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12/24/2008

Azimuthal anisotropy measurement of neutral pion and direct photon in  s NN =200GeV Au+Au collisions at RHIC-PHENIX. Kentaro MIKI Univ. of Tsukuba mail to: kentaro@rcf2.rhic.bnl.gov. 12/24/2008. 0. Outlook. 1. Introduction / Physics Motivation. 2. Experiment.

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12/24/2008

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  1. Azimuthal anisotropy measurement of neutral pion and direct photon in sNN=200GeV Au+Au collisions at RHIC-PHENIX Kentaro MIKI Univ. of Tsukuba mail to: kentaro@rcf2.rhic.bnl.gov 12/24/2008

  2. 0. Outlook 1. Introduction/ Physics Motivation 2. Experiment 3. Data Reduction / Analysis 4. Results 5. Discussions 6. Conclusion / Summary Kentaro Miki

  3. 1-1. Quark Gluon Plasma How to study primordial state of matter? Quark Gluon Plasma -> QGP formed under extreme temperature and energy density. -> The quark and the gluon move freely in a finite volume. Heavy Ion Collision Experiment -> Relativistic heavy ion collisions provide a unique occasion to achieve those conditions on the earth. Critical temperature and energy density by Lattice QCD Tc ~ 170 MeV c ~ 1.2 GeV/fm3 Kentaro Miki

  4. 1-2. Heavy Ion Collision Experiment In order to provide the QGP state on the ground, the investigations have been taking place both at BNL and CERN, since 1980’s. Kentaro Miki

  5. 1-3. Electro Magnetic Probes Photons are the powerful probes to study the property of QGP since they do not interact strongly with any other particles and thus can carry out information on the states where they are emitted. Cartoon from Dinesh K. Srivastava, Quark Matter 2008 Photons are emitted from all stages. Kentaro Miki

  6. 1-4. Photon Sources Photons emitted from all stages of space -time evolution of heavy ion collisions. jet-fragmentation jet-conversion jet-Brems. Compton Annihilation Kentaro Miki

  7. 1-5. Direct Photon Spectra High pT direct photons are produced in the initial stage. Thermal radiation are emitted in the low pT region. thermal window -> 1~3 GeV/c prompt photon window -> 6~ GeV/c Blue line: Ncoll scaled p+p cross section High pT direct photons are well described by NLO-pQCD calculation and binary scaling. Phys. Rev., C69:014903(2004) Kentaro Miki

  8. 1-6. Nuclear Modification Factor High pT suppression of hadron yield in Au+Au collisions -> energy loss of hard scattered partons passing through the high density matter Non suppression of high pT direct photon -> they do not interact strongly with any other particles -> high pT photons are produced by initial parton collisions Nuclear Modification Factor The yield ratio of Au+Au and p+p normalized by the number of binary nucleon collisions. Kentaro Miki

  9. z y x 1-7. Azimuthal Anisotropy The participant region in non-central collision has spatial anisotropy. Pressure gradient is the largest in the shortest direction of the ellipsoid. Particle emission in momentum space reflects the initial spatial anisotropy. -Elliptic flow (v2) is defined by the 2nd coefficient of Fourier expansion Measured identified hadron v2 in low pT is well described by the hydro-dynamical prediction.  : azimuthal angle of particles  : azimuthal angle of reaction plane Kentaro Miki

  10. 1-8. Direct Photon v2 Photons v2 mechanisms Kentaro Miki

  11. 1-9. My Activities and Contributions BNL 2006.05.15 - 2006.07.13 2007.05.07 - 2007.07.07 2007.10.01 - 2007.12.22 2008.01.08 - 2008.01.27 (TOF-E calibration for Run4, Run5, Run6) (Centrality calibration for Run7) (TOF-E, Agel setup for Run7, Run8) JPS 2006.09.21 [pi0 v2 in Run4] 2007.03.27 [direct photon v2 in Run7] International Conference 2006.01 RHIC-AGS meeting (poster) 2006.11 QM2006 in Shanghai (poster) 2006.11 Workshop in Xi’an (oral) 2008.02 QM2008 in India (invited oral) Preliminary Request 2007.03 Preliminary for direct photon v2 in Run4 2008.01 Preliminary for pi0 v2 in Run7 Junior Research Associate working as JRA at RIKEN Riken accelerator progress report in 2007 Kentaro Miki

  12. 2-1. RHIC Accelerators Tandem Van de Graaff Linear Accelerator Booster Synchrotron Alternating Gradient Synchrotron Relativistic Heavy Ion Collider Experiments PHENIX, STAR, BRAHMS, PHOBOS Kentaro Miki

  13. 2-2. PHENIX Detectors Reaction Plane Detector 1.0 < || < 2.8 16 sectors in each side Beam-Beam counter event trigger reaction plane determination lead glass (PbGl) ・energy resolution 0.76  5.95 %/ E1/2 [GeV] lead scintillator (PbSc) ・energy resolution 2.1  8.1 %/ E1/2 [GeV] Kentaro Miki

