VolkerFrieseSFAIR_Lund_Friese

					Perspectives for Heavy Ion Reactions
              At FAIR




Volker Friese

    v.friese@gsi.de




   2nd Swedish Workshop on FAIR Physics, Lund, 13. September 2005
                   What the accelerator will give us


                                                                                  SIS 100/300




 Heavy-ion beams up to 35 AGeV
 Light-ion beams up to 45 AGeV
 p beam up to 90 GeV
 Intensity 109 / s
 High availability

   Volker Friese     2nd Swedish Workshop on FAIR Physics, Lund, September 2005                 2
                                      Phases of strongly interacting matter
Heating (pion production)




                                                                       Compression


                            Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005   3
               Cold and dense matter in neutron stars




                           “Strangeness" of dense matter ?
                         In-medium properties of hadrons ?
                          Compressibility of nuclear matter?
                       Deconfinement at high baryon densities ?




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




       Volker Friese       2nd Swedish Workshop on FAIR Physics, Lund, September 2005   4
                Mapping the QCD phase diagram
                                                                       at high collision
                                                                      energies: crossover
                                                                      hadron gas → QGP (top
                                                                      SPS, RHIC, LHC)
                                                                       lower energies: 1st order
                                                                      phase transition
                                                                       separated by critical
                                                                      point
                                                      ε=0.5 GeV/fm3
                                                                        Freeze-out points on
                                                                       smooth curve
                                                                        Close to phase border
                                                                       from top SPS on
                                                                        Strongly interacting
                                                                       hadronic phase at lower
                                                                       energies (?)
Volker Friese     2nd Swedish Workshop on FAIR Physics, Lund, September 2005               5
                The critical point in lattice QCD




                                                             maximal baryon number
                                                             susceptibility at TC for q = TC
                                                             (B  500 MeV)
                                                             → baryon number density
                                                             fluctuations




Volker Friese     2nd Swedish Workshop on FAIR Physics, Lund, September 2005             6
                 Trajectories of heavy ion collisions



                                                              3-fluid hydrodynamics with
                                                             hadron gas EOS

                                                              Phase boundary is reached
                                                             already with 10 AGeV

                                                              30 AGeV hits critical point




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


 Volker Friese         2nd Swedish Workshop on FAIR Physics, Lund, September 2005        7
        Existing data: Onset of deconfinement
                Gazdzicki, Gorenstein,
                                         NA49
          Act. Phys. Polon. B 30 (1999) 2705 (QM 2004) et al., Braz. J. Phys. 34 (2004) 322
                                                  Hama




         peak in strange/nonstrange yield ratio
         plateau of kaon slopes at SPS
         not satisfactorily explained in hadronic scenarios
       can be modeled assuming 1st order phase transition, onset at 30 AGeV

Volker Friese         2nd Swedish Workshop on FAIR Physics, Lund, September 2005              8
                               Critical fluctuations

Event-by-event analysis by NA49: 5% most central Pb+Pb collisions at 158 AGeV




  Dynamical fluctuations in K/π increase towards lower collision energies

     Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005   9
                        J/ψ suppression at top SPS
                NA50, QM 2005




                                                                   "anomalous" suppression
                                                                  observed at top SPS (NA50)

                                                                   indication for QGP (?)

                                                                   no data at lower energies
                                                                  available !

                                                                   can onset be seen?




Volker Friese          2nd Swedish Workshop on FAIR Physics, Lund, September 2005            10
                  Probing the dense fireball




                                                          n
                                            
                                   p                           p
                                       ++             r                          e+
                                   
                                            K


                                                                             e-

using penetrating probes: short lived vector mesons → e+e- pairs


Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005             11
                   Low-mass e+e- spectroscopy

                                                                                No data below 40
                                                                                AGeV

                                                                                Maximum effect
                                                                                at highest baronic
                                                                                density

                                                                                need high
                                                                                precision, high
                                                                                statistics data



Excess of low-mass pairs over hadronic cocktail (CERES)
In-medium modification of ρ ?
Low statistics and resolution
   Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005              12
                                   Open charm near threshold
W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745
                                                                                          extremely low
                                                                                         multiplicity
                                                                                          sensitive to production
                                                                                         mechanism
                                                                                          expected to change mass
                                                                                         in medium
                                                                                          no data in HI collisions!




