CBM The future of relativistiv heavy-ion physics at GSI V. Friese Gesellschaft für Schwerionenforschung Darmstadt, Germany Tracing the Onset of Deconfinement in Nucleus-Nucleus Collisions Trento Workshop April 2004

2 Deconfinement Workshop, Trento, April 2004 V. Friese The planned facility in Darmstadt SIS 100/300 Unilac SIS HESR NESR SuperFRS A "next generation" accelerator facility: Double-ring synchrotron 1100 m circumference 100 / 300 Tm Cooler/Storage rings (CR, NESR, HESR) Experimental areas for:  nuclear structure  plasma physics  antiproton physics  nuclear collisions  atomic physics Existing facility serves as injector

3 Deconfinement Workshop, Trento, April 2004 V. Friese Design Goals Highest beam intensities Excellent beam quality

4 Deconfinement Workshop, Trento, April 2004 V. Friese Design Goals (2) Parallel operation for different physics programmes

5 Deconfinement Workshop, Trento, April 2004 V. Friese Design goals (3) Higher beam energies Heavy-ion beams 2 – 35 AGeV Slow extraction, continuous beam ions/s up to Uranium Light ions (Z/A=1) up to 45 AGeV

6 Deconfinement Workshop, Trento, April 2004 V. Friese Project Status November 2001Conceptual Design Report Cost estimate 675 M € July 2002German Wissenschaftsrat recommends realisation February 2003German Federal Gouvernment decides to build the facility. Will pay 75 % January / April 2004Letters of Intent submitted

7 Deconfinement Workshop, Trento, April 2004 V. Friese Timescale

8 Deconfinement Workshop, Trento, April 2004 V. Friese The Times they are a' changing

9 Deconfinement Workshop, Trento, April 2004 V. Friese The Future GSI and the QCD Phase Diagram nuclei hadronic phase SPS RHIC SIS300 lattice QCD : Fodor / Katz, Nucl. Phys. A 715 (2003) 319 dilute hadron gas dense bayonic medium... operating at highest baryon densities... maybe reaching deconfinement... maybe close to the critical point

10 Deconfinement Workshop, Trento, April 2004 V. Friese Why another experiment? We have data from AGS ( - 12 AGeV) and SPS (20 AGeV - ) but :  studying the dense hadronic phase requires penetrating probes: dileptons  studying the onset of deconfinement requires systematic (energy, system size) measurements of hadronic observables The qualitatively new feature of the future accelerator: Highest beam intensities (10 9 ions/s) give access to rare probes (ρ,  dileptons, Ω, D, J/Ψ)

11 Deconfinement Workshop, Trento, April 2004 V. Friese 1. In-medium modifications of hadrons  onset of chiral symmetry restoration at high  B measure: , ,   e + e - open charm (D mesons) 2. Indications for deconfinement at high  B  enhanced strangeness production ? measure: K, , , ,   charm production ? measure: J/ , D  softening of EOS measure flow excitation function 3. Critical point  event-by-event fluctuations 4. Color superconductivity  precursor effects at T>T c ? Physcis Topics and Observables

12 Deconfinement Workshop, Trento, April 2004 V. Friese A physics example : Charm production Hadron gas in chemical equilibrium Canonical suppression analoguous to strangeness Equilibrated QGP + statistical coalescence Gorenstein et al J. Phys. G 28 (2002) 2151 Predictions of open charm yield differ by orders of magnitude for different production scenarios, especially at low energies Soft A dependence : ~ ~ N p pQCD : ~ A 2 ~ N p 4/3

13 Deconfinement Workshop, Trento, April 2004 V. Friese Open charm in dense matter Various QCD inspired models predict a change of D mass in hadronic medium Mishra et al, nucl-th/ Substantial change (several 100 MeV) already at  =  0 In analogy to kaon mass modification, but drop for both D + and D - Effect for charmonium is substantially smaller