  14. 3-1. Clustering Algorithm Isolated Cluster - 10 MeV threshold is applied - cluster formed with neighboring towers Local Maximum Tower - 80 MeV threshold - maximum amplitude in around 3x3 towers - “peak area towers” formed around 5x5 towers Split the Peak Area - divide the tower energy to each peak area by using parameterized shower profile Core Clustering - energy threshold (2% of energy sum in peak area) - Shower shape profile test (2 < 3.0) energy scale calibration by pi0 peak position width Kentaro Miki

  15. Inclusive photon Direct  hadron decay 3-2. Analysis Process 1. Inclusive photon v2 measurement 1-1. Photon identification 1-2. v2 extraction respected with reaction plane. 1-3. Hadron contamination study 2. pi0 v2 measurement 2-1. 0 identification 2-2. pi0 merging effect 2-3. v2 extraction 3. Hadron decay photon 3-1. Monte-Carlo simulation 4. Direct photon v2 calculation 0   ’ Kentaro Miki

  16. 3-3. Inclusive Photon (Raw) Spectra Data Set : Au+Au 200 GeV PHENIX Year-7 (~4.0G events) Event selection : minimum bias trigger (BBCNS > 2 ∩ ZDCNS > 1) BBC vertex < 30 cm Cluster cut : Ecore > 0.2 GeV Bad tower rejection Shower shape profile (2 < 3.0) Charged particle rejection Correction for invariant yield - Geometrical acceptance - Photon conversion - Energy scale - Remaining hadron Kentaro Miki

  17. 3-4. Inclusive photon v2 Fitting Function Kentaro Miki

  18. 3-5. Invariant Mass Distribution of 2 Basically, same cut with inclusive photon analysis. Combinatrial back ground is estimated by event mix distribution. Invariant mass distribution of 2 dN / d distribution of 0 Kentaro Miki

  19. 3-6. Systematical Uncertainty Kentaro Miki

  20. 3-7. Photons from Hadron Decays Since components other than 0 are not measured directly, the photons from hadrons other than 0 is estimated by using Monte-Carlo. Kentaro Miki

  21. 3-8. Hadron Decay Photon by Monte-Carlo above 3GeV, 0 77.6 %  19.0 %  3.7 %  0.5 % ’ 2.0 % Red point is measured data of 0 (PPG080). 0 output is normalized by data. other hadrons are normalized by 0 and their decay ratio. Cocktailed the decay photons v2 according to contamination ratio. Kentaro Miki

  22. 3-9. Direct photon v2 Double ratio Centrality 00 -92 % Direct photon v2 Centrality 00 -92 % Kentaro Miki

  23. 4-1. Inclusive Photon v2 Inclusive Photon v2 in Run7 by using RxNP - Measured 10% and 20% steps of centrality. - Extended up to 16.0 GeV/c Kentaro Miki

  24. 4-2. 0 v2 0 v2 is estimated by using RxNP in Run7 up to 16.0 [GeV/c]. - Measured 10% and 20% steps of centrality. - Extended up to 16.0 GeV/c Kentaro Miki

  25. 4-3. Hadron Decay Photon v2 Inclusive Photon v2 and Hadron Decay Photon v2 in Run7 by using RxNP - Significant different is appeared between Inclusive and hadron decay in high pT. - The systematic error on hadron decay is propagated from statistical and systematic error of 0. Kentaro Miki

  26. 4-4. Direct Photon v2 Direct Photon v2 in Run7 by using RxNP - extended up to 16GeV/c - run4 double ratio is used - Non-Zero v2 about 3GeV ? - Centrality dependence Kentaro Miki

  27. 5-1. Comparison with Identified Charged Hadrons The 0 v2 compared with identified charged hadron v2. - 0 v2 is good agreement with pion v2 (Run4) in low pT. - 0 v2 shows KET scaling as well in low pT. Kentaro Miki

  28. 5-2. Hadron v2 vs Photon v2 The 0 v2 compared with direct photon v2. - There is significant difference between hadron (0) and direct photon v2 Kentaro Miki

  29. 5-3. Eccentricity Dependence of High pT v2 High pT hadron v2 = Effect of jet suppression  path length ? Eccentricity v2 vs. Npart v2/ vs. Npart High pT v2 is scaled by eccentricity. Kentaro Miki

  30. 5-4. Low pT Direct Photon • = Dilepton method = •   *  e+e- , R H Dalitz 1951 Proc. Phys. Soc. A64 667-669 e- e+ Kentaro Miki

  31. 5-5. Direct Photon v2 via Dilepton R Centrality 00 -92 % - Improved below 3GeV/c - Ordinary method still better resolution above 4GeV/c Centrality 00 -92 % Kentaro Miki

  32. 5-6. Direct Photon at Low pT Low pT hadron v2 --> Hydro-dynamical flow Low pT photon v2 --> thermal radiation from QGP + Hadron gas thermal-Hadron gas v2 < hadron v2 thermal-QGP v2 < quark-scaled v2 ( KET = pT2-m02 - m0 ) Measured direct photon v2 is closer to hadron v2 than quark v2… Kentaro Miki

