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V.I. Kolesnikov on behalf of the MPD-TOF group

Study of charged hadron production in HI collisions with the MPD-TOF detector. V.I. Kolesnikov on behalf of the MPD-TOF group. Round Table Discussion JINR, Dubna 9-12 September 2009. Outline Physics motivation The apparatus and the MPD Time Of Flight detector

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V.I. Kolesnikov on behalf of the MPD-TOF group

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  1. Study of charged hadron production in HI collisions with the MPD-TOF detector V.I. Kolesnikov on behalf of the MPD-TOF group Round Table Discussion JINR, Dubna 9-12 September 2009

  2. Outline • Physics motivation • Theapparatus and the MPD Time Of Flight detector • Progress in TOF hardware development - RPC prototyping, tests • Particle Identification in the MPD experiment (TOF) • Identified hadron (p, K, p) pt-spectra in Au+Au collisions • Summary V.I. Kolesnikov Round Table Discussion, 11 September 2009 2

  3. Evidence for deconfinement in A+A collisions NA45:excess in dilepton mass spectra NA49: anomalies in hadron production: “Kink”– steeping in relative pion (entropy) production “Horn”– sharp maximum in the strangeness-to-entropy ratio in the transition region “Step”- plateau in the excitation function of the apparent temperature of hadrons NA50:anomalous J/y suppression In central A+A, thermal radiation Also wealth of RHIC data (jet quenching, constituent quark scaling for v2, B/M-ratio) Important to establish the onset of the observed signatures  motivation for next generation of HI experiments! V.I. Kolesnikov Round Table Discussion, 11 September 2009 3

  4. Studying heavy ion collisions at NICA • Comprehensive study of the phase diagram of strongly interacting matter: • Studying the phase boundary, nature of the transition and properties of the transition region • Search for the Critical End Point, signals of the Chiral Symmetry Restoration and P (CP) violation • Theoretically, little known about low T - high • mb range of the QCD phase diagram – new • measurements will encourage theory to go • further. • Requirements to experimental facility: • High luminosity  access to many rare probes • Large homogenous acceptance of the detector and.. • ..and good tracking and particle identification capability  total event reconstruction V.I. Kolesnikov Round Table Discussion, 11 September 2009 4

  5. Hadron probes For studying fundamental properties of the Hot QCD Matter (objectives/observables) • Early stage conditions, partonic dynamics, energy and baryon transport • net baryons, flow • Thermodynamic properties, test for equilibrium, (T-mB)-mapping • inclusive hadron spectra, multiplicities and particle ratios • EOS, transverse and longitudinal expansion, collective phenomena, • space-time evolution • spectra, HBT, cluster yields and coalescence • Signals for phase transition • strangeness-to-entropy (K/p) ratio, slopes • Critical phenomena during nuclear matter evolution • particle ratio and net-baryon number fluctuations • Related topics (event characterization) • centrality and event plane determination with hadron multiplicity V.I. Kolesnikov Round Table Discussion, 11 September 2009 5

  6. The Apparatus V.I. Kolesnikov Round Table Discussion, 11 September 2009 6

  7. MPD Detector Tracking TPC in a 0.5 T magnet + silicon vertex IT PID Charged: TOF (p<2.5 GeV/c) + dE/dx (p<0.5 GeV/c) Neutral: ECAL Event characterization & triggering Centrality: ZDC, BBS Timing: FD • Homogenous acceptance (total f coverage) • Event rate up to 7.103 Hz • Excellent PID capabilities V.I. Kolesnikov Round Table Discussion, 11 September 2009 7

  8. MPD Performance Acceptance (B=0.5 T): Full azimuthal IT (|h|<2.5) TPC (|h|<2) TOF (|h|<3) ECAL (|h|<1.2) BBC (1.5<|h|<4.2) Forward (2<|h|<4) ZDC (|h|>3) TPC (dE/dx): /K ~0.6 GeV/c, (,K)/p ~1.0 GeV/c TOF: p/K ~ 1.5 GeV/c (p,K)/p ~ 3 GeV/c V.I. Kolesnikov Round Table Discussion, 11 September 2009 8

  9. MPD TOF detector • design • RPC prototyping S. Golovatyuk V.I. Kolesnikov Round Table Discussion, 11 September 2009 9

  10. The MPD TOF detector Resistive Plate Chambers : • widely used (STAR, ALICE, HADES, CBM) • intrinsic time resolution up to 60 ps • functional in magnetic fields, 100% efficient up to fluxes ~ 103 cm-2s-1 Dimensions, coverage: length – 5 m inner radius - 1.2 m, outer radius - 1.4 m coverage - |h|<1.4 Granularity: 12 sectors in f 55 RPC modules (62x7 cm2) along z 48 2.5x3.5 cm2 pads in each module # of readout channels – 31700 geom. efficiency - 95% thickness X/X0 ~ 20% TOF barrel V.I. Kolesnikov Round Table Discussion, 11 September 2009 10

  11. TOF endcap(s) Dimensions, coverage: outer diameter - 2.5 m inner diameter - 0.4 m coverage 1.4<|h|<3 Granularity: 28 RPC modules (53,37,21x100,80,100 cm2) 2640 4x4 cm2 pads in total geometrical efficiency - 95% thickness – X/X0 ~ 20% Final optimization of the TOF set-up is an ongoing task of MC studies V.I. Kolesnikov Round Table Discussion, 11 September 2009 11

  12. TOF RPC prototyping Double stack (10 gaps) RPC, read-out pads 2.5 х 3.5 cm2 An RPC prototype active area 7 x 14 cm2 V.I. Kolesnikov Round Table Discussion, 11 September 2009 12

