the alice experiment at lhc: detector & physics

The ALICE Experiment at LHC:The ALICE Experiment at LHC:Detector & PhysicsDetector & Physics

V. ManzariV. Manzari

INFN & University of Bari - ItalyINFN & University of Bari - Italy

XI Frascati Spring School “Bruno Touschek”LNF, May 15th – 19th, 2006

Vito Manzari/INFN BariVito Manzari/INFN Bari Frascati Spring School, May 15th -19th, 2006Frascati Spring School, May 15th -19th, 2006 22

ContentsContents

Nucleus-nucleus collisions at the LHCNucleus-nucleus collisions at the LHC The Alice experimentThe Alice experiment Overview of Alice subsystemsOverview of Alice subsystems Physics ExamplesPhysics Examples

– Jet quenching Jet quenching – Heavy flavoursHeavy flavours

ConclusionsConclusions


QCD tells us…QCD tells us…

Tc 173 MeV, mq0, Nf=2,3 Order of the transition? c 0.3-1.3 GeV/fm3

Ultimate goal: Ultimate goal: understanding of the QCD phase diagramunderstanding of the QCD phase diagram- QCD prediction - QCD prediction the existence of a new state of matter at the existence of a new state of matter at

high temperature, the quark Gluon Plasma high temperature, the quark Gluon Plasma

LHC will allow to go much deeper into a QGP phase and to study LHC will allow to go much deeper into a QGP phase and to study the QGP equation of state.the QGP equation of state.


SPS to RHIC to LHCSPS to RHIC to LHC

<0.2~0.5~10 (fm/c)

4–101.5–4.0<1QGP (fm/c)

2x1047x103103Vf(fm3)

15–404–52.5 (GeV/fm3)

2–8 x 103850500dNch/dy

550020017s1/2(GeV)

LHCRHICSPSCentral collisions

Formation time LHC ≈ 1/3 x RHIC

QGP lifetime LHC ≈ 3 x RHIC

Initial energy density LHC ≈ 3 10 x RHIC Volume LHC ≈ 3 x RHIC

Initial condition at LHC different than at RHIC: “hotter – bigger – longer lived”

QGP is characterized by two qualitatives changes: deconfinement & chiral simmetry restoration

Both changes will certainly have consequences in the final state observed by the experimental apparatus

Energy per NN LHC ≈ 30 x RHIC


Novel aspects… soft processesNovel aspects… soft processes

The energy increase at LHC will The energy increase at LHC will make accessible a novel range make accessible a novel range of Bjorken-xof Bjorken-x

- solid lines - solid lines relevant x-M relevant x-M22

ranges for particle productionranges for particle production

Probe initial partonic state in a Probe initial partonic state in a “new” Bjorken-x range (10“new” Bjorken-x range (10-3-3 - 10- 10--

55):):

- nuclear shadowing- nuclear shadowing- high-density saturated gluonhigh-density saturated gluon

distribution (CGC)distribution (CGC)

Energy increase Energy increase lower x lower x RHIC forward region RHIC forward region LHC mid rapidity (easier LHC mid rapidity (easier

detection)detection)


Novel aspects… hard processes Novel aspects… hard processes Hard processes contribute Hard processes contribute

significantly to total AA significantly to total AA cross-section: cross-section:

((σσhardhard//σσtottot = 98%) = 98%)

Bulk properties Bulk properties dominated by hard dominated by hard processesprocesses

Hard probes abundantly Hard probes abundantly producedproduced

Hard processes are Hard processes are extremely useful tools:extremely useful tools: Probe matter at very early Probe matter at very early

timestimes Hard processes can be Hard processes can be

calculated by pQCDcalculated by pQCD

Heavy quarks and Weakly Heavy quarks and Weakly interacting probes become interacting probes become accessible (Zaccessible (Z00, W, W±±))

5500 GeV


LHC as Ion ColliderLHC as Ion Collider Running conditions: Running conditions:

