Experiment at FAIR

Compressed Baryonic Matter

Exploring Phase Diagram of strongly Interacting Matter using

High Energy Heavy Ion Collisions

Subhasis Chattopadhyay, VECC

•Why high energy heavy ion experiment at FAIR important?

•CBM experiment

•Why should we participate?

•How should we participate?

•Travel so far..

•RoadMap

OUTLINEOUTLINE

States of strongly interacting matter

baryons hadrons partons

Compression + heating = quark-gluon matter (pion production)

Neutron stars Early universe

Phase Diagram from cartoon to precise

Tool: High energy heavy ion collisions, generate density/temparature

Quark Gluon Plasma(the definition)

When the energy density exceeds some typical hadronic value (~1 GeV/fm^3), matter no longer consists of separate hadrons (protons, neutrons etc.), but as their fundamental constituents, quarks and gluons. Because of the apparent analogy with similar phenomena in atomic physics we may call this phase of matter the QCD (or quark-gluon) plasma. : PHENIX white paper

QGP=a (locally) thermally equilibrated state of matter in which quarks and gluons are deconfined from hadrons, so that color degrees of freedom become manifest over nuclear, rather than merely nucleonic, volumes. Not required: Non interacting quarks and gluons : Chiral symmetry restored : 1st or 2nd order phase transition : STAR white paper

timelineCourtesy of S. Bass

correlations:(1) thermalization?(2) is there conical

flow?

elliptic flow:(1) does hydro work?(2) what EOS?

hadronshadronic scatterings

freeze-out

1 2 3Initial condition: CGC

high-Q2 interactions

medium formation

hot, dense medium

expansion

hadronization

ratios, spectra:freeze-out propertiesfluctuations, etc.

SPS to RHIC : journey continuing…Observations:

SPS• Matter is different than ordinary nuclear matter, needs different treatment..• Some smoking gun signatures (J/Psi suppression) exist• Not all signatures gave smoke.RHIC:

•The matter is extremely dense and it thermalizes very rapidly.• Estimates of the energy density (10-15 GeV/fm^3) well in excess of the density needed for a QGP predicted by LQCD• Matter seems to be strongly interacting with no viscosityButNeed to have (unequivocal) evidence that

•matter is deconfined•Order of Phase Transition (Cross-over)?

Our journey: SPS@CERN

2cm x 2cm scintillator 8000 cells WA93(data taken: 1991)

52000 cells, WA98(Data taken: 1993-1996)

STAR experiment at RHIC, BNL

Our understanding so farQuick glimpses

Leading hadron suppression

-

Wang and Gyulassy: E softening of fragmentation suppression of leading hadron yield

ddpdT

ddpNdpR

TNN

AA

TAA

TAA /

/)(

2

2

Ivan Vitev, QM02

Inclusive yield relative to binary-scaled p+p

Suppression of the inclusive yield in central Au+Au is a final-state effect

• d+Au : enhancement Au+Au: strong suppression

• pT=4 GeV/c: cent/minbias = 1.110.03 central collisions enhanced wrt minbias

ddpdT

ddpdNR

Tpp

AB

TAB

AB /

/

Azimuthal distributions

pedestal and flow subtracted

Near-side: p+p, d+Au, Au+Au similarBack-to-back: Au+Au strongly suppressed relative to p+p and d+Au

Suppression of the back-to-back correlation in central Au+Au is a final-

state effect

Suppression of away-side jet consistent with strong absorption in bulk, emission dominantly from surface

?

15

A related question: the initial condition

• Large nucleus (A) at low momentum fraction x gluon distribution saturates ~ 1/s(QS

2) with QS2 ~ A1/3

• A collision puts these gluons ‘on-shell’ ~ A xg(x,Q2) / R2

• Parton-hadron maps gluons directly to charged hadrons

• Parton dynamics in a dense system of gluons differs from pQCD

• Saturated gluon density ( CGC ) effective field theory of dense gluon systems provides an appropriate description of the initial condition

D. Kharzeev, E. Levin and L. McLerran, Phys. Lett. B 561 (2003) 93

Highlight of the first paper from STAR PMD

First time in Heavy-Ion collisions we showed that photons and pions follow energy independent limiting fragmentation.