  13. TOF RPC prototyping (2) 4 1 3 2 1 – MRPC, 2 – trigger scintillators, 3 – electronics, 4 - gas system. Charge distribution for a 10 gaps RPC prototype. U= 11 kV. Gas mixture: 90% C2H2F4+5% i-C4H10 + 5% SF6 ADC bins V.I. Kolesnikov Round Table Discussion, 11 September 2009 13

  14. Particle identification & Hadron spectra V. Kolesnikov S. Lobastov V.I. Kolesnikov Round Table Discussion, 11 September 2009 14

  15. Hadron transverse spectra in A+A 40 AGeV NA49 • As many as possible hadron species • Apparent temperature (<pt>), transverse flow (T,b) using blast wave fits • Integrated distributions as an input for • statistical models (fits for (T-mB mapping)) Important! Precise measurement of the spectral shapes at low pt (pt<0.3 GeV/c) How well can we (MPD) reproduce shapes? • Focusing on K/p • Experimental uncertainties (NA49): 8-10% • Thermal models are advancing and • approaching the Horn • K/p - ratio to be measured with 5% precision • Feasible? 5 V.I. Kolesnikov Round Table Discussion, 11 September 2009 15

  16. K/p-ratio (data versus thermal model predictions) [A. Andronic et al., Phys. Lett. B 673 (2009) 142] V.I. Kolesnikov Round Table Discussion, 11 September 2009 16

  17. MPD Simulation & reconstruction MpdRoot(based on the FairRoot framework) Inside look at a HI collision MPD , Au+Au, 9 GeV • MC studies were carried out with the aim: • To test the simulation and reconstruction • To develop the methods and tools for hadron PID • and producing of inclusive spectra V.I. Kolesnikov Round Table Discussion, 11 September 2009 17

  18. MPD analysis chain Hadron spectra & yelds UrQMD 1.5k Au+Au, 9 GeV, 3-6 fm Transport GEANT Geometry, physics Track reconstruction Kalman filter No detailed simulation which includes all sub-detector characteristics TOF matching Particle ID, Hadron spectra Corrections: efficiency, decay, etc.. Track selection V.I. Kolesnikov Round Table Discussion, 11 September 2009 18

  19. TOF phase-space coverage Barrel • 103 UrQMD (Au+Au) events • Vertex_z = 0.0 cm • Magnetic field = 0.5 T • |h| < 1.4, pt=[0.1..2] GeVc – barrel • |h| < 2.6, pt=[0.1..2] GeVc – barrel+endcap Barrel + endcap V.I. Kolesnikov Round Table Discussion, 11 September 2009 19

  20. Zoom at low-pt range (magnetic field optimization) • Low-pt part of the acceptance is • of importance for spectra of pions • Better coverage at low pt • for smaller B values • B=0.2 T seems a better choice • for ‘yield & ratio’ measurements V.I. Kolesnikov Round Table Discussion, 11 September 2009 20

  21. TPC-TOF track matching • Reconstructed in TPC tracks propagated in the magnetic field to the TOF • Kalman filter method used to account for multiply scattering • Fast searching algorithm (STL-based) for the most probable pad crossing with the track extrapolation Efficiency ~ 90% V.I. Kolesnikov Round Table Discussion, 11 September 2009 21

  22. TOF PID capability m2=p2(c2T2/L2 - 1) DT=100 ps, Dp/p, DL(p) – from MC track reconstruction. No vertex and IT reconstruction in the current analysis, zero capability for rejecting secondaries .. No secondaries – “ideal” conditions ~ 2sp/K separation @ 1.3-1.5 GeV/c V.I. Kolesnikov Round Table Discussion, 11 September 2009 22

  23. PID method for hadron selection Au+Au • Simple contour cuts used • for selection: ns cut + max. • contamination 5% • Parameters from mass2 • 3 Gauss fits in momentum • bins • Correction for losses/misID • from the fits V.I. Kolesnikov Round Table Discussion, 11 September 2009 23

  24. Corrections Purity & contamination with the contour cut • Required corrections to raw yields (first version): • efficiency (TOF matching) • geometrical acceptance, decay • Particle ID • track reconstruction efficiency • feeddown from hyperon decays • syst. error estimates V.I. Kolesnikov Round Table Discussion, 11 September 2009 24

  25. Hadron spectra in Au+Au (MPD TOF, |y|<0.5, B=0.2 T) • First (prelim.) spectra look • reasonable • Low-pt efficiency problem • for K, p? • More detailed MC needed Lines: UrQMD input V.I. Kolesnikov Round Table Discussion, 11 September 2009 25

  26. Summary • Extensive preparation of the NICA Heavy Ion program shows that the MPD detector has excellent opportunities for making a comprehensive • exploration of the QCD phase diagram in the NICA energy range. • First studies on the performances of the MPD for measurement of • hadron production in Au+Au has been done. • The hadron spectra reconstruction in the current production chain • is feasible, but we have to understand better some thing concerning • low-pt efficiency corrections • Next steps: try to implement this analysis in more realistic environment • (vertex fiitting, IT reconstruction, dE/dx PID + all secondaries). • Ongoing activities enable further detector improvement and software • tools development. V.I. Kolesnikov Round Table Discussion, 11 September 2009 26

  27. 27 MPD Collaboration

  28. Thank you for your attention!

  29. L= 1·1027 cm-2 s-1 , 6.8 b for AuAu6 kHz minimum-bias rate (90%) • 300 Hz central (5%) A data set of 106 events is sufficient for spectra & yields analysis So, the statistical uncertainty is not a problem V.I. Kolesnikov Round Table Discussion, 11 September 2009 5

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