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

2. 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

3. 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

4. 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

5. 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

6. History
PHENIX Year Species s1/2 [GeV ] Ldt Ntot (sampled) Data Size
Run / d-Au nb G TB
Run / Au-Au 　 mb G TB
Run Au-Au mb G TB
Run d-Au nb G PB
Run Au-Au mb G 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

7. Publication status 88 papers published to date 8 papers are submitted
citations extremely impressive
top cite paper
top cite paper
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, (2002)
(Dr thesis, K. Oyama, University of Tokyo)
US/J meeting
2010/04/26

8. Physics results
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2010/04/26

9. 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

10. 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

11. 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

12. 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

13. 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

14. Updates in the last year
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2010/04/26

15. 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

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

17. 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

18. 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

19. Performance in Run9 Hadron Rejection factor
Projected 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

20. Thermal photon
Direct Photon
arXiv:
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

21. 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

22. 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

23. 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

24. Back ups
US/J meeting
2010/04/26

25. 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

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 = GeV/c
pQCD calculation should be confirmed in High pT region
2010/04/26
US/J meeting