              SIS18        SIS100/
                              300

           Volker Friese           2nd Swedish Workshop on FAIR Physics, Lund, September 2005               13
                            Charm in dense matter
                Mishra et al, nucl-th/0308082                                     D meson masses are
                                                                                  expected to drop in dense
                                                                                  environment

                                                                                  should have strong effect
                                                                                  on production yield



                    Cassing et al,
                    Nucl. Phys. A 691 (2001) 753




Volker Friese        2nd Swedish Workshop on FAIR Physics, Lund, September 2005                   14
                                         Physics topics

                 ?                                                                     !
                                                                   strangeness (K, Λ, Σ, Ξ, Ω)
 deconfinement at high ρB                                                charm (J/ψ, D)
                                                                              flow



    in-medium properties                                                          ρ, ω, φ → e+e-
         of hadrons                                                                open charm




            critical point                                                        fluctuations



Volker Friese        2nd Swedish Workshop on FAIR Physics, Lund, September 2005                    15
                              Diagnostic probes

                                    Urqmd, U+U, 23 AGeV




Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005   16
               Why we go back to intermediate energies


• Existing data (AGS, RHIC) do not allow an unambiguous
  interpretation of the collision dynamics
• Go on step beyond with a next-generation experiment (and
  accelerator)
   – highest interaction rates → access to rare probes
   – high availability → systematic studies (collision energy,
     system size)
   – large acceptance → complete rapidity coverage
• exploit newest detector technologies
• measure hadronic as well as leptonic observables


   Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005   17
                      CBM: Detector considerations

                                                                      high interaction rates
                rare observables                                      (beam intensity 109/s,
                   (Ω, J/ψ, D)                                           high availability)



       fast detector                        radiation hard
         response                                                                      efficient online
                                            detectors and
        and readout                                                                    event selection
                                             electronics




      STS                 TOF                        RICH                        TRD               ECAL
     tracking,                                                                                    lepton ID
                        hadron ID                 electron ID                electron ID
displaced vertices                                                                                 photons


                + large and uniform acceptance

      Volker Friese     2nd Swedish Workshop on FAIR Physics, Lund, September 2005                    18
                  CBM: Baseline detector concept


                                                            TOF                     ECAL
                                                           (10 m)                   (12 m)
                                      RICH
                                     (1,5 m)

                     magnet



      beam




                                                                      TRDs
                                                                    (4,6,8 m)


                     STS
                ( 5 – 100 cm)


Volker Friese          2nd Swedish Workshop on FAIR Physics, Lund, September 2005            19
                                    Extreme conditions

  Central Au+Au collision at 25 AGeV:
  URQMD + GEANT4

  160 p, 400 -, 400 +, 44 K+, 13 K-,....


 107 Au+Au reactions/sec
   (beam intensities up to 109 ions/sec,
   1 % interaction target)
 determination of (displaced) vertices
  with high resolution ( 50 m)
 identification of electrons and hadrons

   Simultaneous measurement of all observables is not
   possible:
   optimized beam intensities and dedicated subdetectors
        Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005   20
                   Unprecedented requirements

• Challenges for detectors and readout:
   – high rate capability
   – fast detector response and readout
   – radiation hardness
   – high precision
   – low material budget
• No existing technology meeets the requirements
• R&D is needed and ongoing, e.g.
   – radiation hard silicon tracker
   – fast gaseous detectors (TRD, RPC)

   Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005   21
                                   The Silicon Tracking System
                                                                 7     "minimal setup":
                                                     6
                                                                       3 pixel stations
                                        5                              4 strip stations
 pixel detectors                            strip detectors
   vertexing                   4

                   3
          2
      1




      vacuum

z = 5,10,(20) cm

                                                                                momentum resolution < 1 %
                               z = (20),40,60,80,100 cm


 alternative options (including hybrid pixels for track seed) under investigation
               Volker Friese        2nd Swedish Workshop on FAIR Physics, Lund, September 2005              22
                  R&D: Silicon pixel detectors

Close to target (5 cm), vertex resolution ≈ 50 μm needed
Key issues: Material budget, resolution, speed, radiation tolerance

