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

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

3. 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 Evidence for deconfinement in A+A collisions NA45: excess in dilepton mass spectra Also wealth of RHIC data (jet quenching, constituent quark scaling for v2, B/M-ratio) NA50: anomalous J/  suppression In central A+A, thermal radiation V.I. Kolesnikov Round Table Discussion, 11 September 2009 3 Important to establish the onset of the observed signatures  motivation for next generation of HI experiments! for next generation of HI experiments!

4. 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  b range of the QCD phase diagram – new measurements will encourage theory to go further. Studying heavy ion collisions at NICA 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. Early stage conditions, partonic dynamics, energy and baryon transport Early stage conditions, partonic dynamics, energy and baryon transport net baryons, flow net baryons, flow Thermodynamic properties, test for equilibrium, (T-  B )-mapping Thermodynamic properties, test for equilibrium, (T-  B )-mapping inclusive hadron spectra, multiplicities and particle ratios inclusive hadron spectra, multiplicities and particle ratios EOS, transverse and longitudinal expansion, collective phenomena, EOS, transverse and longitudinal expansion, collective phenomena, space-time evolution space-time evolution spectra, HBT, cluster yields and coalescence spectra, HBT, cluster yields and coalescence Signals for phase transition Signals for phase transition strangeness-to-entropy (K/  ) ratio, slopes strangeness-to-entropy (K/  ) ratio, slopes Critical phenomena during nuclear matter evolution Critical phenomena during nuclear matter evolution particle ratio and net-baryon number fluctuations particle ratio and net-baryon number fluctuations Related topics (event characterization) centrality and event plane determination with hadron multiplicity Hadron probes For studying fundamental properties of the Hot QCD Matter (objectives/observables) (objectives/observables) 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 Homogenous acceptance (total  coverage) Event rate up to 7. 10 3 Hz Excellent PID capabilities 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 V.I. Kolesnikov Round Table Discussion, 11 September 2009 7

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

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

10. The MPD TOF detector Dimensions, coverage: length – 5 m inner radius - 1.2 m, outer radius - 1.4 m coverage - |  |<1.4 Granularity: 12 sectors in  55 RPC modules (62x7 cm 2 ) along z 48 2.5x3.5 cm 2 pads in each module # of readout channels – 31700 geom. efficiency - 95% thickness X/X 0 ~ 20% 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 ~ 10 3 cm -2 s -1 V.I. Kolesnikov Round Table Discussion, 11 September 2009 10 TOF barrel

11. TOF endcap(s) Dimensions, coverage: outer diameter - 2.5 m inner diameter - 0.4 m coverage 1.4<|  |<3 Granularity: 28 RPC modules (53,37,21x100,80,100 cm 2 ) 2640 4x4 cm 2 pads in total geometrical efficiency - 95% thickness – X/X 0 ~ 20% V.I. Kolesnikov Round Table Discussion, 11 September 2009 11 Final optimization of the TOF set-up is an ongoing task of MC studies

12. Double stack (10 gaps) RPC, read-out pads 2.5 х 3.5 cm 2 An RPC prototype active area 7 x 14 cm 2 TOF RPC prototyping V.I. Kolesnikov Round Table Discussion, 11 September 2009 12

13. 1 2 3 4 1 – MRPC, 2 – trigger scintillators, 3 – electronics, 4 - gas system. V.I. Kolesnikov Round Table Discussion, 11 September 2009 13 TOF RPC prototyping (2) Charge distribution for a 10 gaps RPC prototype. U= 11 kV. Gas mixture: 90% C 2 H 2 F 4 + 5% i-C 4 H 10 + 5% SF 6 ADC bins

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

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

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

17. MPD Simulation MPD Simulation & reconstruction MpdRoot (based on the FairRoot framework) V.I. Kolesnikov Round Table Discussion, 11 September 2009 17 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 and producing of inclusive spectra

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

19. TOF phase-space coverage V.I. Kolesnikov Round Table Discussion, 11 September 2009 19 Barrel Barrel + endcap 10 3 UrQMD (Au+Au) events Vertex_z = 0.0 cm Magnetic field = 0.5 T |  | < 1.4, p t =[0.1..2] GeVc – barrel |  | < 2.6, pt=[0.1..2] GeVc – barrel+endcap

20. Low-p t part of the acceptance is Low-p t part of the acceptance is of importance for spectra of pions of importance for spectra of pions Better coverage at low p t Better coverage at low p t for smaller B values for smaller B values B=0.2 T seems a better choice B=0.2 T seems a better choice for ‘yield & ratio’ measurements for ‘yield & ratio’ measurements Zoom at low-p t range Zoom at low-p t range (magnetic field optimization) (magnetic field optimization) 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 V.I. Kolesnikov Round Table Discussion, 11 September 2009 21 Efficiency ~ 90%

22. V.I. Kolesnikov Round Table Discussion, 11 September 2009 22 TOF PID capability m 2 =p 2 (c 2 T 2 /L 2 - 1) m 2 =p 2 (c 2 T 2 /L 2 - 1)  T=100 ps,  p/p,  L(p) – from MC track reconstruction. reconstruction. ~ 2   /K separation @ 1.3-1.5 GeV/c No vertex and IT reconstruction in the current analysis, zero capability for rejecting secondaries.. No secondaries – “ideal” conditions

23. PID method for hadron selection Simple contour cuts used Simple contour cuts used for selection: n  cut + max. for selection: n  cut + max. contamination 5% contamination 5% Parameters from mass 2 Parameters from mass 2 3 Gauss fits in momentum 3 Gauss fits in momentum bins bins Correction for losses/misID Correction for losses/misID from the fits from the fits V.I. Kolesnikov Round Table Discussion, 11 September 2009 23 Au+Au

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

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

26. Summary 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 Thank you for your attention!

31. L= 1·10 27 cm -2 s -1, 6.8 b for AuAu 6 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