French-Spanish collaboration within the ALICE experiment

Ginés Martínez GarcíaSubatech, Nantes, France

Néstor ArmestoUniversidade de Santiago de Compostela, Spain

Preface• Experiment at the LHC;• Spanish teams have joined ALICE

recently:– Collaboration meeting in Bologna in 2006;

• Many topics of common interest have been identified;

• Spanish contribution reminds modest: 1 permanent physicist at CIEMAT and 3 physicists of the theoretical group from Santiago de Compostela.

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Phases of matterPhases of matter

Goal of the HI program Understanding of hadron mass in the

Standard Model - confinement - through the creation of extended regions with large energy densities (parametric estimates: ~4-40 GeV/fm3 for V~1000 fm3).

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Complementary to other LHC high-energy studies - potential for discovering new phenomena at high energy density - using the same accelerator and detectors.

Complementary to other LHC high-energy studies - potential for discovering new phenomena at high energy density - using the same accelerator and detectors.

LHC running conditions @ P2

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System sNN1/2(TeV) L0(cm-2s-1) <L>/L0 Run time (s yr-1) (b) Statistics

pp 14 <1031 107 0.07 7X1012

PbPb 5.5 1027 ~50% 106 7.7 4X109

Nominal conditionsNominal conditions

• Other Heavy-Ion like systems: pp 5.5 TeV, pPb, lighter ions (O, Ar, Kr, Sn).

QGP

A Large heavy Ion Collider Experiment

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LoI LHCC-93-16 (March 1st 1993), TP LHCC 95-71, TDRs (1997-2008), PPRs JoP G30 11 (2004) & JoP G32 10 (2006), 1st Physics publication expected in 2009.LoI LHCC-93-16 (March 1st 1993), TP LHCC 95-71, TDRs (1997-2008), PPRs JoP G30 11 (2004) & JoP G32 10 (2006), 1st Physics publication expected in 2009.

y

z

x

Side A

Side C

Inside LHC

ALICE collaboration

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• ~ 1000 members (63% from CERN member states);

• 30 countries;• 100 laboratories;• France M&O-2008

member list around 11%;

• Spain/Cuba M&O-2008 member list around 1%.

Topics of common interest

• Hard probes:– Quarkonia and open heavy flavours;

– High-pT particles and jets;

• Alice computing grid:– Tiers-2 developments;

• Future ALICE detector upgrades.

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Quarkonia Physics

• Color screening of the heavy quark potential;• New energy domain at LHC: large number of

HQ pairs;• Measuring upsilon resonances.

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Quarkonia in ALICE

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• Heavy quarkonia states, heavy quark production in the muon & electron channel;

• Charmonia from pT=0 GeV/c;

• Separation of Upsilon states;• Acceptance ||<0.9 & -2.5<<-

4.0;• Potential complications:

• Cold nuclear matter effects;• Feed-down from higher

resonances;• B-hadron decays.

ALICE muon Spectrometer ALICE muon Spectrometer

Measurement of c production in proton-proton collisions via

its radiative decay +J/;Item developed by the

CIEMAT group within the PWG3 group.

Measurement of c production in proton-proton collisions via

its radiative decay +J/;Item developed by the

CIEMAT group within the PWG3 group.

c Analysisc (M=3.5GeV)

J/(M=3.1 GeV) + l+

+l-• Photon detected via

external conversion in the ALICE TPC:

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P. Ladrón de Guevara et al., Hard Probes 2008arXiv:08:11.1592v1 [hep-ex]

P. Ladrón de Guevara et al., Hard Probes 2008arXiv:08:11.1592v1 [hep-ex]

Work in progress: Trigger efficiency, extrapolation to AA.Collaboration with A. Marin, GSI

ee

l

lc

Energy loss of Heavy Quarks• Suppression of high-pT

particles has been one of the golden observations at RHIC;

• Interpretation of these data based on the energy loss of quarks and gluons crossing the QGP (in which Santiago is a leading international group);

• At LHC energies, muons will provide a non-ambiguous observation of beauty quark energy loss.

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N. Armesto et al., PRD 71, 054027 (2005).N. Armesto et al., PRD 71, 054027 (2005).

Muon distribution at the LHC

• W as a medium blind reference of the beauty Eloss in QGP.

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Decay Collision Statistics

Muonic p-p, 14 TeV 86 000

Muonic Pb-Pb, 5.5 TeV, MB 14 000

Muonic Pb-Pb, 5.5 TeV, 0-10CC

6000

Z. Conesa del Valle et al. PLB663, 202 (2008)Z. Conesa del Valle et al. PLB663, 202 (2008)

ALICE Computing Grid• Standard

computing Model: – Tier0 (CERN), Tier1,

Tier2;

• Lower event rate, but larger event size;

• Requirements:– CPU ~ 80 MSi2K;– DISK ~ 30 PB;– MSS ~ 40 PB;

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• France: 1 Tier1 and 6 Tier2;

• Spain: 1 Tier2

ALICE Tier2• Averaged ALICE Tier2:

– 1.7 MSI2K CPU and 270 TB disk;

• Spain (Tier2 Madrid/Trujillo):– 0.18 MSI2K CPU and 35 TB disk and 60 TB MSS.

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Potential collaboration: Development of one new Tier2; Analysis facilities.

Potential collaboration: Development of one new Tier2; Analysis facilities.

Other collaborations • Organization of Conferences:

– Contribution of IN2P3 to Hard Probes 2008 and Hot Quarks 2008;

• European networks of I3HP2 7FP:– JetCal (Jet Physics in HIC);– ReteQuarkonii (Quarkonia Physics in HIC);

• Other French-Spanish collaborations:– Ecole Polytechnique and LPT Orsay about cold

nuclear matter effects;– LPTHE Jussieu about jets in heavy ion

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Future plans• Reinforcement and extension of the

collaborations; training within EU networks;• Extension of studies of heavy quark energy

loss to charm;• Studies of jet reconstruction with the TPC+

EMCAL in the heavy ion environment;• Enlargement of the contribution to the

ALICE-GRID; • Future detector upgrades.

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