Expected Pb-Pb luminosity Expected Pb-Pb luminosity rather low minimum-bias rather low minimum-bias interaction rate (≈8kHz):interaction rate (≈8kHz):

- LHC detectors in heavy ion mode - LHC detectors in heavy ion mode lower rates & higher particle lower rates & higher particle densitydensity

+ other collision systems:+ other collision systems: pA, lighter ions (Sn, Kr, Ar, O) & energies (pp @ 5.5 pA, lighter ions (Sn, Kr, Ar, O) & energies (pp @ 5.5 TeV)TeV)

Collision Collision systemsystem

PbPbPbPb

pppp

<L>/L<L>/L00

(%)(%)

101077

Run timeRun time

(s/year)(s/year)

geomgeom

(b)(b)

LL00

(cm(cm-2-2ss-1-1))

√√ssNNNN

(TeV)(TeV)

0.070.07101034 34 ** 14.014.0

70-5070-50 10106 6 **** 7.77.7101027275.55.5

*Lmax (ALICE) = 1031 ** Lint (ALICE) ~ 0.7 nb-1/year

Vito Manzari/INFN Bari

Frascati Spring School, May 15th -19th, 2006

8

One dedicated HI experiment: ALICETwo pp experiments with HI program:

ATLAS and CMS


Adopted a variety of experimental techiniques

AA Physics Menu at LHCAA Physics Menu at LHC Global propertiesGlobal properties

– Multiplicities, Multiplicities, ηη distributions, zero degree energy distributions, zero degree energy Event historyEvent history

– HBTHBT– Resonance decaysResonance decays

Fluctuations and critical behaviourFluctuations and critical behaviour– Event-by-event particle composition & spectroscopyEvent-by-event particle composition & spectroscopy– Neutral to charged ratioNeutral to charged ratio

Degrees of Freedom vs TemperatureDegrees of Freedom vs Temperature– Hadron ratios and spectraHadron ratios and spectra– Dilepton continuumDilepton continuum– Direct photonsDirect photons

Collective effectsCollective effects– Elliptic flowElliptic flow

Deconfinement, chiral simmetry restorationDeconfinement, chiral simmetry restoration– Charmonium, bottonium spectroscopyCharmonium, bottonium spectroscopy– (Multi-)strange particles(Multi-)strange particles

Partonic energy loss in QGPPartonic energy loss in QGP– Jet quenching, high pJet quenching, high pTT spectra spectra– Open charm and beautyOpen charm and beauty

ALICE Detector Large acceptance Good tracking capabilities Selective triggering Excellent granularity Wide momentum coverage PID of hadrons and leptons Good secondary vertex reconstruction Photon detection


ALICE is a general purpose experiment designed to study the physics of strongly interacting matter and the quark-gluon plasma in nucleus-nucleus collisions.

ALICE will meet the challenge to measure flavour content and phase-space distribution event-by-event at the highest particle multiplicities anticipated for Pb-Pb collisions:

• Most (2 * 1.8 units ) of the hadrons (dE/dx + TOF), leptons (dE/dx, transition radiation, magnetic analysis) and photons (high resolution EM calorimetry).

• Track and identify from very low pt (< 100 MeV/c; soft processes) up to very high pt (>100 GeV/c; hard processes).

• Identify short lived particles (hyperons, D/B meson) through secondary vertex detection.

• Identify jets.

ALICE: The dedicated HI experimentALICE: The dedicated HI experiment


Solenoid magnet 0.5 T


Central Solenoid: from L3 (LEP)Central Solenoid: from L3 (LEP)


Central tracking & PID system:• ITS •TPC• TRD• TOF


||<0.9:B = 0.4 T

TOF(3.7 – 4 m)

TRD(2.9 - 3.7 m)

TPC(85 - 250 cm)

ITS(4 -45 cm)with: - Si pixel - Si drift - Si strip

Central Tracking & PIDCentral Tracking & PID


Combined momentum resolutionCombined momentum resolution

at low momentum dominated by

- ionization-loss fluctuations- multiple scattering

at high momentum determined by

- point measurement precision- alignment & calibration (assumed ideal here) resolution ~ 7% at 100 GeV/c

excellent performance in hard region!


