Status of PHENIX Experiment K. Ozawa (University of Tokyo) University of Tokyo, Tsukuba University, Hiroshima University, KEK, Waseda University, Nagasaki Institute of Applied Science

Current status The project is associated with study of hot and dense nuclear matter generated by high energy heavy ion collisions. Relativistic Heavy Ion Collider (RHIC) and PHENIX detector system are constructed at Brookhaven National Laboratory (BNL). Japan-US collaboration works effectively in every steps of the experiment. Huge number of events are acquired in recent 10 years and many measurements suggest formation of Quark-Gluon-Plasma. US/J meeting 2010/04/26

Observe Quark-Gluon-Plasma It can be reproduced and studied by RHIC. Physics motivation Observe Quark-Gluon-Plasma Study of quark deconfinement Phase transition of “QCD vacuum” In ordinary matter, quarks are confined. QGP is a quark de-confined state. It can be reproduced and studied by RHIC. US/J meeting 2010/04/26

Experimental Method Create high temperature matter. RHIC High Energy Heavy Ion collisions at RHIC. Au-Au @ sNN = 200 GeV Measure matter properties PHENIX Initial Energy Density / Temperature Thermalization and thermal parameters Quark Degree-of-Freedom of the matter Quark de-confinement Order parameter of the chiral symmetry US/J meeting 2010/04/26

PHENIX: Japanese Contribution AGEL RXPD TOF RICH BBC Magnet coils Construction Done by 2004 Operation Costs Man Power Calibration Electron Identification Time of Flight Trigger & Luminosity Reaction Plane Physics Analysis ~ 3 Dr thesis per year Japanese Detectors in PHENIX US/J meeting 2010/04/26

History PHENIX Year Species s1/2 [GeV ] Ldt Ntot (sampled) Data Size Run3 2002/03 d-Au 200 2.74 nb-1 5.5 G 46 TB Run4 2003/04 Au-Au 200 　 241 mb-1 1.5 G 270 TB Run-7 2007 Au-Au 200 813 mb-1 5.1 G 650 TB Run-8 2008 d-Au 200 80 nb-1 160G 3.8 PB Run-10 2010 Au-Au 200 1300 mb-1 8.2 G 1.0 PB Since June 2000, whole PHENIX detectors including Japanese detectors are well operated and huge statistics are obtained With Run4 and run7 integrated luminosity, several measurements are achieved. v2 of identified particles, Jet energy loss, J/y suppression Further physics results can be obtained with Run 10 data. US/J meeting 2010/04/26

Publication status 88 papers published to date 8 papers are submitted citations extremely impressive 4 250+ top cite paper 20 100+ top cite paper + 28 50+ top cite paper PHENIX White paper (Nucl.Phys. A757,184, 2005) 2nd most cited nucl-ex paper in 2007 Total 829 citations Most cited paper, with 503 citations is “Suppression of hadrons with large transverse momentum in central Au+Au collisions at s(NN)**(1/2) = 130-GeV” Adcox, et al., PRL 88, 022301 (2002) (Dr thesis, K. Oyama, University of Tokyo) US/J meeting 2010/04/26

Physics results US/J meeting 2010/04/26

High density Matter p+p A+A Measuring high pT particle yields: Initial yields and pT distributions can be predicted from p+p measurements + pQCD + cold nuclear effects Deviations can be attributed to the medium formed in A+A collisions p+p A+A dNg/dy = 1000 （30～50 x Nucleus） US/J meeting 2010/04/26

Jet tomography: Updated Angle correlation Collision Energy Dep. p+p Big step between SPS and RHIC Angle correlation caused by Jet Correlation is disappeared in Au+Au Particle species Dep. ○proton ●Au+Au US/J meeting 2010/04/26

Measurements of anisotropic particle emission Thermalization Measurements of anisotropic particle emission Anisotropic flow of 7Li atom gas Particles are not interacted Conserve initial isotropy Medium is formed & Thermalized Geometry creates anisotropy Large anisotropy Early Thermalize US/J meeting 2010/04/26

Deconfinement Quark number scaling J/y Melting Anisotropy is scaled by the number of constituent quark in meson and baryon Color Screening If Rforce ~ Rscreening < Rbind, qq is never bound. Only with de-confinement Measurement of Melting T Hydro + J/y T. Gunji et al. PRC 76:051901,2007 KET: Kinetic Transverse Energy (ET – M0) Mass difference is corrected TJ/y = 2.0Tc f meson follows other mesons. Note: Mf ~ Mp US/J meeting 2010/04/26

