • Hagedorn 1965: mass spectrum of hadronic states

=> Critical temprature Tc=B • QCD 1973: asymptotic freedom Quantum Chromo Dynamics (QCD) is the theory that describes the interactions between – D.J.Gross and F.Wilczek, H.D. Politzer quarks and gluons [Nobel Prize 2004] • 1975: asymptotic QCD and deconfined quarks and gluons – N. Cabibbo and G. Parisi, J. Collins and M. Perry Interpretation of the Hagedorn temperature as a phase transition rather than a limitingT: “We suggest … a different phase of the vacuum in which quarks are not confined” First schematic phase diagram (Cabibbo and Parisi, 1975) Ma se la forza cresce con la distanza, a piccole distanze è piccola (libertà asintotica) Idea: ottenere il deconfinamento usando collisioni di Nuclei => compresssione e riscaldamento

Il sistema si espande e si raffredda, e si ricostituiscono gli adroni ordinari…. Come nell'evoluzione dell'Universo primordiale! Exploring the QCD phase diagram T.D. Lee (1975) “it would be interesting to explore new phenomena by distributing a high amount of energy or high nuclear density over a relatively large volume “ How? Colliding nuclei at very high energy Complex picture, with many features

quark-gluon plasma (QGP) Tc Early universe c-symmetric

hadron gas c- Symmetry Broken

Temperature Colour super nucleon gas nuclei conductor neutron stars net baryon density r0 Phase diagram for H2O Critical endpoint Lavori di Beppe Nardulli Study how collective phenomena and macroscopic properties of strongly interacting matter emerge from fundamental interactions Il Big Bang …

Fino a 11 milionesimi di secondo dopo la sua nascita, tutta la materia dell’Universo è colorata: quark e gluoni si muovono liberamente. Quando l’Universo si è raffreddato fino a circa 1012 K, diventa incolore: quark e gluoni sono emprigionati per sempre negli adroni, di cui non ci restano oggi che i protoni e i neutroni. Nelle collisioni nucleari ad altissima energia, si percorre prima il cammino inverso, per poi ripercorrere quello dell'Universo...

Il terreno di studio Il Little Bang 1. I nuclei accelerati si Laboratoire scontrano frontalmente

2. L’energia della collisione si materializza sotto forma di quark e gluoni 3. I quark e i gluoni interagiscono sotto l’effetto dell’interazione forte: la materia tende all'equilibrio

4. Il sistema si diluisce e si raffredda

5. Quark e gluoni si t~10-24-23s t~10 s condensano formando T~5×101212 K v/c = 0,99999993 T~10 K degli adroni Contrazione di Lorentz : 7 fm  0,003 fm QCD • How does one get predictions from QCD? – Non perturbative methods • Lattice simulations (great continuous progress) • Effective lagrangians – Chiral lagrangians – Heavy quark effective theories – AdS/CFT correspondence – ..... • QCD sum rules • Potential models (quarkonium) – Perturbative methods • Based on asymptotic freedom, still remains the main quantitative connection to experiment.... Unfortunately so far (pre-LHC) little applicability to HI collisions Lattice QCD predicts a rapid transition, with correlated deconfinement and chiral restauration Energy density increases sharply by the latent heat of deconfinement Tc = 173 ± 12 MeV

ec = 700 ± 200 MeV/fm3 for the (2 + 1) flavor case: the phase transition to the QGP and its parameters are quantitative predictions of QCD. Summary of recent results

on Tc from lattice QCD Different approaches show consistent results.

From F. Karsch 2008 Temperatura ~ 170 MeV

• Quanto è caldo? 100,000 volte la temperatura al centro del Sole! QGP signatures (?)