We have resolved the contradictory results (from two contemporary experiments at RHIC) on the impact parameter dependence of limiting fragmentation of charged particles.

What have we learned (so far)?

+The matter is extremely dense and it thermalizes very rapidly. First order estimates of the energy density all well in excess of the density needed for a QGP predicted by LQCD (~ 10-15 GeV/fm3).

But– Need to have (unequivocal) evidence that

• the matter is deconfined• Order of Phase Transition (Cross-over)?• sQGP (strongly interacting) with no viscosity

What have we learned (so far)?• Demand an explanation beyond a purely hadronic scenario:

– The hydro-models require early thermalization (therm< 1fm/c) and high initial energy density > 10 GeV/fm3

– Implies the matter is well described as ideal relativistic fluid

– Initial gluon density dng/dy~1000 and initial energy density e~15 GeV/fm3 are obtained model of jet quenching.

• Estimates of energy density are well in excess of ~1 GeV/fm3 obtained in lattice QCD as the energy density needed to form a deconfined phase.

Meanwhile, SPS people have started looking at Their data again…

Interestingly, many RHIC observations are reproduced and then new ones..

Make more precision measurement at SPS energies. Only Hadronic observables..

The Kink

Van-Hove

Fluctuation

one more speculation ....

coexistence phase

hadronsQGP

critical point

ENERGY SCAN….ENERGY SCAN….

In fact, energy scan is done....RHIC

What has not been done:

Looking in extreme detail at lower energies.Effort was to get hot QGP, so only few global observables were studied.

No rare probe search (Heavy flavor, pre-thermal photons etc)Some effort started at SPS, but that too at 1-2 beam energies.

After RHIC people started talking about low energy RHIC run,

(Reanalyzed SPS data are finding that they have also found what RHIC is finding today, even jet-quenching..)

Arguments being given are..

Exploring the QCD Phase-diagram

Matter Density μB (GeV)

Tem

per

atu

re (

MeV

)

Quark-Gluon Plasma

Hadron Gas

Phase Boundary

0

200

0

Atomic Nuclei

1

Critical Point

Susceptibilities diverge near critical point

Locate the critical point using correlation/fluctuation measurements

√s

<(X - <X>)2> Enhanced Fluctuationsnear Critical Point

Rajagopal, Shuryak,Stephanov

Critical Point

Matter Density μB (GeV)

Tem

per

atu

re (

MeV

)

Quark-Gluon Plasma

Hadron Gas

Phase Boundary

0

200

0

Atomic Nuclei

1

Critical Point

Exploring the QCD Phasediagram

Plot from M. Stephanov, Correlations ‘05

Challenge: Guidance on exact location and strength of correlation signals is limited

QCD Phase Diagram

Model predictions:

1) All ‘end points’ exist at B > 0.1GeV

2) Most ‘end points’ exist at B < 0.95GeV

3) Large uncertainties in the predictions. Data is important.

M.A Stephanov, Prog. Theor. Phys. Suppl. 153, 139(2004); Int. J. Mod.

Phys. A20, 4387(05); hep-ph/0402115

pn

++

K

p

e+

e-

Looking into the fireball …

… using penetrating probes:

short-lived vector mesons decaying into electron-positron pairs

SIS18 SIS100/

300

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

We must go back to low energy DETAILED measurements

Understand QCD at high baryon density Critical point and phase transition (critical fluctuations) Chiral Phase transition (Mass modifications) Neutron STAR (strange matter at high baryon density).

The phase diagram of strongly interacting matter(Revisit)

RHIC, LHC: high temperature, low baryon densityFAIR: moderate temperature, high baryon density

Baryon density in central cell (Au+Au, b=0 fm): HSD: mean field, hadrons + resonances + strings QGSM: Cascade, hadrons + resonances + strings

Transport calculations: energy densities

C. Fuchs, E. Bratkovskaya, W. Cassing

Baryon density in central cell (Au+Au, b=0 fm): HSD: mean field, hadrons + resonances + strings QGSM: Cascade, hadrons + resonances + strings

C. Fuchs, E. Bratkovskaya, W. Cassing

Transport calculations: baryon densities

SIS 100 Tm

SIS 300 Tm

Structure of Nuclei far from Stability

cooled antiproton beam:Hadron Spectroscopy

Compressed Baryonic Matter

The future Facility for Antiproton an Ion Research (FAIR)

