Experiment at FAIR Compressed Baryonic Matter

1. Experiment at FAIR Compressed Baryonic Matter Exploring Phase Diagram of strongly Interacting Matter using High Energy Heavy Ion Collisions Subhasis Chattopadhyay, VECC

2. OUTLINE • Why high energy heavy ion experiment at FAIR important? • CBM experiment • Why should we participate? • How should we participate? • Travel so far.. • RoadMap

3. States of strongly interacting matter baryons hadrons partons Compression + heating = quark-gluon matter (pion production) Neutron stars Early universe

4. Phase Diagram from cartoon to precise Tool: High energy heavy ion collisions, generate density/temparature

5. 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

6. timeline Courtesy of S. Bass 1 2 3 Initial condition: CGC high-Q2 interactions medium formation hot, dense medium expansion hadronization hadrons hadronic scatterings freeze-out ratios, spectra: freeze-out properties fluctuations, etc. correlations: (1) thermalization? (2) is there conical flow? elliptic flow: does hydro work? what EOS?

7. 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 viscosity • But • Need to have (unequivocal)evidence that • matter is deconfined • Order of Phase Transition (Cross-over)?

8. Our journey: SPS@CERN 2cm x 2cm scintillator 8000 cells WA93 (data taken: 1991) 52000 cells, WA98 (Data taken: 1993-1996)

9. STAR experiment at RHIC, BNL

10. Our understanding so far Quick glimpses

11. Leading hadron suppression Wang and Gyulassy: DE  softening of fragmentation  suppression of leading hadron yield Ivan Vitev, QM02

12. Inclusive yield relative to binary-scaled p+p • d+Au : enhancement • Au+Au: strong suppression • pT=4 GeV/c: • cent/minbias= 1.110.03 • central collisions enhanced wrt minbias Suppression of the inclusive yield in central Au+Au is a final-state effect

13. pedestal and flow subtracted Azimuthal distributions Near-side: p+p, d+Au, Au+Au similar Back-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

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

15. A related question: the initial condition • 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 • Large nucleus (A) at low momentum fraction x  gluon distribution saturates ~ 1/as(QS2) with QS2~ A1/3 • A collision puts these gluons ‘on-shell’ r ~ A xg(x,Q2) / R2 • Parton-hadron maps gluons directly to charged hadrons D. Kharzeev, E. Levin and L. McLerran, Phys. Lett. B 561(2003) 93

16. 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.

17. 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

18. What have we learned (so far)? • Demand an explanation beyond a purely hadronic scenario: • The hydro-models require early thermalization(ttherm< 1fm/c)and high initial energy densitye > 10 GeV/fm3 • Implies the matter is well described as ideal relativistic fluid • Initial gluon density dng/dy~1000 and initial energy densitye~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.

19. Meanwhile, SPS people have started looking at Their data again… Interestingly, many RHIC observations are reproduced and then new ones..

20. The Kink Van-Hove Fluctuation Make more precision measurement at SPS energies. Only Hadronic observables..

21. one more speculation .... critical point hadrons Q G P coexistence phase

22. ENERGY SCAN….

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

24. 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..

25. Exploring the QCD Phase-diagram Susceptibilities diverge near critical point Locate the critical point using correlation/fluctuation measurements Temperature (MeV) Quark-Gluon Plasma 200 Critical Point Critical Point <(X - <X>)2> Enhanced Fluctuations near Critical Point Phase Boundary Hadron Gas Atomic Nuclei 0 0 1 Matter Density μB (GeV) √s Rajagopal, Shuryak, Stephanov

26. Exploring the QCD Phasediagram Critical Point Temperature (MeV) Quark-Gluon Plasma 200 Phase Boundary Hadron Gas Atomic Nuclei 0 Plot from M. Stephanov, Correlations ‘05 0 1 Matter Density μB (GeV) Challenge: Guidance on exact location and strength of correlation signals is limited

27. 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

28.  n  p p  ++ e+ r K e- Looking into the fireball … … using penetrating probes: short-lived vector mesonsdecaying into electron-positron pairs

29. Meson production in central Au+Au collisions W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745 SIS100/ 300 SIS18

30. 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).

31. The phase diagram of strongly interacting matter (Revisit) RHIC, LHC: high temperature, low baryon density FAIR: moderate temperature, high baryon density

32. Transport calculations: energy densities 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

33. Transport calculations: baryon densities 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

34. The future Facility for Antiproton an Ion Research (FAIR) Primary beams: 1012 /s 238U28+ 1-2 AGeV 4·1013/s Protons 90 GeV 1010/s U 35 AGeV (Ni 45 AGeV) Secondary beams: rare isotopes 1-2 AGeV antiprotons up to 30 GeV SIS 100 Tm SIS 300 Tm cooled antiproton beam: Hadron Spectroscopy Ion and Laser Induced Plasmas: High Energy Density in Matter Structure of Nuclei far from Stability low-energy antiproton beam: antihydrogen Compressed Baryonic Matter

35. Experimental program of CBM: Observables: Penetrating probes:, , , J/ (vector mesons) Strangeness:K, , , , , Open charm: Do, D Hadrons ( p, π), exotica Detector requirements Large geometrical acceptance good particle identification excellent vertex resolution high rate capability of detectors, FEE and DAQ Systematic investigations: A+A collisions from 8 to 45 (35) AGeV, Z/A=0.5 (0.4) p+A collisions from 8 to 90 GeV p+p collisions from 8 to 90 GeV Beam energies up to 8 AGeV: HADES Large integrated luminosity: High beam intensity and duty cycle, Available for several month per year

36. Compressed Baryonic Matter: physics topics and observables Probing the equation-of-state at high B Observables: collective flow of hadrons, particle production at threshold energies (open charm) 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) Search for chiral symmetry restoration at high B in-medium modifications of hadrons Observables: , ,  Search for the 1. order phase transition & its critical endpoint Observable: event-by-event fluctuations (K/π, pT, ...)

37. The CBM Experiment Silicon Tracking System (STS)  Radiation hard Silicon (pixel/strip) Tracking Systemin 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

38. Our Achievements So far… • PMDs for WA93,WA98, STAR,ALICE, Muon chambers for ALICE • 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 expertise

39. 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

40. From NA50 to NA60 (1996 - 2000) Let’s add silicon detectors to track the muons before they traverse the hadron absorber Improved measurement of prompt dimuon production and open charm in heavy ion collisions

41. Our Proposal • Based on our experience, • Aim is to take part SIGNIFICANTLY • Work with latest detector technology • Application of the expertise in detector • development in other fields. Serious talk started Feb’05 during ICPAQGP, requested for good project. Asked to explore Muon option Design, simulate, build and operate complete Muon program

42. Detector Choice Muon Absorber + muon stations (Proposed: Mostly Indian effort) Silicon Tracker + Magnet

43. TOF will be placed/absorber will be removed

44. CBM Much Version - 1 Gap between two detector layers = 45 Gap between absorber and adjacent detector layer = 1 Thickness of each detector layer = 10 • Carbon absorber • Detector layers 50 100 150 Target STS 300 1200 • All dimensions in mm

45. Study of μID system with absorber for CBM C/Fe absorbers + detector layers J/ψ→μ+μ- s/b ~ 100 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 ρ ω φ

46. 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.. 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)