• There are no golden observables proving the existence of the QGP… the word “signature” is even no longer used • We had few predictions at the start of the HI experimental programme: Essentially – quarkonium suppression Matsui, Satz (1986) – strangeness enhancement Rafelski, Müller (1982)

• Use all the experimental tools to probe the evolution of the collision (formation time, thermalization time, collective effects, hard probes,…) • There is now a strong circumstantial evidence of a coloured partonic medium, which is produced early and expands as an almost ideal liquid What do we measure? Language • We all have in common basic nuclear properties – A, Z … • But some are specific to heavy ion physics

– v2 Fourier coefficient of azimuthal anisotropies “flow”

– RAA 1 if yield = perturbative value from initial parton-parton flux – T Temperature (MeV)

– mB Baryon chemical potential (MeV) ~ net baryon density 3 – h Viscosity ( MeV ) indirectly inferred from RAA and v2 – s Entropy density ~ “particle” density

dET 1 dET – e Energy density (Bjorken 1983): ε   2 ATdz πR τ dy Collision Geometry In these complicated events, we have (a posteriori ) control over the event geometry: Centrality  impact parameter (b) spectators selection on collision geometry z

“peripheral” => b ~ bmax “central” => b ~ 0

For a given b, Glauber model participants: gives Npart nucleons in y and Nbin coll nuclear overlap x spectators 1 2 3 4 Measured with Zero Degree Calorimeters Detecting the spectator nucleons ZP ~ 100m away from theinteraction point Or via transverse energy / part. multiplicity ZN Reaction Plane reaction plane resolution

multiplicity in ALICE central detector Space-time Evolution of the Collisions p time g e f jet K p m L g e Freeze-out (~ 10 fm/c) (no more elastic collisions) Hadronization particle composition is fixed (no more inel. Collisions) QGP (~ few fm/c)

Hard Scattering + Thermalization space (< 1 fm/c)

Pb Pb

Gli Esperimenti @2000: 25 countries, HI experiments at the SPS about 500 physicists involved strangeness, hadron spectra, large acceptance Ongoing!

2009 NA61 (SHINE) muons

multistrange electrons NA60 2000 strangeness, NA49 NA57 exotics hadron spectra photons Pb NA50 NA52 WA97 NA45 WA98 1994 (Ceres) NA44 muons NA34/3 WA94 (Helios-3) strangeness S NA35 NA36 WA85 NA34(Helios-2) NA38 WA80 1986 HADRONS LEPTONS, PHOTONS SPS highlights • Strangeness enhancement due to chiral symmetry restoration predicted in 1982 (Rafelski, Müller) + stronger enhancement for multistrange particles due to recombination in 1986 (Koch, Müller, Rafelski) • Observed by WA97 and NA57 at the SPS • J/y suppression in AA collisions due to Debye screening predicted in 1986 (Matsui, Satz) • observed by NA50 and NA60 experiments at the SPS

The claim of having observed a new state of matter compatible with the QGP was largely based on these two experimental findings 33 4 Experiments, ~ 1000 people from Experiments at RHIC ~ 100 Institutes Both running (energy scan) in ~ 20 Countries STAR and being upgraded • Hadronic Observables PHENIX • Large Acceptance (TOF, HBD, Vertex dets) • Leptons, Photons, & Hadrons

BRAHMS PHOBOS 95° Inclusive Particle Production, Charged Hadrons, Large Rapidity Range Particle Correlations 30° 2.3° Both completed 30° 15° And elsewhere…

• GSI: – A very lively program ongoing at SIS (FOPI, KaoS, HADES) – A rich future: FAIR (CBM) • 100*SPS beam intensity • DUBNA – NICA HI collider The High Energy frontier: the Large Hadron Collider LHC 27 km circumference 4 Experiments ~ 100 m underground Energy 14,000 GeV (pp) Lake Geneva CMS

LHCb

ALICE ATLAS LHC as an Ion Collider • Running conditions for „typical‟ Ion year:

Collision √sNN L0 /L0 Run time σinel system (TeV) (cm-2s-1) (%) (s/year) (b)

PbPb 5.5 1027 70-50 106 * * 7.7

** ∫ L dt ~ 0.5 nb-1/year A x28 jump in energy as compared to RHIC • Running plan: – First short low-luminosity run (~1/20th design, i.e. L ~5x1025 cm-2s-1) • late 2010 (confirmed) – Following few years (1HI „year‟ = 106 effective s, ~like at SPS) • 2 - 3 years Pb-Pb : targeting integrated L ~1nb-1 L ~ 1027 cm-2s-1 • 1 year p - Pb „like‟ (p, d or a ) L ~ 1029 cm-2s-1 • 1 year light ions (eg Ar-Ar) L ~ few 1027 to 1029 cm-2s-1 – Later: different options depending on Physics results LHC vs RHIC • Unexplored low x regime. • Energy density and QGP lifetime increase by a factor 2 ÷3

