The aerogel detector for PHENIX experiment was constructed with Dubna Group participation on all stage of this project.

Purpose:

Obtain additional information about Jet Quenching effect

RRelativistic elativistic HHeavy eavy IIon on CCollider (ollider (RHICRHIC))

PPioneering ioneering HHigh igh EEnergy nergy NNuclear uclear IInteraction enteraction eXXperiment (periment (PHENIXPHENIX))

ID-hadrons, Muons, Electrons, Photons

High Rate Capability. Rare Processes.

Aerogel Cherenkov Detector• Modules for half sector are installed in 2003• Enhancement of PID capability at PHENIX

– Proton separation from /K up to p = 7 GeV/c

chargedtrack

160 segments

z (beam

) dire

ction

Azim

uthal angle

Half of th

em in

2003

Reflector (Goretex) PMT

(3 inch)

Aerogel (index~1.011) （ 11x22x20

cm3 ）

Integration Cube (Air)PMT(3 inch)

JET Quenching

Modification of Jet property in AA collisions because partons propagating in colored matter lose energy.

One of the possible observableTp

Was predicted in a lot of works. Some of them (not all) are:

1

0)(Pd

J.D.Bjorken (1982), Fermilab – PUB – 82 – 059 - THY.M.Gyulassy and M.Palmer, Phys.Lett.,B243,432,1990.X.-N.Wang, M.Gyulassy and M.Palmer, Phys.Rev.,D51,3436,1995.R.Baier et al., Phys.Lett.,B243,432,1997.R.Baier et al., Nucl.Phys.,A661,205,1999

The suppression of the high- hadrons In AA collisions

Jet: A localized collection of

hadrons which come from a fragmenting parton

First data in first RHIC RUN

Jet Quenching ! Great!

For more observables see the next slides

Initial state effects (test experiment d+Au)

Suppression in central Au+Au due to final-state effects

/h

Au+Au @ sNN

= 200 GeV d+Au @ sNN

= 200 GeV

preliminary

Au+Au @ sNN

= 200 GeV d+Au @ sNN

= 200 GeV

preliminary

Au+Au @ sNN

= 200 GeV d+Au @ sNN

= 200 GeV

preliminary

Au+Au @ sNN

= 200 GeV d+Au @ sNN

= 200 GeV

preliminary

Again Au+Au and d+Au

If there are any other observables for Jet Quenching?

Correlation of trigger particles 4<pT<6.5 GeV withassociated particles 2<pT<pT,trig

Associated particles

Near side jetTrigger particle

Away side jet

Yes! Back to Back Jets correlation.

Kirill Filimonov, QM’04

Hadron meson puzzle (no suppression for protons?)

The aerogel detector is proposed for study identified particle at High pt and it was correct solution (1991).

Backup slides

Nuclear modification factor

is what we get divided by what we expect.is what we get divided by what we expect.

NN

biaryAAAA d

N/dR

From naive picture

AAR

1

0 d

*d

z

z)(Pd (...)f b/B(...)f a/A

(...)f b/B(...)f a/A

)Q,z(D 2d

*dd/h

)Q,z(D 2d

*dd/h

cdabd

cdabd

AAR

Suppression of high-pt hadrons. Qualitatively.

Jet tomography

20-60%

STAR Preliminry

20-60%

pTtrig=4.0-6.0 GeV/c, ||<1.02.0<pTassoc<pTtrig

Back-to-back suppression depends on the reaction plane orientation:

In-plane

Out-plane

Jet-pair Distributions

(deg.)0 20 40 60 80 100 120 140 160 180

<nab>

/<n a

><

n b>

0.000

0.002

0.004

0.006

Au+Au s 200 GeVCentrality 20 - 40 %

PHENIX Preliminary

color scheme:

pTtrig=2.5-4.0 GeV/c, ||<0.35

1.0<pTassoc<2.5 GeV/c

in-plane out-of-plane

energy loss dependence on the path length!

Kirill Filimonov, QM’04