experiment cbm – research program

Experiment CBM – research program

Paweł StaszelJagiellonian University

Physics motivation Detector concept Feasibility study Status

Paweł Staszel V Polish Workshop on Relativistic Heavy-Ion Collisions, Kielce 7.12.2008 2

Diagram fazowy QCD


QCD Phase Diagram scan with A+Acollisions

V.Toneev et al., nucl-th/0309008

3 component hydrodynamics + hadron gas EOS:

Critical Point reached at trajectory for ~30 AGeV (√s

NN=7.74)

Phase Boundary reached already at ~10 AGeV (√s

NN=4.72)


How to explore interesting regions of the QCD Phase Diagram

Lattice QCD calculations:Fedor & Katz,Ejiri et al.

Freeze-out phase can be studied by measurement of „soft” hadrons production (bulk observables)

Information about earlier phases is carried by rare probes:

• High pT particles

• Particles decaying in to leptons• Particles build up of heavy quarks (J/ψ, D, Λc ....)

and by collective motion (flow) of the created soft medium. (e .g. v

2 is

sensitive to the quanta interaction just after the medium formation)

large advantage from simultaneous flow measurement of “ordinary” hadrons and rare probes


Experymental arguments for Phase Transition at low SPS energy

NA49 (QM 2004)

None monotonic behaviour of K+/+ ratio

Effective temperature shows plateau in the range of SPS energy


Hadrons in dense medium (->e+e-)

Top SPS: excess of e+e- pairs around 0.5 GeV (by factor of ~2.8)40AGeV: the excess rised up to ~4 → strong dependency on

B

Rapp-Wambach – in-medium modification

Rapp: “dropping mass” according to Brown-Rho scaling scenario

Thermal model


Hadrons in dense medium (->+-)

NA60, Nucl. Phys. A 774 (2006) 67

broadening of spectral function (Rapp-Wambach)

contradiction with mass drop scenario (Brown-Rho scaling)

excess by factor of 4 over the “cocktail” with 25% systematic uncertainty !


Open Charm in dense medium

Mishra et al, nucl-th/0308082

Reduction in the effective mass of D-meson can open D-Dbar decay channel for charmonium states → possible scenario for the J/Ψ suppression, CBM=> simultaneous measurement of J/Ψ and D-mesons


J/Ψ suppression

Anomalous J/ψ suppresion (AS) on SPS, L – effective path in medium

NA50, QM 2005

NA60 evidenced same effect in In+In

Better scaling is obtained in Npart; onset already at Npart~90,At lower energies (larger μ

B)

one can expect onset of AS for more central collisions →

dependency on energy density and μB

Important measurement of open charm to verify other scenarios


Elliptic flow

KET = mT-m

• all particles flow (even these with charm!)

• scaling if taking the underlying number of quarks into account!

→like (all!) quarks flow and combine to hadrons at a later stage (hadronisation)

• data can only be explained assuming a large, early built up pressure in a nearly ideal liquid (low viscosity!)

baryons n=3mesons n=2

[PHENIX, PRL.98:162301,2007]


Elliptic flow at SPS

data at top SPS support hypothesis of early development of collectivity• influence of hadronic rescattering phase, resonance decay? • lack of complete thermalization, viscosity effect?• larger pt-range needed

Pb+Pb collisions, √sNN = 17.3 GeV

[NA49, G. Stefanek, PoS CPOD2006:030,2006]


Event-by-event fluctuations

[NA49 collaboration, arXiv:0810.5580v2 [nucl-ex]]

• observation might become enormously difficult

• correlation length of sigma field, may become rather small for a finite lifetime of the fireball

• large acceptance needed!

2

2

pt

pt

pt zN

Z=Φ

N

=ittipt

ttpt

pp=Z

pp=z

1

[Stephanov, Rajagopal, Shuryak, PRD60, 114028 (1999)]

1st try to identify 1st order phase transition line

fluctuations, correlations with large acceptance and particle identification


Dynamical Fluctuations (by D. Kersan)

Measure the particle yields ratio in an event :

K/

Relative width of distribution : = RMS / MEAN

data2 = fin

2 + exp2 + dyn

2

background

Event mixing: no two tracks coming from one real event mixed

dyn2 = data

2 mixed2


Dynamical Fluctuations in UrQMD

4 RECO+ PID


Toy ModelToy Model features:1. Independent particle production with yields and kinematics from UrQMD2. Extra kaon multiplicity fluctuation3. Resonance decays


Resonances in Toy Model – K*

K*(892)0 K

<K> = 41<> = 363

Independentlyproduced:


Resonances in Toy Model –

K+K

K0LK0

S

0 00

+

<K> = 41<> = 363

Independentlyproduced:

analytical formula


Conclusion (fluctuation feasibility study)

Hadron ID and event-by-event fluctuations of the kaon to pion ratio were studied with full event reconstruction in CBM

Kaons can be identified up to p = 3.5 GeV/cThe current setup is sensitive to event-by-

event fluctuations above 1 %Resonance decays influence the fluctuation

measure; the effect obtained in a toy model is in agreement with analytical predictions


CBM: Physics topics and Observables

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) charmonium suppression, sequential for J/ψ and ψ' ? corelated with open charm ?