Evidences for creation of Quark Gluon Plasma Perfect Fluid Evidences for creation of Quark Gluon Plasma Enough Initial Energy and Temperature High gluon density matter is formed Thermalization is achieved Direct evidence of de-confinement Suggests QGP Measurements of h/s Press Release in Japan Based on flow and charm measurements Relation with AdS/CFT Predicted limit US/J meeting 2010/04/26

Updates in the last year US/J meeting 2010/04/26

Electron pair measuremnts De-confinement (J/y suppression) Charm, bottom quark in QGP Chiral symmetry via f, w Thermal photon via lepton pair p0 w f J/y Correlated DD PLB670, 310(2009) US/J meeting 2010/04/26

Final e+e- spectrum in Run4 arXiv:0706.3034 p+p NORMALIZED TO mee<100 MeV Clear enhancement is observed in the mass region below w. US/J meeting 2010/04/26

Model comparison Several models arXiv:0706.3034 Black Line No model can reproduce experimental data at this moment. Black Line Baseline calculations Colored lines Several models Low mass M>0.4GeV/c2: some calculations OK M<0.4GeV/c2: not reproduced Mass modification Thermal Radiation Both statistical and systematic errors depend on huge background caused by Dalitz decays and g conversions US/J meeting 2010/04/26

Dalitz Rejecter around vertex signal electron Cherenkov blobs partner positron needed for rejection e+ e- qpair opening angle ~ 1 m Window less Cerenkov conter One gas volume Same gas for Radiator and detection CF4 (γｔｈ　~　28) CsI photo casode UV sensitive (6 eV, 200nm) US/J meeting 2010/04/26

Performance in Run9 Hadron Rejection factor Projected Performance @ Run10 few pe Np.e. of single electron Single electron Signal significance 1.4 /nb recorded improves effective statistics by ≥ 35 ~20 pe Luminosity [unit of Run4 ] US/J meeting 2010/04/26

Thermal photon Direct Photon arXiv:0804.4168 p+p (Run5) result with * method agrees with NLO pQCD predictions, and with statistical method at high pT Confirmation of the method For Au+Au (Run4), there is a significant low pT excess above p+p expectations Interpreted as thermal emission -> Initial T US/J meeting To be published in PRL 2010/04/26

Hottest experiment! We have a press release at APS spring meeting. Our experiment is introduced as a hottest science experiment on the planet! US/J meeting 2010/04/26

We need to explore QCD nature Future Prospects We need to explore QCD nature QCD Phase Transition In QCD phase diagram, critical point is important, since the point can determine the absolute scale. RHIC can explore the region below using collision energy scan. Need Luminosity US/J meeting 2010/04/26

Summary The project is associated with study of hot and dense nuclear matter to observe Quark-Gluon-Plasma and investigate its properties. For this purpose, Relativistic Heavy Ion Collider (RHIC) and PHENIX detector system are constructed at Brookhaven National Laboratory (BNL). Huge number of events are acquired in recent 10 years and many measurements suggest generation of Quark-Gluon-Plasma. US/J meeting 2010/04/26

Back ups US/J meeting 2010/04/26

Chiral symmetry in hadronic matter As a signal of chiral symmetry restoration Measure vector mesons. Mass shift or modification is expected. Lepton decays become good probes. Not interacting “strongly.” Current results has poor statistics due to large background R. Rapp (Nucl. Phys A661(1999) 238c Au+Au Background Rejection with new detector  e+ e - po   e+ e - Installed in 2009 Fully operated in 2010 run Also, long data acquisition is expected in 2010 US/J meeting 2010/04/26

Turbide, Rapp, Gale, Phys. Rev. C 69 (014903), 2004 Thermal photon Turbide, Rapp, Gale, Phys. Rev. C 69 (014903), 2004 Direct photon Directly emitted from the medium Not from hadron Hard photon Initial pQCD Thermal photon Hadron gas QGP After subtraction of large background from hadron decays, Window for thermal photons from QGP in this calculation: pT = 1 - 3 GeV/c pQCD calculation should be confirmed in High pT region 2010/04/26 US/J meeting