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Physics of High Baryon Densities - The CBM experiment at FAIR

Subhasis Chattopadhyay Variable Energy Cyclotron Centre, Kolkata

for the CBM collaboration

Outline:Outline:

CBM physics CBM physics CBM setup CBM setup Feasibility studiesFeasibility studies Detector R&D Detector R&D

CBM

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RHIC result: new state of matter = perfect liquid? Tf = 160 – 165 MeV

L-QCD Predictions: TC = 151 ± 7 ± 4 MeV ( μB=0 ) (Z. Fodor, arXiv:0712.2930 hep-lat) TC = 192 ± 7 ± 4 MeV ( μB=0 ) (F. Karsch, arXiv:0711.0661 hep-lat) crossover transition at μB=0 (Z. Fodor, arXiv:0712.2930 hep-lat) 1. order phase transition with critical endpoint at μB > 0

High-energy heavy-ion collision experiments:

RHIC, LHC: cross over transition, QGP at high T and low ρLow-energy RHIC: search for QCD-CP with bulk observables NA61@SPS: search for QCD-CP with bulk observables CBM@FAIR: scan of the phase diagram with bulk and rare observables

Exploring the QCD Phase diagram

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What is the equation-of-state of strongly interacting matter? (core collapse supernovae, neutron stars, early universe)

What is the structure of strongly interacting matter as a function of T and ρB ?

(hot and dense hadronic medium, deconfined phase, phase transitions ?)

What are the in-medium properties of hadrons as a function of T and ρB ? (restoration of chiral symmetry ?)

Questions of QCD

After RHIC & LHC we need measurements at large baryon density

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Onset of chiral symmetry restoration at high B

in-medium modifications of hadrons (,, e+e-(μ+μ-), D)

Deconfinement phase transition at high B

excitation function and flow of strangeness (K, , , , ) excitation function and flow of charm (J/ψ, ψ', D0, D, c)

The equation-of-state at high B

collective flow of hadrons particle production at threshold energies (open charm?)

QCD critical endpoint excitation function of event-by-event fluctuations (K/π,...)

CBM: detailed measurement over precise energy bins (pp, pA,

AA) FAIR beam energy range 2-45 AGeV (protons 90 GeV)

What do we need to measure?

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Net-baryon densities in central Au+Au collisions at FAIR:consistent picture from transport models

Compilation by J. Randrup, CBM Physics Book, in preparationsee also I.C. Arsene et al., Phys. Rev. C 75 (2007) 034902

At FAIR energy: large baryon density will be achieved over long time

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Elliptic flow at FAIR

AMPT calculations: C.M. Ko at CPOD 2007

Measure flow for all particles over CBM energy range

DJ/

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Quarkonium dissociation temperatures: (Digal, Karsch, Satz)

Measure excitation functions of J/ψ and ψ' in p+p, p+A and A+A collisions !

rescaled to 158 GeV

Probing the quark-pluon plasma with charmonium

J/ψ ψ'

sequential dissociation?

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L. Grandchamp, R. Rapp and G. E. Brown, J.Phys. G30 (2004) S1355

In-medium modifications

Mass modifications of D mesons and charmed hyperons affect the ratios ψ'/ψ and charmonium to open charm

A. Andronic, P. Braun-Munzinger, K. Redlich, J. Stachel, arXiv:0708.1488

D mesons

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hep-ph/0604269

Hadronic properties are expected to be affected by the enormous baryon densities

→ -meson is expected to melt at high baryon densities

In-medium modifications

no ρ,ω,φ → e+e- (μ+μ-) data between 2 and 40 AGeV no J/ψ, ψ' → e+e- (μ+μ-) data below 160 AGeV

Data: CERESCalculations: R. Rapp

Data: In+In 158 AGeV, NA60Calculations: H.v. Hees, R. Rapp

mesons

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Measurements and Challenges

11SIS100/300

Multiplicity in central Au+Au collisionsW. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745

Rare particles with high statisticsHigh beam intensityInteraction rate: 10 MHzFast detectors/DAQ

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Dipolemagnet

The Compressed Baryonic Matter Experiment

Ring ImagingCherenkovDetector

Transition Radiation Detectors Resistive

Plate Chambers(TOF)

ECAL

SiliconTrackingStation

Tracking Detector

Muondetection System

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Full event reconstruction: • 2 low-mass pixel, 6 micro-strip detectors• proton identification via TOF

Benchmark for Vertex-Tracker performance: D mesons and ΛC from Au+Au central collisions at 25

AGeVD and ΛC multiplicity from HSDHadronic background from UrQMD

τ = 123 μm/cD0

K-

π+

D0

ΛC → π+K-p τ = 60 μm/c

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Electron pairs in CBM

J/ψ → e+e-

ρ, ω, φ → e+e-

Central Au+Au collisions at 25 AGeV

particle S/B ε (%)