Inner Tracking System (ITS)Inner Tracking System (ITS)

longitudinal coverage:|| < 1 (tracking), ||<2

(multiplicity)


ITS: Silicon Pixel Detector (SPD)ITS: Silicon Pixel Detector (SPD)

2 layers, r = 3.9, 7.6 cm 2 layers, r = 3.9, 7.6 cm sensitive length (in z): sensitive length (in z):

28.6 cm (for both layers)28.6 cm (for both layers) hybrid (bump-bonded) silicon hybrid (bump-bonded) silicon

pixel assembliespixel assemblies Pb/Sn bumpsPb/Sn bumps pixel size: 50 pixel size: 50 × × 425 µm425 µm22

binary r/obinary r/o module size: 12.8 module size: 12.8 ×× 69.6 mm 69.6 mm22

240 modules240 modules 9.8 M channels9.8 M channels

Chip

Sensorbump-bonded assembly

Chip (150 µm thickness)

Sensor (200 µm thickness)

bump-bonded assembly

Picture of a solder bump bond (courtesy of VTT)


ITS: Silicon Pixel Detector (SPD)ITS: Silicon Pixel Detector (SPD)

successful system beam test successful system beam test

Oct. ’04Oct. ’04including full FEE and DAQ, DCS, ECSincluding full FEE and DAQ, DCS, ECS

Combined with the other ITS Combined with the other ITS detector systemsdetector systems

bump bonding at VTT (Finland)bump bonding at VTT (Finland)– series production started (series production started ( > 99%) > 99%)

low-mass support/cooling low-mass support/cooling sectors sectors

readyready assembly sites in Bari and assembly sites in Bari and Padova Padova

StatusStatus– “ “ready for installation”: Nov ‘06ready for installation”: Nov ‘06– viable schedule, but tight & little viable schedule, but tight & little

contingencycontingencyHalf-Barrel final assembly

The Half Cylinders and their tooling

Front view


SPDSPD

Sector 0 (mixed bus)

Sector 1 (full Al bus)


ITS: Silicon Drift Detector (SDD)ITS: Silicon Drift Detector (SDD) Hybrids : Hybrids :

– 520 needed; production completed; 520 needed; production completed; done in industrydone in industry

Modules: Modules: – 260 needed;260 needed;

assembly completed: June ‘06assembly completed: June ‘06 Ladders:Ladders:

– 36 needed; production ongoing36 needed; production ongoing

assembly completed: July ‘07assembly completed: July ‘07 MechanicsMechanics

– Components ready for assemblyComponents ready for assembly

Status:Status:- ready for integration with SSD: Jul ‘06- ready for integration with SSD: Jul ‘06

View of modules with two hybrids;Was used in 2004 beam test


ITS: Silicon Strip Detector (SSD)ITS: Silicon Strip Detector (SSD)

Production:Production:– sensors from three vendors under sensors from three vendors under productionproduction–FEE electronics: all chips in productionFEE electronics: all chips in production– micro-cables & hybrids (Ukraine): micro-cables & hybrids (Ukraine):

very advanced technologyvery advanced technology

Assembly:Assembly:– shared between 4 ( later 5) sites (Finland, shared between 4 ( later 5) sites (Finland, France, Italy); pre-production validatedFrance, Italy); pre-production validated

Status:Status:– Ready for integration with SDD: Jul ’06Ready for integration with SDD: Jul ’06– SDD+SSD ready for installation: Sep. ‘06SDD+SSD ready for installation: Sep. ‘06

p-Hybrid

n-Hybrid

Sensor

0

20

40

60

80

J A J O J A J O J A J

lad

der

eq

uiv

alen

t

SSD

modules

EndCaps

ladders

tested sensors

microcables

Ramping of component delivery and assembly


Time Projection Chamber (TPC)Time Projection Chamber (TPC)

