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Centrality Determination and Reaction plane reconstruction with MPD

Centrality Determination and Reaction plane reconstruction with MPD. D.Dryablov, V. Zhezher, M.Kapishin, G.Musulmanbekov. Topics. Motivation Event Generators MPD Layout Reaction Plane Reconstruction with ExtZDC Definitions MC estimation of efficiency of ExtZDC

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Centrality Determination and Reaction plane reconstruction with MPD

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  1. Centrality Determination and Reaction plane reconstruction with MPD D.Dryablov, V. Zhezher, M.Kapishin,G.Musulmanbekov XIV GDRE Workshop, Dubna 12 - 14 December 2012

  2. Topics • Motivation • Event Generators • MPD Layout • Reaction Plane Reconstruction with ExtZDC • Definitions • MC estimation of efficiency of ExtZDC • Determination of Centrality • by TPC • by ExtZDC • Results of RP reconstruction • Plans for the Future XIV GDRE Workshop, Dubna 12 - 14 December 2012

  3. Motivation: Why do we need RP reconstruction? • Physics Tasks at semi-central nucleus-nucleus collisions: • Elliptic Flow of mesons, nucleons and hyperons, hypernuclei • Direct Flow of nucleons, hyperons and hypernuclei • Femtoscopy Correlations w.r.t. RP • Global polarization (w.r.t. RP) of hyperons (Λ, Ξ, Ω) • Vector mesons alightment w.r.t. RP , measured by dilepton yield asymmety • Charge asymmetry w.r.t. RP, CME • Selection of • Semi-central collisions  Centrality Determination XIV GDRE Workshop, Dubna 12 - 14 December 2012

  4. Event Generators: UrQMD vs LAQGSM UrQMD QGSM QGSM UrQMD XIV GDRE Workshop, Dubna 12 - 14 December 2012

  5. Event Generators • LAQGSM K. Gudima et al. LA-UR-01-6804 • minbias events: 105 for √s = 3, 5, 7, 9, 11 GeV • semi-central events: 105 for √s = 7 GeV • GLISSANDO – GlauberMC W. Broniowski et al., CPC, 2008 • any statistics at any energy • In prospect: • UrQMD add-on: A. Polanski, G. Musulmanbekov, ISHEPP’2012 • residual nucleus • evaporation • multifragmentation XIV GDRE Workshop, Dubna 12 - 14 December 2012

  6. Last MPD layout ExtZDC ExtZDC Length of TPC -340 cm, D=300cm XIV GDRE Workshop, Dubna 12 - 14 December 2012

  7. “Old” and Extended ZDC cell 10 x 10 (cm x cm) XIV GDRE Workshop, Dubna 12 - 14 December 2012

  8. Extended ZDC detector y ExtZDC • Simulation of Extended ZDC within mpdroot: • L ≈ 120 cm • 5 < R < 61 cm (radius of the inscribe circle) • dcell = 10x10 cm • z0 = 365 cm (distance from the int. point to ZDC) • 0.8o < θ < 9.3o (covered zenith angle) • 2.5 < η < 5.0 (covered pseudorapidity range) x XIV GDRE Workshop, Dubna 12 - 14 December 2012

  9. py px z y y x x Reaction Plane: Definitions Reaction plane defined by (1) beam direction and (2) impact parameter initial spatial anisotropy anisotropy in momentum space 3/4 /4 “In-plane” region “Out-of-plane” region -3/4 -/4 XIV GDRE Workshop, Dubna 12 - 14 December 2012

  10. Definitions: Flows ψR 1-st Fourier harmonics → directed flow 2-nd Fourier harmonics → elliptic flow XIV GDRE Workshop, Dubna 12 - 14 December 2012

  11. Definitions: Reaction Plane reconstruction ShinIchi Esumi y y Reaction plane Reaction plane i 1 2 x x i plane with the directed moment plane with the elliptic moment Σ wi*sin(i) Σ wi*sin(2i) tan(1) = tan(22) = Σ wi*cos(i) Σ wi*cos(2i) (wi: 1 or pT) XIV GDRE Workshop, Dubna 12 - 14 December 2012

  12. Reaction Plane reconstruction with ExtZDC y ExtZDC x Method 1: ; Method 2: XIV GDRE Workshop, Dubna 12 - 14 December 2012

  13. Problem of identification:directed flows of pions and nucleons have opposite signs !So are orientations of RPs defined by them! XIV GDRE Workshop, Dubna 12 - 14 December 2012

  14. ΔΨR vs impact parameter 200 GeV ­ Selection of Semi-Central Events XIV GDRE Workshop, Dubna 12 - 14 December 2012