• But also new probes: Jets, Heavy Quarks HI Experiments at the LHC • One dedicated Heavy-Ion experiment: ALICE – Needs to cover essentially all relevant observables – Designed to be able to cope with the highest multiplicities – The design evolved with time (latest addition: EMCAL) – Now over 1000 Physicists from 100 Institutions in 30 Countries • CMS and, to a lesser extent, ATLAS progressively expanded their interest in the Heavy-Ion runs – Very healthy competition! – Now about 150 Physicists involved ALICE is different… • What makes ALICE different from ATLAS, CMS and LHCb ? – Experiment designed for Heavy Ion collision • only dedicated experiment at LHC, must be comprehensive and be able to cover all relevant observables • VERY robust tracking – high-granularity detectors with many space points per track, very low material budget and moderate magnetic field

• PID over a very large pT range • Hadrons, leptons and photons

• Very low pT cutoff • Excellent vertexing • Complementary to the other experiments Experimental Constraints from the Heavy Ion running

– extreme particle density (dNch/dh ~ 2000 – 8000) • x 500 compared to pp @ LHC

– large dynamic range in pT: • from very soft (0.1 GeV/c) to fairly hard (100 GeV/c) – lepton ID, hadron ID, photon detection – secondary vertices – modest Luminosity and interaction rates • 10 kHZ (Pb-Pb) to 300 kHZ (pp) (< 1/1000 of pp@1034) Tracking challenge

Excellent tracking + vertexing + PID capabilities are the key factors

With part of the event removed, displaced vertices can be seen -  Lp - ALICE Experimental Solutions

• dNch/dh: high granularity, 3D detectors (560 million pixels in the TPC alone, giving 180 space points/track, largest ever: 88m3), large distance to vertex (use a VERY large magnet )

– emcal: high-density crystals of PbWO4 at 4.6 m (typical is 1-2 m !)

• pt coverage: thin det, moderate field (low pt), large lever arm + resolution (large pt) 2 – ALICE: < 10%X0 in r < 2.5 m (typical is 50-100%X0), B= 0.5T, BL ~ like CMS ! • PID: use of essentially all known technologies – dE/dx, Cherenkov & transition rad., TOF, calorimeters, muon filter, topological • rate: allows slow detectors (TPC, SDD), moderate radiation hardness The ALICE detector

Size: 16 x 26 meters Weight: 10,000 tons ALICE Design Performance

TPC acceptance = 90%

Low material budget low pt cut off Momentum resolution ~ 5% @ 100 GeV/c

PID Impact parameter resolution < 60 mm (rf)

for pT > 1 GeV/c

+ decay topologies ((K0, K+, K-, L f D) K and L beyond 10 GeV/c RHIC results and the Future

• Active since year 2000 at BNL • Up to √s=200 GeV/A (w.r.t. 17 GeV/A at the SPS) in Au-Au, d-Au, Cu-Cu and p-p collisions

• RHIC results in a nutshell: we have entered the era of thermodynamics of strongly interacting systems • The colliding nuclei at RHIC are CGC (saturation) • The matter produced at RHIC shows strong collective motion and evidence for hydrodynamic behavior with very small viscosity. Flow builds up at the partonic level • The matter produced at RHIC is opaque to hard probes Multiplicities@RHIC • Much lower than expectations support saturation models

QCD Saturation Physics: QCD at the highest parton densities qualitatively novel regime of QCD, in which Parton densities are maximal while the coupling constant is small LHC, Physics of „The First 3 Minutes‟: Multiplicity First estimate of energy density Saturation, CGC ? integrated multiplicity distributions from Au- Au/Pb-Pb collisions and scaled pp collisions

dNch/dy = 2600 saturation model Eskola hep-ph/050649

dNch/dy = 1200 ln(√s) extrapolation Before RHIC, predictions for the LHC were considerably higher, ranging up to

dNch/dy=8000 Chemical composition Particle composition can be described in terms of a statistical model (grand canonical ensemble) with 2 free parameters (thermalization temperature and bariochemical potential).