GAS VOLUME88 m3

DRIFT GAS90% Ne 10% CO2

Field cage finished

FEE finishedRead out chamber

finished

At present: pre-integration of field

cage into experimentReadout plane segmentation

18 trapezoidal sectors each covering 20 degrees in azimuth

EE

510 cm

EE

88us


TPCMounting the TPC Central ElectrodeWith 10-4 parallelism to readout chambers

Completed Readout chamber installation


Transition Radiation Detector Transition Radiation Detector (TRD) (TRD)

Pad chambers with a total of 1 200 000 channelsPad chambers with a total of 1 200 000 channels

Fully equipped TRD chamber


Time-Of-Flight (TOF)Time-Of-Flight (TOF) Multi-gap RPCMulti-gap RPC

– high performance: 50 ps resolution achieved!high performance: 50 ps resolution achieved!


TOF: performance and TOF: performance and constructionconstruction

DetectorDetector-Strip production: 20/week to -Strip production: 20/week to increase to 40/week with 2increase to 40/week with 2ndnd automated assembly lineautomated assembly line

-Finished : 11/06-Finished : 11/06-Module assembly : start 06/05; -Module assembly : start 06/05; finish : 11/06finish : 11/06

- Supermodules : installation test Supermodules : installation test with mock-up done successfullywith mock-up done successfully

- Start SuperModules installationStart SuperModules installation July/August ‘06July/August ‘06

Testbeam

Cosmic rays

σ(TOF) ~ 60 ps


ITS/TPC/TRD/TOF Pre-ITS/TPC/TRD/TOF Pre-IntegrationIntegration

Pre-Integration of ITS/TPC/TRD/TOF/vacuum chamber

April 2005


Specialized detectors:• HMPID• PHOS


High Momentum Particle Identification High Momentum Particle Identification (HMPID)(HMPID)

Sensitivity of cathodesRequired: >12 clustersMeasured: >18 clusters for

relativistic particles

- Detector production (7 modules) finished-CsI-cathode 35/42 ready and performance better than specified

- Ready for Installation: July ‘06

Cathode uniformity ~ 5 %

x [mm]

Inorm

y [mm]

stdev Ipc( )

mean Ipc( )0.01

mean Ipc( ) 3.71


PbW04: Very dense: X0 < 0.9 cmGood energy resolution (after 6 years R&D):stochastic 2.7% / E1/2

noise 2.5% / Econstant 1.3%

Photon Spectrometer (PHOS)Photon Spectrometer (PHOS)

PbW04 crystal

single arm em calorimetersingle arm em calorimeter photons, photons, -jet tagging-jet tagging

– dense, high granularity dense, high granularity (2x2x18cm(2x2x18cm33) crystals) crystals

novel material: novel material: PbW0PbW044

– ~18 k channels, ~ 8 m~18 k channels, ~ 8 m22

– cooled to -25cooled to -25oo


MUON Spectrometer:• absorbers• tracking stations• trigger chambers• dipole


Muon Magnet :world’s largest warm Muon Magnet :world’s largest warm dipoledipole

Muon Filter


Muon Tracking SystemMuon Tracking System Advanced ‘Pad-chamber’ system withAdvanced ‘Pad-chamber’ system with

– 1.2* 101.2* 106 6 readout channelsreadout channels– Sagitta resolution of < 50 Sagitta resolution of < 50 μμmm for for– Mass resolution of ~ 80 MeV at UpsilonMass resolution of ~ 80 MeV at Upsilon

Production of chambers in Production of chambers in – France, India, Italy, Russia France, India, Italy, Russia – Scheduled to be finished end 2005Scheduled to be finished end 2005


Forward detectors:• PMD• FMD, T0, V0, ZDC

Cosmic rays trigger


Trigger Counters Trigger Counters T0/V0/FMD/AccordeT0/V0/FMD/Accorde

V0: Scintillator + PM

T0: Quartz-C + PM

Accorde: large area Scintillator + PM

trigger on Cosmic rays

FMD: Si -strips


Physics Examples: Physics Examples:

Jet QuenchingJet Quenching

Heavy FlavoursHeavy Flavours


Jet quenchingJet quenching Jets in QCD:Jets in QCD:

- Cascades of consecutive emissions of partons initiated by partons - Cascades of consecutive emissions of partons initiated by partons fromfrom

an initial hard scattering;an initial hard scattering;

- Parton fragmentation - Parton fragmentation showering and hadronization. showering and hadronization.