  33. 5-7. High pT Direct Photon High pT hadron v2 --> jet-fragment High pT photon v2 --> jet-fragment + prompt photon pQCD calculation in p+p Annihilation + Compton fragment Assumption prompt photon v2 = 0 jet-fragment v2 (photon) = jet-fragment v2 (hadron) = 0 v2 the ratio of prompt photons to initial partons is same between p+p and Au+Au Kentaro Miki

  34. 5-8. Prompt to Fragmentation Ratio High pT photon --> jet-fragment + prompt photon - v2 ratio is corresponding to the N ratio. Kentaro Miki

  35. 5-9. Prompt to Fragmentation Ratio Interpretation 1 0 v2 is not equal to jet-fragment v2 ?? if --- v2(0) < v2(photon from jet) --- > need the negative v2(prompt) or negative another v2 source. --- > jet-photon conversion ? Kentaro Miki

  36. 5-10. Prompt to Fragmentation Ratio Interpretation 2 fraction of jet-fragment and prompt is not corresponding between p+p and Au+Au ?? What is enhance source in Au+Au … ---> jet-photon conversion …? Kentaro Miki

  37. 6-1. Conclusion / Summary - Azimuthal anisotropy of Neutral pion, inclusive photon and direct photon are measured at Au+Au sNN = 200 GeV by using PHENIX Year-7 data set. - Extended pT range up to 16 GeV/c - Direct photon v2 have finite value above pT = 5GeV/c. -> Remaining the jet fragmentation photon contamination. - Eccentricity study -> There is different mechanism in high / low pT. - Low pT direct photon is estimated by dilepton analysis. -> direct photon v2 is similar to hadron v2 - Estimated the ratio of prompt and jet-fragmentation above pT = 5GeV/c -> jet-photon conversion effect might be seen. Kentaro Miki

  38. Ex Back up Kentaro Miki

  39. 3-10. Hadron decay photon v2 Hadron decay photon v2 is estimated by Exodus using mT scaled 0 v2. point-to-point fitting above 5 GeV mT scaled v2 for Exodus input Decay photon v2 from each parent particles. up/down line : sys. error from 0 statistical error Kentaro Miki

  40. 3-2. Reaction Plane Calibration Calibration for … 1. Response of BBC 2. Bias of beam line 3. Configuration of detectors <Reaction Plane Resolution> Kentaro Miki

  41. Ex. Production Process Direct photon production process in p+p collisions process1 (Annihilation + Compton Scattering) process2 (Fragmentation) parton distribution function (PDF) process1 process2 fragmentation function (PDF) Annihilation + Compton fragment Isolated direct photon cut : 0.1*E > Econe(R=0.5) Isolation cut can reduce the bremmstrahlung photons Kentaro Miki

  42. Ex. Comparison with Theoretical Prediction RxNP BBC arXiv:0712.0732v2 Kentaro Miki

  43. Ex. Comparison with RAA In the 2~4 GeV/c region, 1. Enhancement of direct photon in Au+Au 2. Direct photon v2 might be non-zero => There is other components ?? Kentaro Miki

  44. Ex. Additional Analysis How to improve the Direct photon v2 result in low pT region? > Direct photon v2 in Run7 still has large error bar… Estimation of thermal photon from virtual gamma analysis Kentaro Miki

  45. Ex. Thermal Photon v2 ?? - Improved below 3GeV/c - Ordinary method should be used above 4GeV/c RxNP RxNP BBC Kentaro Miki

  46. Ex. Thermal Photon v2 Comparison the final result with direct photon prediction. - Photon v2 is larger than theoretical curve. - Need to check the calculation model. - Need to check with the discussion of hadron analysis. Kentaro Miki

  47. 5-4. System Check of Eccentricity Scaling M. Shimomura, ATHIC 2008 v2 vs. Npart v2/ vs. Npart V2//Npart1/3 vs. Npart Low pT PHENIX PRELIMINARY High pT - There is different mechanism between low and high pT. Kentaro Miki

  48. Ex. Q=pT/sqrt(2) for prompt calculations, Turbide et al. (see also Arleo, JHEP 0609, 015 (2006), Liu & Werner, hep-ph/0712.3619 and Liu & Fries, nucl-th/0801.0453 . ). Kentaro Miki

  49. 5-8. Direct Photon Spectra via Dilepton Compare to NLO pQCD (p+p consistent with pQCD) Compare to thermal model D. d’Enterria, D. Peressounko (nucl-th/0503054)2+1 hydroT0ave=360 MeV (T0max=570 MeV)0=0.15 fm/c Data consistent with thermal + pQCD Kentaro Miki

  50. 6-2. Summary - Estimated inclusive / 0 / hadron decay photon v2 at 10% steps and 20% steps up to 60% and minimum bias. - direct photon v2 measured using RxNP or BBC. - estimated the low pT direct photon v2 by using the double ratio which is calculated in the thermal photon analysis. - Extended pT range up to 16 GeV/c - Improved v2 accuracy below 3 GeV/c Tasks… - Applying new energy calibration. - Systematic error study of remaining hadrons on the inclusive photon - Comparison with charged hadron data and several models. Kentaro Miki

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