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Results from STAR and status of the FTPC

Results from STAR and status of the FTPC. María J. Mora Corral. Project Review 2002 MPI. Forward TPC group. Permanent Physicists V. Eckardt, P. Seyboth Computing J. Seyboth, M. Vidal Postdocs M. Oldenburg (1/2003), M.J. Mora Corral Ph.D. Students J. Putschke, F. Simon Diploma Student

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Results from STAR and status of the FTPC

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  1. Results from STARand status of the FTPC María J. Mora Corral Project Review 2002 MPI

  2. Forward TPC group • Permanent Physicists • V. Eckardt, P. Seyboth • Computing • J. Seyboth, M. Vidal • Postdocs • M. Oldenburg (1/2003), M.J. Mora Corral • Ph.D. Students • J. Putschke, F. Simon • Diploma Student • P. Maierbeck Lots of help from MPI technical and computing support Project Review MPI München, 16/Dec/2002

  3. Outline • Heavy ion collisions at RHIC • The STAR experiment • Highlights from STAR • Particle ratios • Anisotropic flow • Suppression at high pT • Forward TPC from MPI-München • Summary and outlook Project Review MPI München, 16/Dec/2002

  4. How does matter look at high density and temperature? High Density QCD Matter in Laboratory • Determine its properties QCD Prediction: Phase Transitions • Deconfinement to QGP • Chiral symmetry restoration Relevance to other research areas? • Quark-hadron phase transition in early Universe • Cores of dense stars • High density QCD Project Review MPI München, 16/Dec/2002

  5. BRAHMS PHOBOS RHIC PHENIX STAR Ions: A = 1 ~ 200, pp, pA, AA, AB The Relativistic Heavy Ion Collider two superconducting rings 3.83 km in circumference Design PerformanceAu + Aup + p Max snn 200 GeV 500 GeV L [cm-2 s -1 ] 2 x 10261.4 x 1031 Interaction rates 1.4 x 103 s -1 6 x 105 s -1 Project Review MPI München, 16/Dec/2002

  6. Silicon Vertex Tracker + Silicon Strip Detector EMCalBarrel+ End Cap EMC Photon Multiplicity Detector Forward Time Projection Chamber 2nd year detectors(2001-2002) Au+Au and p+p @ 200 AGeV 3rd year detectors(2003) d+Au and p+p @ 200 AGeV The STAR experiment STAR uses the world’s largest Time Projection Chamber Trigger Barrel+ Time of Flight Patch Ring Imaging Cerenkov Zero Degree Calorimeter 1st year detectors (2000) Au+Au @ 130 AGeV Project Review MPI München, 16/Dec/2002

  7. a STAR event … One of the first Au+Au events at CM energy of 200 AGeV • Efficient tracking and momentum measurement • Particle identification: dE/dxinvariant masstopological • p, p-bar, p+, p-, K+, K- , L, L-bar, W, W-bar, X, X-bar… Project Review MPI München, 16/Dec/2002

  8. _ _ _ _ _ _ STAR preliminary p-bar/p ratios • Pair-production increases with collision energy. • Mid-rapidity region is not yet baryon-free! • Pair-production is larger than baryon transport. • 80% of protons from pair production. Early Universe p-bar/p ratio      Project Review MPI München, 16/Dec/2002

  9. Particle ratios • STAR excels in particle yields study! (and good agreement between different experiments ). • Evidence for thermal equilibrium at high temperature and density. • RHIC increasing s: same temperature, decreasing baryon density. Project Review MPI München, 16/Dec/2002

  10. lab-plane Interactions STAR Preliminary 130GeV Final state azimuthal momentum asymmetry Anisotropic flow Azimuthal anisotropy (flow) Non-central collisions: spatially asymmetric initial state Fourier analysis  1+2v1cos(lab-plane)+2v2cos2(lab-plane)+… Project Review MPI München, 16/Dec/2002

  11. STAR Preliminary 130GeV Elliptic flow PRL 86, 402 (2001) & nucl-ex/0107003 • At moderate pT the elliptic flow is well described by hydro models, even for different particles. • At high pT the trend can be reproduced including hard scattering with an energy loss. Project Review MPI München, 16/Dec/2002