        Mimosa IV                            R&D on MAPS at IReS Strasbourg
                                              thickness < 100 μm
                                              resolution 3 μm
                                              readout frame several μs
                                              rad. tolerance




  Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005   23
                                     R&D on fast TRD
Key issues: Fast → Thin radiator and converter, high rates

 •   Developments by GSI, Bucharest, Dubna
 •   First beam test of prototypes at GSI in summer 2004
 •   Different readouts (MWPC, GEM)
 •   Encouraging results: Stable up to 70 / 100 kHz/cm2




                       MWPC (Dubna)                                           GEM (Dubna)



      Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005            24
                        R&D on large-area timing RPCs
Design goals:
• Time resolution ≤ 80 ps
• Rate capability up to 20 kHz/cm2
                                                R&D in GSI/Heidelberg, Coimbra
• Efficiency > 95 %                             prototype tests encouraging
• Large area  100 m2                           alternative options (window glass,
• Long term stability                          ceramic) under investigation

Prototype with plastic electrodes (109 Ωcm)                       RPC prototype with phosphate glass




        Volker Friese    2nd Swedish Workshop on FAIR Physics, Lund, September 2005              25
                Benchmark observable: D mesons


                                                     Simulation: STS only (no PID)
                                                     with MAPS
                                                     full track reconstruction,
                                                     secondary vertex determination




Challenge: Implementation of
secondary vertex cut in online
event selection (reduction ≈
1000 needed)

                                                            1011 events

Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005        26
                The CBM Physics Working Group
                    established June 2005




Volker Friese     2nd Swedish Workshop on FAIR Physics, Lund, September 2005   28
                                               Summary
• FAIR will offer the opportunity for an exiting physics programme
  for heavy-ion collisions from 2014 on
• Experimental conditions (beam intensity, machine availablity) will
  be unprecedented
• The physics will cover
   – hadrons in dense matter
   – deconfinement at high net baryon density
   – critical point
• The experimental conditions are extreme. R&D on fast, radiation
  hard and precise detectors is under way
• Feasibility studies, event reconstruction and development of analysis
  software are advancing

    Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005   29
                                      CBM: Status

                                          Nov. 2001: FAIR Conceptual Design Report

                                          Jul. 2002: FAIR Recommendation by german
                                          Wissenschaftsrat

                                          Feb. 2003: approved by BMBF

                                          Jan. 2004: CBM Letter of Intent

                                          Jan. 2005: CBM Technical Status Report


                                           Next step: Technical Proposal (ca. 2 years)

                                           First beam on target in 2014




Volker Friese   2nd Swedish Workshop on FAIR Physics, Lund, September 2005           30
                                   The CBM collaboration

Croatia:                                    Hungaria:                                    Romania:
RBI, Zagreb                                 KFKI Budapest                                NIPNE Bucharest
                                            Eötvös Univ. Budapest
Cyprus:                                                                                  Russia:
Nikosia Univ.                               Italy:                                       CKBM, St. Petersburg
                                            INFN Frascati                                IHEP Protvino
Czech Republic:                                                                          INR Troitzk
Czech Acad. Science, Rez                    Korea:                                       ITEP Moscow
Techn. Univ. Prague                         Korea Univ. Seoul                            KRI, St. Petersburg
                                            Pusan National Univ.                         Kurchatov Inst., Moscow
France:                                                                                  LHE, JINR Dubna
IReS Strasbourg                             Norway:                                      LPP, JINR Dubna
                                            Univ. Bergen                                 LIT, JINR Dubna
Germany:                                                                                 PNPI Gatchina
Univ. Heidelberg, Phys. Inst.               Poland:                                      SINP, Moscow State Univ.
Univ. HD, Kirchhoff Inst.                   Jagiel. Univ. Krakow
Univ. Frankfurt                             Silesia Univ. Katowice                       Spain:
Univ. Mannheim                              Warsaw Univ.                                 Santiago de Compostela Univ.
Univ. Marburg                               Warsaw Tech. Univ.
Univ. Münster                                                                            Ukraine:
FZ Rossendorf                               Portugal:                                    Univ. Kiev
GSI Darmstadt                               LIP Coimbra




    Volker Friese           2nd Swedish Workshop on FAIR Physics, Lund, September 2005                              31

				
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