In-medium effects In-medium effects modifications of the jet structure: modifications of the jet structure:

– Reduction of single inclusive high Reduction of single inclusive high pptt particles: particles:

- Parton specific (stronger for gluons than quarks)- Parton specific (stronger for gluons than quarks)

- Flavour specific (stronger for light quarks)- Flavour specific (stronger for light quarks)

Measure identified hadrons (Measure identified hadrons (, K, p, , K, p, ΛΛ, etc.) + heavy, etc.) + heavy

partons (charm, beauty) at high partons (charm, beauty) at high ppTT

– Change of fragmentation function for hard jets (Change of fragmentation function for hard jets (pptt>>10 GeV/c)>>10 GeV/c)

- Transverse and longitudinal fragmentation functions of jets- Transverse and longitudinal fragmentation functions of jets

- Jet broadening - Jet broadening reduction of jet energy, dijets, reduction of jet energy, dijets, -jet pairs-jet pairs

- Suppression of mini-jets: same-side/away-side correlations- Suppression of mini-jets: same-side/away-side correlations


ExperimentallyExperimentally Highest sensitivity to the medium properties:Highest sensitivity to the medium properties:

- modifications of the reconstructed jets - modifications of the reconstructed jets - partonic energy loss - partonic energy loss decrease particles carrying a high decrease particles carrying a high

fraction of the jet energy and appearance of radiated energy fraction of the jet energy and appearance of radiated energy via an increase of low-energy particles via an increase of low-energy particles

- broadening of the distribution of jet-particle momenta- broadening of the distribution of jet-particle momenta

Measurement of Jet Energy:Measurement of Jet Energy:– In present configuration Alice measures only charged particlesIn present configuration Alice measures only charged particles

( and electromagnetic energy in PHOS)( and electromagnetic energy in PHOS)– The large EM Calorimeter will improve the jet energy resolution, The large EM Calorimeter will improve the jet energy resolution,

increase the selection efficiency and further reduce the bias on increase the selection efficiency and further reduce the bias on the jet fragmentation + jet trigger capabilities needed to the jet fragmentation + jet trigger capabilities needed to increase the statistics at high Eincrease the statistics at high Ett..

Measurement of Jet Structure very important:Measurement of Jet Structure very important:– Requires good momentum analysis from ~ 1 GeV/c to ~ 100 Requires good momentum analysis from ~ 1 GeV/c to ~ 100

GeV/cGeV/c– Alice excels in this domainAlice excels in this domain

pp and pA measurements essential as reference!pp and pA measurements essential as reference!


Energy domains for jet reconstructionEnergy domains for jet reconstruction

2 GeV 20 GeV 100 GeV 200 GeV

Mini-Jets 100/event 1/event 100k/month

• Event structure and properties at p > 2 GeV/c• Correlation studies• Limit is given by underlying event

• Reconstructed Jets• Event-by-event well distinguishable objects

Example :100 GeV jet +underlying event


Reduced cone size...Reduced cone size...

Central PbPb at Central PbPb at √√s=5.5 TeVs=5.5 TeV– ddNNchch/d/dyy = 2000-8000 = 2000-8000

– ddEETT/d/d ~ 1.5-6 TeV ~ 1.5-6 TeV

– Energy in Energy in R R < 0.7: 0.4 -1.5 TeV< 0.7: 0.4 -1.5 TeV

ProblemsProblems– Identification...Identification...– Energy resolution: Energy resolution:

background fluctuations background fluctuations comparable to jet energycomparable to jet energy

use smaller cone size, R ~ use smaller cone size, R ~ 0.30.3

size) cone ( )()( 22 R

e.g.: for 100 GeV jete.g.: for 100 GeV jet

Large underlaying hadron background reduced cone size R


Jet quenching?Jet quenching? Excellent jet reconstruction… Excellent jet reconstruction…

but challenging to measure but challenging to measure global medium modification global medium modification … …