  15. Reaction Plane Reconstruction 3 GeV ­ ExtZDC acceptance XIV GDRE Workshop, Dubna 12 - 14 December 2012

  16. Extended ZDC detector 5 GeV ­ ExtZDC acceptance XIV GDRE Workshop, Dubna 12 - 14 December 2012

  17. Extended ZDC detector 7 GeV ­ ExtZDC acceptance XIV GDRE Workshop, Dubna 12 - 14 December 2012

  18. Extended ZDC detector 9 GeV ­ ExtZDC acceptance XIV GDRE Workshop, Dubna 12 - 14 December 2012

  19. Extended ZDC detector 11 GeV ­ ExtZDC acceptance XIV GDRE Workshop, Dubna 12 - 14 December 2012

  20. Selection of events by centrality in TPC Impact parameter b: 0 - 3 fm 3 – 6 fm 6 – 9 fm 9 – 12 fm Fraction of σincltot : 0 - 5% 5 – 15% 15 – 30% 30 – 60% Total multiplicity of charged tracks is a measure of impact parameter b (and centrality of nucleus-nucleus interaction) Semi-Central Events XIV GDRE Workshop, Dubna 12 - 14 December 2012

  21. Selection of events by centrality in TPC LAQGSM Minbias events, √s = 9 GeV XIV GDRE Workshop, Dubna 12 - 14 December 2012

  22. Selection of events by centrality in TPC LAQGSM Minbias events, √s = 9 GeV - 5 – 9 fm, semi-central events XIV GDRE Workshop, Dubna 12 - 14 December 2012

  23. Selection of centrality: Nparticipants GlauberMC Minbias events, √s = 9 GeV - 5 – 9 fm, semi-central events XIV GDRE Workshop, Dubna 12 - 14 December 2012

  24. Selection of events by centrality in ExtZDC LAQGSM Minbias events, √s = 9 GeV - 5 – 9 fm, semi-central events XIV GDRE Workshop, Dubna 12 - 14 December 2012

  25. Selection of events by centrality in ExtZDC LAQGSM Minbias events, √s = 9 GeV XIV GDRE Workshop, Dubna 12 - 14 December 2012

  26. Selection of events by centrality in ExtZDC LAQGSM Minbias events, √s = 9 GeV - 5 – 9 fm, semi-central events XIV GDRE Workshop, Dubna 12 - 14 December 2012

  27. RP reconstruction by Extended ZDC detector y ExtZDC x • No particle identification • Geant 4 , QGSP_BIC physics model • Systematic effect of magnetic field: • ~1o at 9 AGeV • increases to • ~3o at 3 AGeV XIV GDRE Workshop, Dubna 12 - 14 December 2012

  28. RP reconstruction by Extended ZDC detector Resolution δφRP and <cosδφRP> vs b M. Kapishin 2012 XIV GDRE Workshop, Dubna 12 - 14 December 2012

  29. Summary M. Kapishin 2012 • Extended ZDC detector (2.2<η<4.8) provides RP measurement at medium b (4<b<10 fm) with resolution of δφRP~22-35o in AuAu collisions at energies 5-9 AGeV, RP resolution deteriorates to δφRP~45-65o at 3 AGeV • Sensitivity of extended ZDC to RP azimuthal angle in central (b<3 fm) and peripheral collisions (b>12 fm) is much weaker • QGSM and UrQMD models give consistent results for RP resolution of extended ZDC, model dependence increases at low beam energies • ZDC cell size and length is not critical: dcell=10x10cm, L=60cm are sufficient for RP measurement. ZDC length is more crucial for energy flow measurement • Magnetic field systematics to φRP is ~1o at 9 AGeV which increases to ~3o at 3 AGeV. Reduced magnetic field at the lowest energy would decrease systematics XIV GDRE Workshop, Dubna 12 - 14 December 2012

  30. RP reconstruction by MC in Extended ZDC acceptance no particle identification protons + neutrons 7 GeV 7 GeV RP resolution, R = <cos(Δψ1)> Protons + neutrons +pions 7 GeV <Δψ1> = 33.8o R = 0.83 <Δψ1> = 34o R = 0.83 XIV GDRE Workshop, Dubna 12 - 14 December 2012

  31. Dependence of RP resolution on size of Extended ZDC Protons + neutrons XIV GDRE Workshop, Dubna 12 - 14 December 2012

  32. Dependence of RP resolution on size of Extended ZDC Protons + neutrons+pions XIV GDRE Workshop, Dubna 12 - 14 December 2012

  33. Plans for RP reconstruction: Include ExtZDC channel-by-channel Eloss in DST, Estimate the resolutions needed for the physical tasks. XIV GDRE Workshop, Dubna 12 - 14 December 2012

  34. Thank You! XIV GDRE Workshop, Dubna 12 - 14 December 2012

  35. Reaction plane resolution vs. numbers of particle and value of the flow XIV GDRE Workshop, Dubna 12 - 14 December 2012

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