Consistent with a thermalization of the system with T ~ 170 MeV , mB ~ 30 MeV Limiting temperature reached for large sqrt(s). First data at LHC will check if the hypothesis survives at *20 the RHIC cm energy Parametrization of all freeze- out points • If the fit parameters are plotted vs. Sqrt(s), a limiting T emerges at about 160 MeV • First data at LHC will check if the hypothesis survives at *20 cm energy => “DAY 1 PHYSICS” 0 ALICE Pilot run Physics: r f,K* ,K s, L  …

Measure: 106 central Pb-Pb • strangeness production • medium modification of mass and widths L 107 events: Reconstruction rates: pt reach f,K,L L: 13/event ~ 13-15 GeV : 0.1/event p reach  : 0.01/event t p : 1 to 3-6 GeV ~ 9-12 GeV T

r0(770) p+p- 106 central Pb-Pb

Mass resolution + - ~ 2-3 MeV f (1020) K K

106 central Pb-Pb Freezeout and phase diagram finally being populated with data points!

NB, measures the T at the hadronization time Statistical model parameters:  Chemical freezeout temperature (T) Bariochemical potential (mB) can be plotted on the phase diagram

For low values of mB (high sqrt(s)) the temperatures of the chemical freezout approach the ones calculated for the phase transition. Limiting temperature? Critical point search Theory searches need to cover a broad region of phase diagram Key idea: study Phase Diagram throughout energy scan region Turn-off major sQGP signatures already established at top RHIC energies? Quark number scaling Hadron suppression Pair correlations in ∆φ&∆η Parity violation vs. √sNN 1st-order Phase Tran. / Critical Point Elliptic & directed flow Azimuthally-sensitive HBT Fluctuations & correlations Kurtosis analysis on net proton

Gang Wang (UCLA) QM2009 RHIC Critical Point Search Program

Hadron Mass

200 GeV

62.4 GeV Beam Energy Beam

9.2 GeV (Test run in 2008)

Uniform acceptance for different particle species and for different beam energies in the same experimental setup (advantage over fixed traget expt.) New Program : SPS - SHINE A significant difference between freeze-out and transition temperature can lead to dilution of the signatures of the QCD critical point. One way address this is to vary system size/colliding ion size.

F. Becattini et al., PRC 73, 044905 What is the difference vs. NA49 ? Experimental set up : New spectator calorimeter for centrality selection Forward Time-Of-Flight Beam pipe TPC readout speed Physics Program : Studying QCD Critical Point and Onset of various observations with varying colliding ion size, collision centrality and having a proper p+p baseline New Program : FAIR - CBM

CBM at SIS 300 will start in > 2017 Claudia Hoehne 10-45A GeV beam energy, high availability of beam (order of 10 weeks per year), interaction rates up to 10 MHz “CBM light” at SIS 100 in ~ 2015 Au beam up to 11A GeV, p beam up to 30 GeV (multistrange hyperons, charm production in pA)

Assume 10 weeks beam time, 25A Gev Au+Au (minbias), no trigger, 25 kHz interaction (and storage) rate: • “unlimited statistics” of bulk observables, e.g. ~1010-11 kaons, 1010 Λ High luminosity, • low-mass di-electrons with high statistics, 106 r  f -mesons (each) rare probes, • multistrange hyperons with high statistics, higher mB reach 108 , 106  Example of CBM performance: • Simulation of open charm reconstruction • STS – 8 double-sided Si micro-strip sensor stations (each 400 mm Si equ.) • MVD – 2 MAPS pixel sensors (300 mm, 500 mm) at z = 5 cm, 10 cm • no K, p id.; p rejection via TOF; 2ndary vertex resolution ~ 50 mm

