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THE MUON DETECTION SYSTEM FOR THE CBM EXPERIMENT AT FAIR/GSI

Learn about the muon detection system layout and feasibility studies for CBM experiment at FAIR/GSI, focusing on observables like ρ,ω,φ and J/ψ. Discover insights on dense matter in heavy ion collisions and astrophysics.

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THE MUON DETECTION SYSTEM FOR THE CBM EXPERIMENT AT FAIR/GSI

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  1. THE MUON DETECTION SYSTEM FOR THECBMEXPERIMENT ATFAIR/GSI A. Kiseleva Helmholtz International Summer School Dense Matter In Heavy Ion Collisions and Astrophysics (DM2008) July 14 – 26, 2008

  2. Outline • FAIR project • CBM experiment: • setup • observables • The muon detection system for CBM • layout • feasibility studies for: • ρ, ω, φ • J/ψ • Conclusions and next steps

  3. FAIR: the international Facility for Antiproton and Ion Research GSI: Gesellschaft für Schwerionenforschung GSI/FAIR

  4. FAIR: the international Facility for Antiproton and Ion Research primary beams • 5∙1011/s; 1.5-2 GeV/u; 238U28+ • factor 100-1000 increased intensity • 4x1013/s 90 GeV protons • 1010/s 238U 35 GeV/u (Ni 45 GeV/u) secondary beams • rare isotopes 1.5 - 2 GeV/u; • factor 10 000 increased intensity • antiprotons 3(0) - 30 GeV storage and cooler rings accelerator technical challenges • beams of rare isotopes • e – A Collider • 1011 stored and cooled antiprotons • 0.8 - 14.5 GeV • rapidly cycling superconducting magnets • high energy electron cooling • dynamical vacuum, beam losses

  5. Research programs at FAIR Rare isotope beams: nuclear structure and nuclear astrophysics nuclear structure far off stability nucleosynthesis in stars and supernovae • Beams of antiprotons: hadron physics • quark-confinement potential • search for gluonic matter and hybrids • hypernuclei • Nucleus-nucleus collisions: compressed baryonic matter • baryonic matter at highest densities (neutron stars) • phase transitions and critical endpoint • in-medium properties of hadrons • Short-pulse heavy ion beams: plasma physics • matter at high pressure, densities, and temperature • fundamentals of nuclear fusion • Atomic physics, FLAIR, and applied research • highly charged atoms • low energy antiprotons • radiobiology • Accelerator physics • high intensive heavy ion beams • dynamical vacuum • rapidly cycling superconducting magnets • high energy electron cooling • Nucleus-nucleus collisions: compressed baryonic matter • baryonic matter at highest densities (neutron stars) • phase transitions and critical endpoint • in-medium properties of hadrons CBM experiment

  6. Physics case heat Predictions from lattice QCD: • crossover transition from partonic to hadronic matter at small mB and high T • critical endpoint in intermediate range of the phase diagram • first order deconfinement phase transition at high mB but moderate T compression

  7. CBM physics topics and abservables • In-medium modifications of hadrons • onset of chiral symmetry restoration at high densities ρB • measure: ρ, ω, φ → e+e- / μ+μ- • open charm (D mesons) • Strangeness in matter (strange matter?) • enhanced strangeness production ? • measure: K, Λ, Σ, Ξ. Ω • Indications for deconfinement at high ρB • anomalous charmonium suppression ? • measure: J/ψ, ψ' → e+e- / μ+μ-, D0 → Kπ, D±→ Kππ • softening of EOS • measure flow excitation function • Critical point • event-by-event fluctuations • Color superconductivity • precursor effects ?

  8. Dilepton sources in heavy-ion collisions Investigation of dense baryonic matter using penetrating probes In-medium modifications of low-mass vector mesons: • shift ? • broadening ? • melting ? • ... ? Searching for the onset of deconfinement • J/ψ dissociation in the QGP ? • sequential melting of ψ’ and J/ψ ? • modifications of pt distribution ? • collective flow of charmonium ? • … ?