14 Deconfinement Workshop, Trento, April 2004 V. Friese Reduced D meson mass : consequences If the D mass is reduced in the medium: DD threshold drops below charmonium states Mishra et al, nucl-th/ Decay channels into DD open for  ’,  c, J/   broadening of charmonium states  suppression of J/   enhancement of D mesons HSD : D yield enhanced by a factor of 7 at 25 AGeV! Cassing et al, Nucl. Phys. A 691 (2001) 753

15 Deconfinement Workshop, Trento, April 2004 V. Friese Caveats and Advantages Only one slot for relativistiv nuclear collisions at future GSI Build an "universal experiment" for both hadronic and leptonic probes, covering as many obervables as possible High beam intensity, quality and duty cycle High availability due to parallel operation of accelerator Possibility of systematic measurements: beam energy (10 – 35/45 AGeV) system size even of very rare probes!  

16 Deconfinement Workshop, Trento, April 2004 V. Friese Challenges : rare probes in heavy-ion environment 25 AGeV W. Cassing et al, Nucl. Phys. A 691(2001) 753 charge muliplicity ≈ 1000 D multiplicity – need : high event rates highly selective trigger

17 Deconfinement Workshop, Trento, April 2004 V. Friese Conditions and requirements High track multiplicity ( ) Beam intensity 10 9 ions/sec. High interaction rate (10 MHz) Detector tasks: Tracking in high-density environmentSTS + TRD Reconstruction of secondary vertices (resolution  50  m)STS Hadron identification :  / K / p separation (  t  80 ps) TOF Lepton identification :  / e separation (pion suppression )TRD + RICH Myon / photon measurements ECAL central 25 AGeV, UrQMD + GEANT Need fast and radiation hard detectors

18 Deconfinement Workshop, Trento, April 2004 V. Friese The CBM detector Setup in GEANT4

19 Deconfinement Workshop, Trento, April 2004 V. Friese Tracking System Radiation hard Silicon pixel/strip detectors magnet Requirements: Radiation hardness Low material budget Fast detector response Good positon resolution Monolothic Active Pixel Sensors Pitch 20  m Low material budget : Potentially d = 20  m Excellent single hit resolution :  3  m S/N =

20 Deconfinement Workshop, Trento, April 2004 V. Friese Tracking reconstructed tracks Reconstruction efficiency > 95 % Momentum resolution ≈ 0.6 %

21 Deconfinement Workshop, Trento, April 2004 V. Friese Hadron identification σ TOF = 80 ps Bulk of kaons (protons) can well be identified with σ TOF = 80 – 100 ps

22 Deconfinement Workshop, Trento, April 2004 V. Friese RPC developments for TOF 90 cm-14 strips-4 gaps  t < 80 ps Tail < 2% Detector resolution R&D FOPI Upgrade Challenge for TOF : Huge counting rate (25 kHz/cm 2 ) Large area (130 m 10 m)

23 Deconfinement Workshop, Trento, April 2004 V. Friese TRD Duties e/  separation tracking Requirements hit rate up to 500 kHz per cell fast readout (10 MHz) Anticipated setup 9 layers in three stations (z = 4m / 6m / 8m) area per layer 25 / 50 / 100 m 2 channels per layer 35 k / 55 k / 100 k Readout options : drift chamber / GEM / straw tubes For most of the system state-of-the art (ALICE) is appropriate. For the inner part, R&D on fast gas detectors in progress

24 Deconfinement Workshop, Trento, April 2004 V. Friese TRD Wire chamber readout studied at GSI requires small drift times  thin layers  more layers Pion efficiency of < 1% reachable with 9 layers extrapolated from single ALICE-type chamber

25 Deconfinement Workshop, Trento, April 2004 V. Friese RICH Duties e/  separation K/  separation ? vertical plane horizontal plane Optical layout for RICH1 Mirror: Beryllium / glass Two focal planes (3.6 m 2 ) separated vertically

26 Deconfinement Workshop, Trento, April 2004 V. Friese RICH Radiator gas: C 4 H 10 + N 2 (  thr = 16 – 41) Photodetectors: photomultipliers or gas detectors RICH1:  thr = 41  p ,thr = 5.7 GeV  (almost) hadron blind