D0 → K π, cτ= 123 μm D → K π π, cτ= 317 μm 1010 centr. ev. 109 centr. ev. eff = 4.4% eff = 2.6% _ S/B = 6.4 (D0) S/B = 2.4 (D-) 2.1 (D0) 1.1 (D+)

1012 minbias events ~ 7k D + 20k D + - 25A GeV Au+Au 0 0 ~ 12k D + 26k D

Claudia Höhne Quark Matter 2009, Knoxville 57 Summary of Phase diagram exploration • Lattice and other QCD based models :

– mB = 0 - Cross-over

– TC ~ 170-195 MeV

– mB > 160 MeV - QCD critical point • No signatures of QCD critical point established, possible hints at SPS T. Andrews. Phil. Trans. Royal Soc., 159:575, 1869

Critical Opalescence as observed in CO liquid-gas transition 2 T > TC T~TC T < TC SCIENCE Vol: 298 Elliptic flow 2179 (2002) 7Li

Elliptic flow coefficient

dn/df ~ 1 + 2 v2(pT) cos (2 f) + ... Where azimuth is measured z y w.r.t. the reaction plane x Flow: Correlation between coordinate and momentum space => azimuthal asymmetry of interaction region trasported to the final state close particles move at similar velocity and direction flow builds up in an interacting medium with pressure gradient for given boundary conditions, flow 2v2 profile depends on Equation of State EoS and viscosity h of „fluid‟ Hydrodynamics of perfect liquid: h = 0, l = 0 („strongly interacting‟) Ultra-cold 7Li Flow acts at early times 10-12 eV , 2 ms of expansion Flow “knows” quarks…

baryons

mesons

2 2 KET  m + pT - m The fluid is strongly interacting => small viscosity

• Although the errors are large (especially from assumptions on initial spatial distribution: Glauber vs. CGC) the data rule out values of h/s much larger than 1/4p, the conjectured limit from AdS/CFT • Also measured from fluctuations, heavy quark motion,... • Most perfect liquid ever observed? Summary of Viscosity / entropy density

Most of the estimates are below Helium at critical temperature.

Gang Wang (UCLA) QM2009 LHC, day 1 (105 events) : is the QGP an ideal fluid ?

LHC ?

• One of the first answers from LHC – Hydrodynamics: modest rise – Experimental trend & scaling predict large increase of flow Hard Scattering as a Probe New for heavy ion physics  Hard Parton Scattering ~ impossible at SpS, interesting at RHIC, perfect at LHC • Jets leading particle

 high pt leading particles hadrons  azimuthal correlations  jets in calorimeters

hadrons • Scattered partons propagate through matter leading particle radiate energy (~ few GeV/fm) in colored medium

• suppression of high pt particles called “parton energy loss” or “jet quenching” • alter di-jets, azimuthal correlations, jet fragmentation function An “old” idea returns.... Bjorken’s original estimate and its correction

Bjorken 1982: consider jet in p+p collision, hard parton interacts with underlying event collisional energy loss dE dL 10GeV fm (Bjorken realized later that this estimate coll was numerically erroneous.) Bjorken conjectured monojet phenomenon in proton-proton



Today we know (th): radiative energy loss dominates

2 Baier Dokshitzer Mueller Peigne Schiff 1995 Erad  asqˆ L

• p+p: L  0.5 fm, Erad 100 MeV Negligible ! Monojet phenomenon! • A+A: L  5 fm, Erad 10 GeV



 Jet quenching: a true pQCD prediction Observations: The Matter is Opaque  STAR azimuthal correlation function shows ~ complete absence of “away-side” jet

GONE

F = p

F Partner in hard scatter is completely absorbed in the dense medium F=0 F = 0 Suppression of high-pT hadrons: Definition of RAA Control

• Final State Suppression / Initial State Enhancement!

