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Azimuthal Anisotropy Measurement of Neutral Pion and Direct Photon in √sNN=200GeV Au+Au Collisions at RHIC-PHENIX

This article presents the measurement of azimuthal anisotropy of neutral pion and direct photon production in Au+Au collisions at RHIC-PHENIX. The study explores the properties of the Quark Gluon Plasma and the electro-magnetic particles emitted during these collisions. The data analysis and results are discussed in detail.

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Azimuthal Anisotropy Measurement of Neutral Pion and Direct Photon in √sNN=200GeV Au+Au Collisions at RHIC-PHENIX

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  1. Azimuthal anisotropy measurement of neutral pion and direct photon in sNN=200GeV Au+Au collisions at RHIC-PHENIX TAC seminar Kentaro MIKI Univ. of Tsukuba mail to: kentaro@rcf2.rhic.bnl.gov 11/25/2008

  2. 1. Introduction - Quark Gluon Plasma - Electro Magnetic Particle - Physic result at RHIC 1. Introduction 2. Physics Motivation 3. Experiment 4. Data Reduction 5. Data Analysis 6. Result / Discussion 7. Conclusion / Summary Kentaro Miki

  3. 1-1. Quark Gluon Plasma Is there an end in the size of the matter? Quark Gluon Plasma -> The quark and the gluon move freely in a large volume. -> QGP formed under high temperature and energy density. Heavy Ion Collision Experiment -> High temperature and high density necessary for generating QGP is produced by the high energy heavy ion collisions. Kentaro Miki

  4. 1-2. Heavy Ion Collision Experiment In order to provide the QGP state on the ground, Au nucleus is collided at sNN = 200 GeV by the Relativistic Heavy Ion Collider at BNL. Critical temperature / energy density by Lattice QCD Tc ~ 170 MeV c ~ 1.2 GeV/fm3 Kentaro Miki

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

  6. 1-4. 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

  7. All NLO-pQCD QGP-Thermal Jet-photon 1-5. Ratio of Photons 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 High pT direct photons are well described by NLO-pQCD calculation. Phys. Rev., C69:014903(2004) Kentaro Miki

  8. 1-6. High pT Direct Photon Yield NLO-pQCD calculation well described the photon data of p+p collisions in the world experiment. Blue line: Ncoll scaled p+p cross section High pT Photon yield in Au+Au is also well explained by NLO-pQCD. Kentaro Miki

  9. 1-7. Nuclear Modification Factor Non jet quench on the Direct photon Probe of isospin effect in high pT ? -> difference of quark charge between neutrons and photons -> yield of photons from p+p, p+n and n+n should have different value. -> The difference of photon yield from Au+Au and p+p would be appeared in RAA of direct photon. pT scaled by 62.4/200 (xT scaling inspired) Kentaro Miki

  10. 1-8. Direct Photon History Photons emitted from all stage in the history of hot dense medium. hard scatter How distinguish one photon from all emissions? pT (GeV) jet Brems. jet-thermal jet fragmentation sQGP hadron gas hadron decays log t 1 10 107 Cartoon from G. David, Hard Probe 2006 Kentaro Miki

  11. 2. Physics Motivation 1. Introduction 2. Physics Motivation - Azimuthal Anisotropy - Prediction of Photon v2 - My Activity 3. Experiment 4. Data Reduction 5. Data Analysis 6. Result / Discussion 7. Conclusion / Summary Kentaro Miki

  12. 2-1. Azimuthal Anisotropy The collision participation part in the early stage has spatial anisotropy. Pressure gradient is the largest in the shortest direction of the ellipsoid. Emitted particles reflect initial spatial anisotropy. -Elliptic flow (v2) is defined by the 2nd coefficient of Fourier expansion  : azimuthal angle of particles  : azimuthal angle of reaction plane Kentaro Miki

  13. 2-2. Emission Processes Photons are emitted from all stage of heavy ion collisions! sQGP Thermal Jet Fragmentation Hadron Decay Hard Scattered Jet Bremmstrahlung Kentaro Miki

  14. Photon emission from jet annihilation compton scattering v2 > 0 Bremsstrahlung (energy loss) v2 < 0 2-3. Prediction The sign of v2 depending on the production processes of photons. v2 = 0 Hard Scatter Jet Brems. v2 < 0 Jet Fragment v2 is a powerful tool to explore the source of direct photons. v2 > 0 QGP v2≥ 0 Turbide, Gale, arXiv:0712.0732 Kentaro Miki

  15. 2-4. My Activity 2006 01.08 RHIC-AGS meeting 09.21 JPA -fall- TOF calibration for Run6 BNL BNL 03.27 JPA -spring- 11.16-20 QM2006 in Shanghai preliminary request for direct photon v2 in Run4 11.24 International workshop in Xi’an 2007 04.01 Junior Research Associate preliminary request for pi0 v2 in Run7 BNL BNL Centrality calibration for Run7 11.01 start up RHIC Run8 2008 02.08 QM2008 in India BNL Kentaro Miki

  16. 3. Experiment 1. Introduction 2. Physics Motivation - Relativistic Heavy Ion Collider - the Pioneering High Energy Nuclear Interaction eXperiment 3. Experiment 4. Data Reduction 5. Data Analysis 6. Result / Discussion 7. Conclusion / Summary Kentaro Miki

  17. 3-1. RHIC Accelerators Tandem Van de Graaff Linear Accelerator Booster Synchrotron Alternating Gradient Synchrotron Relativistic Heavy Ion Collider Experiments PHENIX, STAR, BRAHMS, PHOBOS Kentaro Miki