Ion and Laser Induced Plasmas:

High Energy Density in Matter

low-energy antiproton beam:antihydrogen

Primary beams:1012 /s 238U28+ 1-2 AGeV4·1013/s Protons 90 GeV1010/s U 35 AGeV (Ni 45 AGeV)

Secondary beams:rare isotopes 1-2 AGeVantiprotons up to 30 GeV

Observables:Penetrating probes: , , , J/ (vector mesons)Strangeness: K, , , , , Open charm: Do, D

Hadrons ( p, π), exotica

Experimental program of CBM:

Systematic investigations:A+A collisions from 8 to 45 (35) AGeV, Z/A=0.5 (0.4) p+A collisions from 8 to 90 GeVp+p collisions from 8 to 90 GeVBeam energies up to 8 AGeV: HADES

Large integrated luminosity:High beam intensity and duty cycle,Available for several month per year

Detector requirementsLarge geometrical acceptance good particle identificationexcellent vertex resolutionhigh rate capability of detectors, FEE and DAQ

Compressed Baryonic Matter: physics topics and observables

Search for chiral symmetry restoration at high B

in-medium modifications of hadrons

Observables: , ,

Search for a deconfined phase at high B enhanced strangeness production ? Observables: K, , , , anomalous charmonium suppression ? Observables: charmonium (J/ψ, ψ'), open charm (D0, D)

Probing the equation-of-state at high B

Observables: collective flow of hadrons, particle production at threshold energies (open charm)

Search for the 1. order phase transition & its critical endpoint Observable: event-by-event fluctuations (K/π, pT, ...)

Radiation hard Silicon (pixel/strip) Tracking System in a magnetic dipole field

Electron detectors: RICH & TRD & ECAL: pion suppression better 104

Hadron identification: TOF-RPC

Measurement of photons, π, η, and muons: electromagn. calorimeter (ECAL)

High speed data acquisition and trigger system

The CBM Experiment

Silicon Tracking System (STS)

Our Achievements So far…

(1) PMDs for WA93,WA98, STAR,ALICE, Muon chambers for ALICE

(2) Development of advanced gaseous detector laboratory * Gaseous detector laboratory exist at VECC-SINP and other

collaborating institutes (3) Development of advanced electronics laboratories (MANAS development, a highlight)

(4) Development of large scale computing facilities (Grid computing) (5) Successful International and National Collabotation (VECC,SINP,PU,RU,JU,IOP,AMU,IIT-Bombay)

(6) More than 40 PhD students

Future based on this strong base of experience and expertiseFuture based on this strong base of experience and expertise

Intermediate mass dimuons in p-A collisions• The p-A data is properly described by a superposition of Drell-Yan and DD decays

• The required charm cross-section is consistent with previous direct measurements

_

NA50

From NA50 to NA60 (1996 - 2000)

Improved measurement of prompt dimuon production and

open charm in heavy ion collisions

Let’s add silicon detectors to track the muons before they traverse the hadron absorber

Our ProposalBased on our experience, Aim is to take part SIGNIFICANTLY

• Work with latest detector technology• Application of the expertise in detector development in other fields.

Design, simulate, build and operate complete Muon program

Serious talk started Feb’05 during ICPAQGP, requested for good project. Asked to explore Muon option

42

Detector ChoiceDetector Choice

Silicon Tracker+ Magnet

Muon Absorber + muon stations (Proposed: Mostly Indian effort)

TOF will be placed/absorber will be removed

CBM Much Version - 1

Carbon absorberDetector layers

STSTarget 1200300

50 100 150

Gap between two detector layers = 45

Gap between absorber and adjacent detector layer = 1

Thickness of each detector layer = 10

All dimensions in mm

Study of μ ID system with absorber for CBM

C/Fe absorbers + detector layers

Simulations Au+Au 25 AGeV:

track reconstruction from hits in STS and muon chambers (100 μm position resolution)

muon ID: tracks from STS to muon chamber behind absorber

vector meson multiplicities from HSD transport code

J/ψ→μ+μ-

s/b ~ 100

ρ φω

Much version CV1 CV2 CV3 CV4 CV5Reconstructed Muon tracks (%) from decay

83 58 85 62 83

Reconstructed Muon tracks (%) from J/psidecay

94 91 95 93 95

Absorber thickness in mm.