27 Deconfinement Workshop, Trento, April 2004 V. Friese RICH Option for RICH2 ?  thr = 30  p ,thr = 4.2 GeV, p K,thr =15 GeV Problem: Ring finding in high hit density environment Kaon ID by RICH for p > 4 GeV would be desirable Kaon ID by TOF deteriotes quickly above 4 GeV

28 Deconfinement Workshop, Trento, April 2004 V. Friese DAQ / Trigger Architecture clock Practically unlimited size Max. latency uncritical Avr. latency relevant Detector Front end ADC Buffer memory Event builder and selector Self triggered digitization: Dead time free Each hit transported as Address/Timestap/Value Compensates builder/selector latency Use time correlation of hits to define events. Select and archive. Challenge : reconstruct 1.5 x 10 9 track/sec. data volume in 1 st level trigger  50 Gbytes/sec.

29 Deconfinement Workshop, Trento, April 2004 V. Friese Feasibility study : open charm Key variable to suppress background: secondary vertex position D 0  K -  + (central 25 AGeV) c  = 124  m, BR = 3.8 % BG suppression 2 x 10 5 Assuming = : S/B  1 SNR = 3 at 2 x 10 6 events detection rate 13,000 / h Similar study for D +  K -  +  + (c  = 315  m, BR = 9 %) First estimate S/B  3 Crucial detector parameters: Material in tracking stations Single hit resolution

30 Deconfinement Workshop, Trento, April 2004 V. Friese Feasibility study: J/   e + e - Extremely rare signal! Background from various sources: Dalitz, conversion, open charm... Very efficient cut on single electron p T S/B > 1 should be feasible

31 Deconfinement Workshop, Trento, April 2004 V. Friese Feasibility study : Light vector mesons Background sources: Dalitz, conversion no easy p T cut; sophisticated cutting strategy necessary depends crucially on elimination of conversion pairs by tracking and charged pion discrimination by RICH and TRD (10 4 ) S/B = 0.3 (ρ+  ) S/B = 1.2 (  ) idealised: no momentum resolution

32 Deconfinement Workshop, Trento, April 2004 V. Friese Croatia: RBI, Zagreb Cyprus: Nikosia Univ. Czech Republic: Czech Acad. Science, Rez Techn. Univ. Prague France: IReS Strasbourg Germany: Univ. Heidelberg, Phys. Inst. Univ. HD, Kirchhoff Inst. Univ. Frankfurt Univ. Mannheim Univ. Marburg Univ. Münster FZ Rossendorf FZ Jülich GSI Darmstadt Russia: CKBM, St. Petersburg IHEP Protvino INR Troitzk ITEP Moscow KRI, St. Petersburg Kurchatov Inst., Moscow LHE, JINR Dubna LPP, JINR Dubna LIT, JINR Dubna Obninsk State University PNPI St. Petersburg SINP, Moscow State Univ. Spain: Santiago de Compostela Univ. Ukraine: Shevshenko Univ., Kiev University of Kharkov USA: LBNL Berkeley Hungaria: KFKI Budapest Eötvös Univ. Budapest Italy: INFN Catania INFN Frascati Korea: Korea Univ. Seoul Pusan Univ. Norway Univ. of Bergen Poland: Krakow Univ. Warsaw Univ. Silesia Univ. Katowice Portugal: LIP Coimbra Romania: NIPNE Bucharest The CBM Collaboration

33 Deconfinement Workshop, Trento, April 2004 V. Friese Summary CBM will operate at the future facility from 2012 on It will measure nucleus-nucleus collisions from 10 – 35 / 45 AGeV at interaction rates of 10 MHz The key observables will be rare probes like multiple strange hyperons, open and hidden charm and dileptonic decays of light vector mesons These will (hopefully) give insight into the properties of baryonic matter at extreme densities and into the transition to a deconfined state (Still) open for new ideas! The collaboration has been formed; detector R&D is started or starting CDR : November 2001, LoI : January 2004 Next milestone: Progress Report 2004 / 2005