Au + Au Experiment d + Au Control Experiment

Final Data Preliminary Data Control: Photons shine, Pions (and h) don‟t

• Direct photons are not inhibited by hot/dense medium • Rather: shine through consistent with pQCD Issues…

Eskola, Honkanen, Salgado, Wiedemann NPA747 (2005) 511, hep-ph/0406319

• The quenching is anomalously large GeV 2 (I.e. exceeds the perturbative estimate by ~ 5) qˆ ( t 1 fm /c)  5  5qˆ pert To fit it, must assume very large cross sections fm QCD … while it comes naturally in calculations based on the AdS/CFT correspondence

 Fluid Effects on Jets ?  Mach cone? ☑ Jets travel faster than the speed of sound in the medium. ☑ While depositing energy via gluon radiation.

QCD “sonic boom” (?)

To be expected in a dense fluid which is strongly-coupled

W.A. Zajc High pT Parton  Low pT “Mach Cone”?  The “disappearance” is that of the

high pT partner

 But at low pT, see re-appearance

 and

 “Side-lobes” (Mach cones?)

07-Jun-07 W.A. Zajc LHC vs RHIC hard probes

From RHIC to LHC

• Cross section for heavy flavours and jets grows by:

scc → ~ 10 sbb → ~ 100 sjet>100GeV → ~ ∞ sRHIC(→ll) ~ sLHC (Z→ll)

N(qq) per central PbPb collision

SPS RHIC LHC charm 0.2 10 200 LHC is a Hard bottom - 0.05 6 Probes Machine! LHC: the realm of Jets Jet statistics in pilot Pb run Jets are produced copiously…

2 20 100 200 pt (GeV) 100/event 1/event 103 in first 106 Pb-Pb events

ALICE Acceptance 106 central PbPb collisions

410 1068central central Pb PbPb-Pb eventscollisions (pilot (month) run) ET Njets threshold 4 1.56 10 105 3eventsevents 50 GeV 5  10 100 GeV 1.5  103 150 GeV 300 200 GeV 50 First full run Physics: D0  K-p+ A major ALICE asset: measure Y, B, J/y and D in the same experiment: natural normalization, Bkgd subtraction, in central region identify J/y from B decays

• Golden channel for open charm • S/B ≈ 10% • Significance for 1 month Pb-Pb run (107 events) : S/√(S+B) ≈ 40

statistical.

systematic. HI Physics with ALICE, summary

 fully commissioned detector & trigger  early ion scheme  alignment, calibration available from pp  1/20 of nominal luminosity  first 105 events: global event properties  ∫Ldt = 5·1025 cm-2 s-1 x 106 s  multiplicity, rapidity density 0.05 nb-1 for PbPb at 5.5 TeV  elliptic flow 8 NPbPb collisions = 4·10 collisions  first 106 events: source characteristics 400 Hz minimum-bias rate  particle spectra, resonances 20 Hz central (5%)  differential flow analysis  muon triggers:  interferometry ~ 100% efficiency, < 1kHz 7  first 10 events: high-pt, heavy flavours  centrality triggers:  jet quenching, heavy-flavour energy loss bandwidth limited  charmonium production 7 NPbPbminb = 10 events (10Hz) 7  yield bulk properties of created medium NPbPbcentral = 10 events (10Hz)  energy density, temperature, pressure  heat capacity/entropy, viscosity, sound velocity, opacity  susceptibilities, order of phase transition ALICE è pronta? 2008 Detector Configuration • fully installed & commissioned – ITS, TPC, TOF, HMPID, – MUON spectrometer, – V0, T0, FMD, ZDC, ACORDE – DCS • partially completed – DAQ 40% ) completed 2009 – HLT (20%) completed 2010 – TRD (25%) completed 2010 – PHOS (20%) completed > 2011 – PMD (20%) completed 2009 – EMCAL (0%) completed 2011 • at start-up full hadron and muon capabilities • partial electron and photon capabilities ALICE 2007/2008 runs 2007 2008 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct

st nd 3rd global run 1 global run 2 global run st 10-21 Dec 4 Feb-9 Mar 5 May – 20 Oct 1 Circulating beam First particles from 10 Sep Injection tests machine 15 Jun 8 Aug, 24 Aug Installation&Commissioning 24/7 operation Cumulated amount of data readout from detectors 14 detectors ran 515 days datataking standalone and in 3 PB read-out global runs: ~350 TB recorded to tape in total SPD, SSD, SDD, TPC, TRD, TOF, MCH, MTR, HMP, Global runs FMD, V0, T0, ACO, ZDC DAQ, DCS, Trigger & HLT operational Cosmics! Event Displays TRD TOF ACO and TPC

