K. Ozawa (University of Tokyo)

University of Tokyo, Tsukuba University,

Hiroshima University, KEK, Waseda

University, Nagasaki Institute of Applied

Science

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.

2010/04/26US/J meeting2

Observe Quark-Gluon-Plasma

2010/04/26US/J meeting3

Study of quarkdeconfinement

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.

Create high temperature matter.

2010/04/26US/J meeting4

High Energy Heavy Ion collisions at RHIC.

Au-Au @ sNN = 200 GeV

Measure matter properties

RHIC

PHENIXInitial Energy Density / TemperatureThermalization and thermal parametersQuark Degree-of-Freedom of the matter Quark de-confinementOrder parameter of the chiral symmetry

Construction• Done by 2004

Operation• Costs• Man Power

Calibration• Electron

Identification• Time of Flight• Trigger &

Luminosity• Reaction Plane

Physics Analysis• ~ 3 Dr thesis per

year2010/04/26US/J meeting5

AGEL RXPD

TOFRICHBBC

Magnet

coils

Japanese Detectors in PHENIX

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/ suppression

Further physics results can be obtained with Run 10 data.

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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 b-1 1.5 G 270 TB

Run-7 2007 Au-Au 200 813 b-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 b-1 8.2 G 1.0 PB

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)

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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

2010/04/26US/J meeting9

A+A

ddpNdT

ddpNdpR

TNN

AA

TAA

TAA /

/)(

2

2

dNg/dy = 1000（ 30 ～ 50 x Nucleus ）dNg/dy = 1000（ 30 ～ 50 x Nucleus ）

2010/04/26US/J meeting10

Angle correlation caused by Jet

Correlation is disappeared in Au+Au

○proton●Au+Au

Big step between SPS and RHIC

Angle correlationCollision Energy

Dep.

Particle species Dep.

Particles are not interactedConserve initial isotropy

Medium is formed & Thermalized Geometry creates

anisotropy

Measurements of anisotropic particle emission

Large anisotropy

Early Thermalize

Anisotropic flow of 7Li atom gas

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US/J meeting

Quark number scaling

Measurement of Melting T

TJ/ = 2.0Tc

J/Melting

Color ScreeningAnisotropy is scaled by the number of constituent quark in meson and baryon

KET: Kinetic Transverse Energy (ET – M0)Mass difference is corrected

meson follows other mesons.Note: M ~ Mp

Color Screening

cc

If Rforce ~ Rscreening < Rbind, qq is never bound.Only with de-confinement

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Hydro + J/T. Gunji et al. PRC 76:051901,2007

QGP

Enough Initial Energy and TemperatureHigh gluon density matter is formedThermalization is achievedDirect evidence of de-confinement

Evidences for creation of Quark Gluon Plasma

Suggests

s

4Predicted limit

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US/J meeting

Measurements of /s

Relation with AdS/CFT

Based on flow and charm measurements

Press Release in Japan

2010/04/26 14US/J meeting

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J

Correlated

DD

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De-confinement (J/ suppression)

Charm, bottom quark in QGP

Chiral symmetry via

Thermal photon via lepton pair

PLB670, 310(2009)

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p+p NORMALIZED TO mee<100 MeV

Clear enhancement is observed in the Clear enhancement is observed in the mass region below mass region below ..

arXiv:0706.3034

2010/04/26

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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

No model can reproduce experimental data at this moment.

No model can reproduce experimental data at this moment.

arXiv:0706.3034

Both statistical and systematic errors depend on huge background caused by Dalitz decays and conversions

Both statistical and systematic errors depend on huge background caused by Dalitz decays and conversions

US/J meeting18

• One gas volume

– Same gas for Radiator and detection

– CF4 (γ ｔｈ ~ 28)

• Window less Cerenkov conter

• CsI photo casode

– UV sensitive (6 eV, 200nm)

signal electron

Cherenkov blobs

partner positronneeded for rejection

e+

e-

pair openingangle

~ 1 m

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~20 pe

few pe

Hadron

Single electron

Projected Performance @ Run10

Rejection factor

Np.e. of single electron

Luminosity [unit of Run4 ]

1.4 /nb recordedimproves effective statistics by ≥ 35

Signal significance

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• 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

Direct Photon arXiv:0804.4168

To be published in PRL

2010/04/26US/J meeting21

We have a press release at APS spring meeting.

Our experiment is introduced as a hottest science experiment on the planet!

Our experiment is introduced as a hottest science experiment on the planet!

We need to explore QCD nature

RHIC can explore the region below using collision energy scan.

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US/J meeting

QCD Phase Transition In QCD phase diagram, critical point is important, since the point can determine the absolute scale.

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.

2010/04/2623

US/J meeting

2010/04/26 24US/J meeting

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

2010/04/26US/J meeting25

R. Rapp (Nucl. Phys A661(1999) 238c

Au+Au

e+ e -

e+ e -

Background Rejection with new detector

Installed in 2009 Fully operated in 2010 run

Also, long data acquisition is expected in 2010

US/J meeting26

Direct photonDirect photon• Directly emitted from Directly emitted from

the medium the medium Not from hadronNot from hadron

• Hard photonHard photon Initial pQCDInitial pQCD

• Thermal photonThermal photon Hadron gasHadron gas QGPQGP

Turbide, Rapp, Gale, Phys. Rev. C 69 (014903), 2004

Window for thermal photons from QGP in this calculation: Window for thermal photons from QGP in this calculation: ppTT = 1 - 3 GeV/ = 1 - 3 GeV/cc

pQCD calculation should be confirmed in High ppQCD calculation should be confirmed in High pTT region region

After subtraction of large After subtraction of large background from hadron background from hadron decays, decays,

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