EEtt=100 GeV (reduced average jet =100 GeV (reduced average jet energy fraction inside R):energy fraction inside R):– Radiated energy ~20% Radiated energy ~20% – R=0.3 : dE/E=3%R=0.3 : dE/E=3%

-Most of radiated energy stays within cone

-Jet quenching rather means a medium-induced redistribution of the jet energy inside the jet cone

Jet shape: average fraction of energy in a sub-cone of radius R


Low-pLow-pT T tracking essential...tracking essential...Simple quenching model:The energy loss of a 100 GeV jet is simulated by reducing the energy of the jet by 20% and replacing the missing energy by:

1 x 20 GeV gluon

2 x 10 GeV gluons

4 x 5 GeV gluons

(Jets simulated with Pythia)

Summary:

ALICE combines low-pt tracking and PID study of the jet-structure over a wide range of momenta and particle species.

Jet reconstruction restricted to relatively high-energy jets(Et>30-40 GeV) while leading particle correlation studies play an importantrole in the low-Et region.


Heavy FlavoursHeavy Flavours LHC is the first machine where heavy quarks will be LHC is the first machine where heavy quarks will be

produced abundantly in heavy-ion collisions.produced abundantly in heavy-ion collisions.

Heavy flavour production in pp and AA collisions to pHeavy flavour production in pp and AA collisions to ptt ≈0:≈0:

- open charm and open beauty:- open charm and open beauty:- mechanism of heavy-quark production, propagation and - mechanism of heavy-quark production, propagation and hadronisation (in-medium quenching compared to hadronisation (in-medium quenching compared to

massless partons) massless partons) - cross sections as a reference for quarkonia production- cross sections as a reference for quarkonia production excellent impact parameter resolution (secondary vertex) excellent impact parameter resolution (secondary vertex)

and and PID capability PID capability wide p wide ptt range range

- quarkonia:- quarkonia:

- yields and p- yields and ptt spectra of J/ spectra of J/, , ’, ’, , , ’ and ’ and ’:’: ee++ee- - in central region and in central region and ++-- in forward region in forward region


Heavy flavour energy loss?Heavy flavour energy loss?

Energy loss for heavy flavours is expected to be reduced Energy loss for heavy flavours is expected to be reduced harder pharder ptt spectra for heavy- wrt light-flavour mesons: spectra for heavy- wrt light-flavour mesons:

i)i) Casimir factorCasimir factorlight hadrons originate predominantly from gluon jets, heavy light hadrons originate predominantly from gluon jets, heavy flavoured hadrons originate from heavy quark jets flavoured hadrons originate from heavy quark jets

CCRR is 4/3 for quarks, 3 for gluons is 4/3 for quarks, 3 for gluons ii)ii) dead-cone effectdead-cone effect

gluon radiation expected to be suppressed for gluon radiation expected to be suppressed for < M < MQQ/E/EQQ

(heavy quarks with momenta < 20-30 GeV/c (heavy quarks with momenta < 20-30 GeV/c v << c) v << c)[Dokshitzer & Karzeev,[Dokshitzer & Karzeev, Phys. Lett. Phys. Lett. B519B519 (2001) 199] [Armesto et al., Phys. Rev. D69 (2004) (2001) 199] [Armesto et al., Phys. Rev. D69 (2004)

114003]114003]

2 ˆ LqCE Rs

Casimir coupling factortransport coefficient of the medium( gluon density probe the medium)

average energy lossdistance travelled in the medium

R.Baier et al., Nucl. Phys. B483 (1997) 291 (“BDMPS”)


RRAAAA(D) in ALICE(D) in ALICE

Low pT (< 6–7 GeV/c)Nuclear shadowing

‘High’ pT (6–15 GeV/c)Energy loss can be studied (it is the only expected effect)