Muon spectrometer SDD + SPD

TPC and TRD triggered by TRD L182 SSD: p-n charge correlation Calibrations…

SSD: S/N ~ 40

SDD: Drift speed constant for hours

TPC Krypton Gain Calibration

Laser tracks in TPC

SDD: Drift speed calibration vs postion TPC performance Results from cosmics B=0.5 T (7 million events) dE/dx resolution (PPR goal: ~ 5.5%) Measured 5.7 % p resolution (PPR goal: ~ 5% @ 10 GeV) t Transverse Momentum measured ~ 6.5% @ 10 GeV with partial Resolution calibration (partially calibrated) (was 10% in October 2008)

Particle Identification ITS Alignment

Track-to-track (top vs bottom) Track-to-“extra clusters” distance distance in transv. plane in transv. plane (sensor overlap)

before before alignment alignment after after alignment alignment

s = 55 mm (vs 40 mm in simulation s = 21 mm (vs 15 mm in simul. without misalignment) without misalignment)

• After realignment with cosmics using SPD triggered data and Millepede: • Residual misalignment < 10 µm • Detector position resolution r 12 µm TOF Calibrations with cosmics very promising despite low statistics (10K tracks) and many 10,000 calibration parameters

Trigger fully functional Noise rate better than expected

Very preliminary Single hit resolution σ 190/√2 = 130 ps (goal: < 100 ps)

TPC extrapolated tracks – space resolution TPC-HMPID track matching Muon Chamber noise < 2 ADC counts (w/o alignment)

TRD cosmic event

HMPID cosmic event August 2008 Beam on collimator Beam in LHC SPD self trigger timing exercises etc…

200000 y = 3.5326x - 12525 180000

160000

140000

120000

Series1 100000 Linear (Series1)

80000 FMD multiplicity FMD 60000 40000 FMD hits versus SPD hits 20000 (beam through ALICE) 0 0 10000 20000 30000 40000 50000 60000 ITS multiplicity

V0

FMD

Beam through Alice Secondaries produced in monitoring screens ZDC First Interaction in ALICE • LHC beam circulation tests on 11.09.2008. • Collision of beam-halo particle with SPD: 7 reconstructed tracks from common vertex. In 2008 ALICE was ready for data...

• So, how did we use the extra time? – Install progressively more detector elements • EMCAL, TRD, PHOS, PMD • add capacity to DAQ (40% => 100%) and HLT (20% => 60%) – Reorganize services to improve the accessibility for future maintenance, improve cooling, consolidate infrastructure… – Work on the cosmic data of 2008 to tune the software and prepare for the data analysis (alignment, calibration, …) – Continue work on simulations to be ready for first Physics The Miniframe leaving for refurbishing… EMCAL modules coming in… s 11% E ~ E E ALICE 2009 Complete: ALICE Status ITS, TPC, TOF, HMPID, FMD, T0, V0, ZDC, Muon arm, Acorde PMD , PHOS(3/5), DAQ

Partial: 2/3 HLT 7/18 TRD 4/12 EMCAL 11-12 July 09 LHC extraction test: Back in Business! Single –bunch 0.4x 1010 p each and 12-bunch trains (25 9 SDD ns apart) with 25 x 10 particles per bunch Very busy day: trigger timing (MTR, SPD, V0, T0), FMD calibr, gate adjustments, SDD delay tuning FMD ZNC_TC

ZPC_TC Gate from Pixel trigger ZDC

SPD

Muon trigger chambers Conclusioni

• Lo studio delle collisioni di ioni ultrarelativistici ha portato un ricco raccolto di risultati scientifici, spesso inattesi • Ci prepariamo a un nuovo salto di qualità nella comprensione delle interazioni forti a grandi densità e temperature • E’ un momento di grandi opportunità, e gli esperimenti sono pronti a sfruttarle al meglio.