  9. Yields for central Au+Au at 25 AGeV CBM π+ φ J/ψ multiplicity branching ratio (μμ) pion-to-charmonium ratio ~ 109 ! yield per event W. Cassing, E. Bratkovskaya, A. Sibirtsev Nucl. Phys. A 691 (2001) 745

  10. Experimental requirements • high statistics • large signal-to-background ratio • good mass resolution • large acceptance • high reconstruction efficiency Central Au+Au collision at 25 AGeV (UrQMD + GEANT3) 160 p 400 - 400 + 44 K+ 13 K- • up to 107 Au+Au reactions/sec (beam intensities up to 109 ions/s with 1 % interaction target) • determination of (displaced) vertices with high resolution ( 50 m) • identification of leptons and hadrons

  11. STS MuCh TRD ToF CBM for dimuon measurements STS track, vertex and momentum reconstruction MuCh muon identification TRD global tracking RPC-ToF time-of-flight measurement GEANT3 model STS Measurements: charmonium – standard MuCh (13.5λI) low-mass vector mesons – compact MuCh (7.5λI)

  12. Muon detector segmentation 5% occupancy min pad 1.4  2.8 mm2 space resolution: x – 400 μm, y – 800 μm max pad 44.8  44.8 mm2 space resolution: x – 12.8 mm, y – 12.8 mm Mikhail Ryzhinskiy, Saint-Petersburg State Polytechnical University

  13. Simulations • Signals: multiplicities from Hadron-String Dynamics (HSD) • ρ, ω, φ, η and ηDalitz • J/ψ, Ψ' • Background: Ultrarelativistic Quantum Molecular Dynamics (UrQMD) • central Au+Au at 25 AGeV www.th.physik.uni-frankfurt.de/~brat/hsd.html www.th.physik.uni-frankfurt.de/~urqmd/

  14. Muon reconstruction μ+ J/ψ μ- S. Gorbunov, Kirchhoff Inst. f. Physik, Universität Heidelberg I. Kisel, GSI

  15.  background signals  ρ ω  φ  η ηDalitz Results Central Au+Au collisions at 25 AGeV Signal-to- Efficiency Mass Background (%) resolution (S/B) ratio (MeV) ω 0.09 2 10 φ 0.03 4 12 J/ψ 18 13 21 Ψ' 0.8 16 27  background signals  J/ψ  Ψ'

  16. Analysis of background composition Central Au+Au collisions at 25 AGeV compact MuCh (7.5λI) standard MuCh (13.5λI) Masse of particles: μ – 106 MeV, π – 140 MeV, Κ – 498 MeV, p – 938 MeV

  17. m2 = β = γ = m2 = P2 ( - 1) P (GeV/c) 1 P2 β2 (β × γ)2 L 1 c × t √1 – β2 m2 (GeV2/c4) Background rejection via mass determination (L, t) → β ToF

  18. 610-3 510-4 S/B ratio eff.% 0.09 2.0 0.03 4.1 S/B ratio eff.% 0.17 1.5 0.06 3.0 ω φ Improved results with pIDToF Central Au+Au collisions at 25 AGeV compact MuCh (7.5λI) without ToF with ToF

  19. Results for different collision systems * in order to increase the acceptance of reconstructed ω we can use different type of tracks

  20. Study of possible detector solutions Detector requirements: • high rate capability (up to 1 MHz/cm2) • high granularity (up to 1 hit/cm2s-1 for central Au+Au collisions) • position resolution < 300 μm Detector options: • GEM(Gas Electron Multiplier) • Micromegas(Micro Mesh Gaseous Detector)

  21. LHE JINR Dubna Pads Readout electronics PCB Argon Spacer Support structure GEM foils Fasteners PNPI St. Petersburg VECC Kolkata Detector prototypes: GEMs

  22. Conclusions • Promising results for low-mass vector mesons • Good result for J/ψ • ψ' identification seems possible

  23. Next steps • Implementation of muon trigger • Realistic detector response: • clustering • realistic detector inefficiency • Muon system optimization: • necessary number of detector layers • additional absorber in STS • detector resolution study

  24. China Croatia Cyprus Czech Republic France Germany Hungaria India Korea Norway Poland Portugal Romania Russia Ukraine Thank you for your attention! 52 institutions, more than 400 members (May 2008) www.gsi.de/fair/experiments/CBM/index.html

  25. Signal acceptance Central Au+Au collisions at 25 AGeV J/ψ→μ+μ- Pluto STS 1m Fe ρ→μ+μ- Pluto STS 1m Fe

  26. Signal parameters: J/ψ (central Au+Au at 25AGeV) 2 J/ψ Bg Bg J/ψ

  27. Signal parameters: ρ0 (central Au+Au at 25AGeV) 2 ρ0 Bg Bg ρ0

  28. Hard-soft pairs ρ0→μ+μ- — hard-hard (h-h) pairs — hard-soft (h-s) pairs — h-h + h-s μhard μsoft

  29. Digitization algorithm primary electrons sec. electrons Advanced digitization and cluster finding in MuCh, M. Ryzhinskiy

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