50,100,200,300,1200 =

1850

150,300,600,900,1200 =

3450

50,100,200,300,1200 =

1850

150,300,600,900,1200 =

3450

300,400,500,650 =

1850

# of detector layers

163 detectors

between absorbers

16 3 detectors

between absorbers

11 2 detectors

between absorbers

112 detectors

between absorbers

13 3 detectors

between absorbers

Reconstruction efficiency of muon tracks through Much only without background

47

Muon Chambers:

Design parameters and method....

•Should be able to handle highest rate

•Should have good position resolution

•Should be possible to make in large area

•FEE connections and taking them out is a concern..

49

Comparison of detectors..

MWPC GEM Micromegas

Rate capability 10^6Hz/cm^2 >5x10^7Hz/cm^2 10^8Hz/cm^2

Gain High 10^6 low 10^3 (single)

> 10^5 (multi GEM)

High > 10^5

Gain stability Drops at 10^4Hz/mm^2

Stable over 5*10^5Hz/mm^2

Stable over 10^6Hz/mm^2

2D Readout ? Not really Yes and flexible Yes, not flexible

Position resolution > 200 µm (analog) 50 µm (analog) Good < 80 µm

Time resolution ~ 100 µs < 100 ns < 100 ns

Magnetic Field effect High Low Low

Cost Expensive, fragile Cheap, robust Cheap, robust

Both GEM & MICROMEGAS are suitable for high rate applications

50

Design concepts..

Wheel type design of planes with 8 sector type chambers in each plane

Each sector with a single woven mesh supported on insulating pillars - - - mechanical problems??

Readout pad granularity to vary from 3mm to 7mm pads radially in 3 zones - to keep occupancy within 10% level

(needs further optimization study)

•VECC-GSI MOU Signed

•Ongoing work by FAIR-utilization committee• (CDR in two months)

•DST-FAIR MOU to be renewed on 24th July’06

•Proposal given by VECC-IOP in XIth plan

•Included as Mega-science project

•Meeting with Secy-DST

• Detailed meeting in October

DAE-Vision on radiation Detector (2004)DAE-Vision on radiation Detector (2004)

Radiation Detector

Quest of knowledgeNeed of Society

NP, HEP, S S Physics experiments

Medical Imaging

High Density Matter (CBM)Neutrino observations (INO)

Detector Vision: need of the society

Common theme: need of the society.Medical diagonesis. X-Ray imaging: GEM, a-Si-films with scintillators, PSDs . PET: RPC

2-D Dosimetry: GEM, RPC.

Worldwide in large accelerator centres dedicated facilities are being built for development of detectors for medical applications eg. Medpix@CERN. Our experience in working with high resolution detector can be used for medical applications.

9 keV absorption radiography using GEM

Precision radiography setup using Si.

PLAN:

Full R&D in XIth plan period30% production cost

R&D (parallel effort on GEM and Micromegas)

•Dedicated Gas detector Lab•Dedicated Electronics Lab with all purpose DAQ system

•ASIC-development

Conclusion

•CBM is complementary to RHIC/LHC•Will address some fundamental questions of QCD

•We propose to take lead role in the experiment

•Experience of developing most advanced detector will help to use them in other areas.

„The challenge for the next century physics is: explain confinement and broken (chiral) symmetry“T.D. LeeT.D. Lee

„But perhaps the most interesting and surprising thing about QCD at high density is that, by thinking about it, one discoversa fruitful new perspective on the traditional problem of confinement and chiral-symmetry breaking”.F. WilczekF. Wilczek

Mapping the QCD phase diagram with heavy-ion collisions

Critical endpoint:Z. Fodor, S. Katz, hep-lat/0402006S. Ejiri et al., hep-lat/0312006μB < 400 MeV: crossover

SIS100/300

ε=0.5 GeV/fm3

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

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

Strongly interacting matter in neutron stars

F. Weber J.Phys. G27 (2001) 465

“Strangeness" of dense matter ?In-medium properties of hadrons ?Compressibility of nuclear matter?

Deconfinement at high baryon densities ?