The dead cone effect can be studied in the pThe dead cone effect can be studied in the ptt--dependence of the nuclear modification factor Rdependence of the nuclear modification factor RAAAA

good sensitivity for measurement of c quenchinggood sensitivity for measurement of c quenching

TBD

pp

TBD

AA

collT

BDAA dpdN

dpdN

NpR

/

/1)(

,

,,

Nuclear modification factor:

production yield in AA collisionsnormalized to elementary ppcollisions, scaled with thenumber of binary collisions


Weak decay with mean proper length cWeak decay with mean proper length c = 124 = 124 μμmm Track Impact Parameter (distance of closestTrack Impact Parameter (distance of closest approach of a track to the primary vertex) of theapproach of a track to the primary vertex) of the decay products ddecay products d00 ~ 100 ~ 100 μμmm

STRATEGY: invariant mass analysis of fully-reconstructed topologies STRATEGY: invariant mass analysis of fully-reconstructed topologies originating from (displaced) secondary verticesoriginating from (displaced) secondary vertices

- Measurement of Impact Parameters- Measurement of Impact Parameters- Measurement of Momenta- Measurement of Momenta- Particle identification to tag the two decay products- Particle identification to tag the two decay products

Detection strategy for DDetection strategy for D00 K K--++

expected dexpected d00 resolution ( resolution ())


DD00 K K--++

expected ALICE expected ALICE performanceperformance – S/B ≈ 10 %S/B ≈ 10 %– S/S/(S+B) ≈ 40 (S+B) ≈ 40

(1 month Pb-Pb (1 month Pb-Pb running)running)

statistical.

systematic.

ppTT - differential - differential similar performance in ppsimilar performance in pp

(wider primary vertex spread)(wider primary vertex spread)


Proposed ALICE EMCALProposed ALICE EMCAL

• Rails already installed • Support structure funded by DoE, to be installed this summer• 10 +1/2+1/2 Supermodules (SM)• 1 SM = 24x12 modules• 1 module = 4 channels : • 1.2 x 104 total channels (granularity)

To improve the capabilities in triggering and measurement of high energy jets

EM Sampling Calorimeter (STAR Design)EM Sampling Calorimeter (STAR Design)

Pb-scintillator linear response Pb-scintillator linear response

-0.7 < -0.7 < < 0.7 < 0.7

/3 < /3 < < < (opposite to PHOS)(opposite to PHOS)

Energy resolution ~15%/√EEnergy resolution ~15%/√E


EMCALEMCAL

• Single detector : 6x6x25 cm3 shashlik 1.44mm Pb/1.76mm scintillator sampling • 77 layers = 20 Xo • WLS fiber+APD readout• Front End Electronics mainly developed for TPC and PHOS• First SM to be ready for 2008 run • Full Calorimeter to be completed for 2010 run

EMCAL Project: Italy (LNF, Ct) + France + US


ConclusionsConclusions LHCLHC

– the next jump in heavy-ion physicsthe next jump in heavy-ion physics““it is dangerous to make predictions, especially about the it is dangerous to make predictions, especially about the future”future”

– significant extension of reach at both soft and hard frontierssignificant extension of reach at both soft and hard frontiers

ALICEALICE– dedicated heavy-ion experimentdedicated heavy-ion experiment– address most relevant observables, from very soft to very hard address most relevant observables, from very soft to very hard – novel technologies!novel technologies!

production well under wayproduction well under wayBusy months ahead working detector well on track for the start-up of LHC (summer 2007)

– Study collisions of lower-mass ions (varying energy density) Study collisions of lower-mass ions (varying energy density) and protons (pp and pA) as referenceand protons (pp and pA) as reference

– pp data will also allow for a number of genuine pp physics pp data will also allow for a number of genuine pp physics studiesstudies

we are looking forward towards exciting times!we are looking forward towards exciting times!

the alice experiment at lhc: detector & physics

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