  12. schematic view of jet production hadrons leading particle q q hadrons leading particle Vacuum QGP High pT particles and suppression • Jets and mini-jets at s = 200GeV • 30-50 % of particle production • High pt leading particles • Azimuthal back-to-back correlations • Extend into perturbative regime • Calculations reliable (?) • Scattered partons propagate through matter & radiate energy (dE/dx ~ x) in colored medium • Interaction of parton with partonic matter • Suppression of high pt particles: “jet quenching” • Suppression of back-to-back correlations • Creation of event-plane correlations Project Review MPI München, 16/Dec/2002

  13. Preliminary High pT particle suppression • Scale Au-Au data by the number of binary collisions • Compare to UA1pp reference data measured at 200 GeV Evidence for hadron suppression at high pt Partonic interaction with matter? dE/dx? Project Review MPI München, 16/Dec/2002

  14. The forward TPC signal readout Bfield • 2 FTPCs with 1.20 m length. • Rinner = 7.73 cm, Router = 30.05cm. • Covering || region 2.5-4.0. • 10 padrows in the beam direction with 6 azimuthal sectors each. • Efieldradial, 240-1400V/cm,  beam. • B field =0.5 T, || beam. • Gas mixture 50%Ar 50%CO2. Efield • Extend STAR charged particle acceptance into region 2.5 < || < 4.0. • Study charged particle and net proton (h+-h-) spectra. • Anisotropic flow. • Ks0 and L production. • Fluctuations of <pT>. • DCC search. Project Review MPI München, 16/Dec/2002

  15. COMPLICATIONS: Drift velocity not constant. Drift path curved due to ExB deflection. vD(r) and D(r) need to be known with high accuracy We use MAGBOLTZ calculations Very sensitive to calibration The forward TPC: What is new? PROBLEM: Region with high particle multiplicity  achieve high two track separation SOLUTION:Apply a radial electric field ( magnetic field) Project Review MPI München, 16/Dec/2002

  16. Cluster finder + Cluster unfolding Laser tracks+ Drift Vel. Monitor Hits (pad, time) Magboltz drift maps Space points (r,j) Track finder Vertex extrapolation Track (space point collection from same particle) From signals to tracks Charge signals (pad, time) Project Review MPI München, 16/Dec/2002

  17. Radius step (cm) Sector number Charge-step (maximum drift time of the electrons) shows a hardware sector wise structure  azimuthal dependence cluster position! 200mm shift Sensitive to small (200 mm) inaccuracy in detector geometry which leads to 2mm fluctuation!! Example: Charge step sensitivity Drift time Project Review MPI München, 16/Dec/2002

  18. TPC multiplicity CTB multiplicity FTPC multiplicity FTPC multiplicity FTPC raw multiplicity vs TPC,CTB no quality cuts applied on FTPC tracks (primaries & secondaries) Good correlation between FTPC and TPC, CTB multiplicity. Project Review MPI München, 16/Dec/2002

  19. 1/Nevent*dN/dpt 1/Nevent*dN/d  pt [GeV] Raw charged particle spectra pT distribution h distribution Efficiency and acceptance calculations have started to extract corrected charged particle spectra ! Project Review MPI München, 16/Dec/2002

  20. first harmonic second harmonic V1= V2= FTPC event plane correlations FTPCEast/FTPCWest FTPCEast/FTPCWest • Elliptic flow (v2) visible in the FTPCs • Directed flow (v1) signal is very small v2 FTPCt/TPC Project Review MPI München, 16/Dec/2002

  21. FTPC elliptic flow • Not final results • Elliptic flow decreases with pseudorapidity? Project Review MPI München, 16/Dec/2002

  22. Summary and outlook • Exciting new results from STAR year II • Net baryons have continued to decrease with increasing energy, although there’s still some stopping/baryon transport to ycm. • Hadronic particle yields reveal a statistical behaviour. • Suppression of particles and azimuthal correlations at high pT indicate parton energy loss in the medium. • First year with the FTPC • 90K minBias, 1.6M central Au+Au events and 15M p+p events collected. • Radial drift and ExB effects make calibrations challenging. • Spectra and anisotropic flow studies in progress. • Plans for next Run (January-May 2003) • 10 weeks d+Au and 3 weeks polarized p+p collisions. • Improved laser and DV calibrations. • Continuation of data taking in 2003-2004 Project Review MPI München, 16/Dec/2002

  23. Efficiencies • First approach to efficiencies with simulations. • For final efficiencies we need to embed a simulated particle into real event. Project Review MPI München, 16/Dec/2002

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