• The PHENIX experiment

• Role of the Particle Identification at high Pt

• Aerogel Cerenkov detector

• Design

• Test-beam performance

• Outlooks

Extended Pid in PHENIX(BNL, Dubna, Tokyo, Tsukuba)

E.Kistenev

for the PHENIX High Pt Upgrade Project

CIPANP 2003

tracking:

DC,PC1, PC2, PC3

electron Id:

RICH, EMCal, TEC

photons:

EMCal

charged hadron Id:

Aerogel, RICH, TEC, EMCal

PHENIX at RHIC

Extending PHENIX ReachExtending PHENIX Reach

Extending Pid to 10 GeV/c will enhance– Jet tagging – initial vs final state partonic evolution;– Charm & beauty measurement in Au+Au collisions ->

energy loss of charm/beauty in hot matter;G measurement by heavy quark production in wide x

range;– Gluon shadowing in wide x range

Present pT range with PID :/K up to 2 GeV/c p/(+K) up to 4.5 GeV

PHENIX High Pt Upgrade Project

Aerogel detector building blocks

Goal: K-threshold close to 5 GeV/c

Cherenkov emission in Aerogel

• It is Cherenkov Emission.

2

22

2max1

1p

pm

nNN

Light yield vs Momentum Light Yield vs Refractive index

N photonvisible 500sin2 c [1/cm]

c Cos 1(1

n)

Nmax 500 q.e.12 [cm]

1200 p.e.Data from Belle, slide from Ya. Miake

PHENIX Aerogel n=1.012

Aerogel Detector R&D – Test Beam at KEK

Light Yeld Dependence on Aerogel Stack Thickness

• Light Yield saturates at ~ 12 cm depth

• Scattering dominates in light losses

3 GeV/c pions

n = 1.017

R6233(3”,non-UV)

L

scatt 4 , abs 2

Uniformity of the Light YIeld

N=1.014

Light yield and counter orientation

Aerogel

Beam direction

Timing in aerogel detector

-better then the counter size track matching

-background rejection

Subnanosecond resolution measured when timing on first photoelecton

PHENIX PID in Run4 and beyond …

Pion-Kaon

separation

Kaon-Protonseparation

TOF ~100 ps 0 - 2.5 - 5

RICH n=1.00044

th~34

5 - 17 17 -

Aerogel n=1.01

th~8.5

1 - 5 5 - 9

0 4 8

0 4 8

0 4 8 0 4 8

0 4 8

0 4 8