ω 0.4 6.6

φ 0.32 9.4

ρ 0.008 4.7

J/ψ 13 14

Ψ' 0.3 19

25 μm target

Talk: C. Hoehne, parallel session XXIII

Posters: T. Galatyuk K. Antipin

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Central Au+Au collisions at 25 AGeV

ρ, ω, φ → μ+μ-J/ψ, ψ' → μ+μ-

particle S/B ε (%) σ (MeV)

ω 0.11 4 10

φ 0.06 7 12

ρ 0.002 3

J/ψ 18 13 21

Ψ' 1 16 27

Muon pairs in CBM

Talk: C. Hoehne, parallel session XXIII Poster: A. Kiseleva, P. Bhaduri

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Annual yields at RHIC II & LHCfrom Tony Frawley RHIC Users mtg.

at LHC: (10-50) x ~10% of L 25% running time

10 weeks CBMAu+Au 25 AGeV

B. Jacak QM2006

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R&D on the Silicon Tracking System

R&D effort:

micro-strip detector modules low-mass mechanics sectors of different strip lengths r/o electronics outside aperture 10 MHz full-frame readout

Design of low-mass detector modules

Micro-strip detector prototype CBM01, Cooperation GSI-CIS.

R&D on ultra-low-mass readout cables. Cooperation with SESRTIIE Kharkov.

1025 lines, 55 cm long, 100 µm pitch1025 lines, 55 cm long, 100 µm pitch

Material: 14 µm Al on 10 µm KaptonMaterial: 14 µm Al on 10 µm Kapton

sensor

cable

FEE

First mechanical module prototype, KINR Kiev.

Front-end electronics prototyping with n-XYTER chip, GSI-DETNI.

System design

Poster: J. Heuser

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Fe Fe Fe Fe Fe

20 20 2

0 30

35 cm

102.5 cm0 cm5 cm

260cm

Chambers: high resolution gas

detectors (major Indian

participation)

Challenges: High Rate High density Large background

Muon detection systemMuon detection system

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GEM (fast high resolution detector) under test at VECC-Kolkata

Resistive chain biasing

6 mm holes in the plexiglasstop cover for Source.

Gas Inlet

source

GEM assembly housed in ~60 cm x ~30 cm box

Gas: Ar/CO2-70/30Source: Ru106(ß)

mesh – a 5-10 micronthick nichrome wire

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Self-triggered fast readout chipfor double-sided Silicon Strip detectors and GEM detectors (128 channels, 32 MHz) under test in the GSI Detlab.

Poster: W. Mueller

High speed DAQOnline Event selection

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Summary and Conclusions

• Exploration of QCD phase diagram at high baryon densities • Precision measurement of excitation functions including rare probes in pp, pA and AA

• CBM: Next generation heavy ion experiment at reaction rates up to 10 MHz

• Fast detectors, High speed DAQ, online event selection

• Simulation shows the feasibility of rare probe measurements

• Detector R&D in progress

CBM

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CBM Collaboration : 51 institutions, ~ 400 membersCroatia: RBI, ZagrebSplit Univ.China:CCNU WuhanUSTC HefeiCyprus: Nikosia Univ. Czech Republic:CAS, RezTechn. Univ. PragueFrance: IPHC StrasbourgHungaria:KFKI BudapestBudapest Univ.

   

Romania: NIPNE BucharestRussia:IHEP ProtvinoINR TroitzkITEP MoscowKRI, St. PetersburgKurchatov Inst., MoscowLHE, JINR DubnaLPP, JINR DubnaLIT, JINR DubnaMEPHI MoscowObninsk State Univ.PNPI GatchinaSINP MSU, Moscow St. Petersburg P. Univ.Ukraine: Shevshenko Univ. , Kiev

India:Aligarh Muslim Univ.Panjab Univ. Rajasthan Univ.Univ. of Jammu Univ. of KashmirUniv. of CalcuttaB.H. Univ. VaranasiVECC KolkataSAHA KolkataIOP BhubaneswarIlT KharagpurKorea:Korea Univ. SeoulPusan National Univ.Norway:Univ. Bergen

Supported by EU FP6

Germany: Univ. Heidelberg, P.I.Univ. Heidelberg, KIP Univ. FrankfurtUniv. Mannheim Univ. MünsterFZ DresdenGSI DarmstadtPoland:Jag. Univ. KrakowWarsaw Univ.Silesia Univ. KatowiceAGH KrakowPortugal: LIP Coimbra

CBM Collaboration Meeting in Strasbourg Sept. 2006

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Backup slides

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Phase space coverage-meson

• 25 AGeV beam energy: midrapidity = 2

• electrons: full coverage

• muons: acceptance forward shifted, weak for low-pt

muonselectrons

25 AGeVcentral AuAu