  18. 3-2. 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

  19. 4. Data Reduction 1. Introduction 2. Physics Motivation 3. Experiment 4. Data Reduction - Photon Identify - Calibrations 5. Data Analysis 6. Result / Discussion 7. Conclusion / Summary Kentaro Miki

  20. 4-1. Photon Identify 1. Cluster 2. Peak area 3. EMCal shower Kentaro Miki

  21. 4-2. Calibration ~Centrality~ The centrality is determined by the correlation of BBC charge sum and ZDC energy in PHENIX. The boundaries of centralities are calibrated to make flat the centrality distribution. <BBC charge sum method in Run7> <Clock method in Run4> Kentaro Miki

  22. 4-3. Calibration ~Reaction Plane~ <Reaction Plane Resolution> Kentaro Miki

  23. 5. Data Analysis 1. Introduction 2. Physics Motivation 3. Experiment 4. Data Reduction 5. Data Analysis - Inclusive Photon - 0 - Hadron Decay by Simulation - Direct Photon 6. Result / Discussion 7. Conclusion / Summary Kentaro Miki

  24. Inclusive photon Direct  hadron decay 5-1. Data analysis 0   ’ 2nd harmonic amplitude : v2 Kentaro Miki

  25. 5-2. Inclusive photon Centrality : 0-92% (10% step) pT range : 1.0 - 16.0 [GeV/c] Data Set : Au+Au 200 GeV Run4 (~800M events) Run7 (~4.0G events) Event / Cluster cut : BBC vertex < 30 cm ZDCNS > 1 Centrality defined by BBC only Reaction plane defined by RxNP emc Cluster energy > 0.2 GeV pc3 rejection cut > 6.5 cm Kentaro Miki

  26. 5-3. Inclusive photon v2 (Run7) Fitting Function Kentaro Miki

  27. 5-4. Invariant mass distribution of 0 Basically, same cut with inclusive photon analysis. Combinatrial back ground is estimated by event mix distribution. Invariant mass distribution of 2 dN / dphi distribution of pi0 Kentaro Miki

  28. 5-5. 0 raw yield Au+Au 200 GeV Filled circle : 0 raw yield Opened circle : 0 yield at Run4 PHENIX preliminary Kentaro Miki

  29. 5-6. Hadron decay contamination Since components other than 0 cannot be measure directly, the hadron decay contamination is estimated by using Monte-Carlo. Kentaro Miki

  30. 5-7. 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

  31. 5-8. Cocktail above 3GeV, 0 77.6 %  19.0 %  3.7 %  0.5 % ’ 2.0 % Parent spectra from Exodus output. 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

  32. 5-9. Direct photon v2 Kentaro Miki

  33. 6. Result / Discussion 1. Introduction 2. Physics Motivation 3. Experiment 4. Data Reduction 5. Data Analysis 6. Result / Discussion 7. Conclusion / Summary Kentaro Miki

  34. 6-1. Run4 Result Inclusive / Hadron Decay / Direct photon v2 in Run4 200GeV Au+Au - Photon v2 is measured up to 10GeV/c. - Consistent with zero. Kentaro Miki

  35. 6-2. Run7 Inclusive Photon Inclusive Photon v2 in Run7 by using RxNP - Measured 10% and 20% steps of centrality. - Extended up to 16.0 GeV/c Kentaro Miki

  36. 6-3. Run7 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

  37. 6-4. Comparison with Hadrons The 0 v2 compared with charged hadron v2. - 0 v2 is good agreement with pion v2 (Run4). - There is un-consistency between the result from RxNP and BBC above 4GeV/c. Kentaro Miki

  38. 6-5. 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

  39. 6-6. 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 Bremsstrahlung (energy loss) annihilation compton scattering v2 > 0 v2 < 0 Kentaro Miki

  40. 6-7. Comparison with the result by BBC. Reaction Plane angle is defined by RxNP Reaction Plane angle is defined by BBC  Central Arm || < 0.35 BBC 3.0 < |eta| < 3.9 RxNP 1.0 < |eta| < 2.8 Kentaro Miki

  41. 6-8. Comparison with Theoretical Prediction RxNP BBC arXiv:0712.0732v2 Kentaro Miki

  42. 6-9. 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

  43. 6-10. 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

  44. 0-30 90-140 200-300 140-200 Rdata ÷ ÷ ÷ 6-11. Virtual Photon Analysis Kroll-Wada Formula Kentaro Miki

  45. 6-12. Thermal Photon Spectra (inclusive) = (decay) + (direct) Double ratio: (incl/0)measured / (decay/ 0)background = incl/ decay =1+ direct/ decay 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

  46. 6-13. Thermal Photon v2 ?? - Improved below 3GeV/c - Ordinary method should be used above 4GeV/c RxNP RxNP BBC Kentaro Miki

  47. 6-14. 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

  48. 7-1. Conclusion - 0 and inclusive photon v2 is very effective probe to study the high pT region. - Direct photon seems to have non-zero v2 above 3GeV/c. - The influence of jet (or jet-suppression) is appeared even direct photon. - Virtual photon analysis is effective in low pT region. - Thermal photon v2 is larger than theoretical prediction curve described in arXiv:0712.0732v2. - Need to more physics study with charged hadron analysis or several models. Kentaro Miki

  49. 7-2. 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

  50. Ex Back up Kentaro Miki

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