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,...)

predictions? clear signatures?→ prepare to measure "everything": bulk particles and rare probes ⇒ probing medium with known overall characteristics→ systematic studies! (pp, pA, AA, energy)


Heavy Ion Experiments (selection)

time (advance in technology)

LHCLHC

RHICRHIC

SPSSPS

SIS300SIS300

SIS18SIS18BevalacBevalac

SIS 100SIS 100AGSAGS

Inner Tracker

HPID

TPC

upgrade

CCBBMMGAP


CBM Detector (->e+e-)

TRDs(4,6,8 m)

STS ( 5 – 100 cm)


CBM Detector (->+-)

beam

ABSORBER(1,5 m)

TRDs(4,6,8 m)

TOF(10 m)

ECAL(12 m)

STS ( 5 – 100 cm)

magnet


Silicon Tracking Station – heart of CBM

Challenge: high track density: 600 charged particles in 25o @10MHz

Tasks:• track reconstruction: 0.1 GeV/c < p 10-12 GeV/c p/p ~ 1% (p=1 GeV/c)• primary and secondary vertex reconstruction (resolution 50 m)

V0 track pattern recognition

c = 312 m

radiation hard and fast silicon pixel and strip detectors

self triggered FEE

high speed DAQ and trigger

online track reconstruction!


Simulation: rare probes

D0

c

J/ J/

di-electrons di-muons

' '


Simulation: bulk particles and hyperons

0

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y0 0.5 1 1.5 2 2.5 3 3.5 4

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$V/c

]T

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$V/c

]T

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$V/c

]T

p

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1

1.2

1.4

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1.8

2

incl. TOF

10 35AGeV

Λ Ξ Ω


Hiperons: PID from decay topology in STS


Status

CBM Collaboration undergoes (phase) transition

simulation → prototyping


Double and triple GEM detectors2 Double-sided silicon microstrip detectors Radiation tolerance studies for readout electronics Full readout and analysis

chain:

Front-end board with self-triggering n-XYTER chip Readout controller

Data Acquisition System

online

offline

Go4

AnalysisDetector

signals

Successful test of CBM prototype detector systems with free-streaming read-out electronics using proton beams at GSI, September 28-30, 2008

GSI and AGH Krakow VECC Kolkata KIP Heidelberg


CBM hardware R&D

RICH mirror

n-XYTER FEB

Silicon microstrip detector

MVD: Cryogenic operation in vacuum RPC R&D

Forward Calorimeter

GEM

dipole magnet


CBM CollaborationChina:Tsinghua Univ., BeijingCCNU WuhanUSTC Hefei

Croatia:

University of SplitRBI, Zagreb

Portugal: LIP Coimbra

Romania: NIPNE BucharestBucharest University

Poland:Krakow Univ.Warsaw Univ.Silesia Univ. KatowiceKraków AGH(Inst. Nucl. Phys. Krakow)

LIT, JINR DubnaMEPHI MoscowObninsk State Univ.PNPI GatchinaSINP, Moscow State Univ. St. Petersburg Polytec. U.

Ukraine: INR, KievShevchenko Univ. , Kiev

Univ. MannheimUniv. MünsterFZ RossendorfGSI Darmstadt

Czech Republic:CAS, RezTechn. Univ. Prague

France: IPHC StrasbourgGermany: Univ. Heidelberg, Phys. Inst.Univ. HD, Kirchhoff Inst. Univ. Frankfurt

Hungaria:KFKI BudapestEötvös Univ. BudapestIndia:Aligarh Muslim Univ., AligarhIOP BhubaneswarPanjab Univ., ChandigarhGauhati Univ., Guwahati Univ. Rajasthan, JaipurUniv. Jammu, JammuIIT KharagpurSAHA KolkataUniv Calcutta, KolkataVECC Kolkata

Univ. Kashmir, SrinagarBanaras Hindu Univ., Varanasi

Korea:Korea Univ. SeoulPusan National Univ.Norway:Univ. Bergen

Kurchatov Inst. MoscowLHE, JINR DubnaLPP, JINR DubnaCyprus:

Nikosia Univ.

55 institutions, > 400 members

Dubna, Oct 2008

Russia:IHEP ProtvinoINR TroitzkITEP MoscowKRI, St. Petersburg


Mapping the QCD phase diagram with heavy-ion collisions

net baryon density: B 4 ( mT/2h2c2)3/2 x

[exp((B-m)/T) - exp((-B-m)/T)] baryons - antibaryons

Lattice QCD calculations:Fedor & Katz,Ejiri et al.

SIS300

experiment cbm – research program

Documents

heavy quarks j

dense medium e e

sps data

quarks flow

simultaneous measurement

effective mass of d

excess of e e pairs

low sps energy