Henrik Tydesjö March 17 2003

OUTLINEOUTLINE

- The Quark Gluon Plasma

- The Relativistic Heavy Ion Collider (RHIC)

- The PHENIX Experiment

- Event-by-Event Net-Charge Fluctuations Simulations PHENIX Analysis

Henrik Tydesjö March 17 2003

QUARK GLUON PLASMAQUARK GLUON PLASMA

At extremely High Densities & TemperaturesNuclear Matter may undergo a Phase Transitionto a state called the Quark Gluon Plasma (QGP)

Henrik Tydesjö March 17 2003

QUARK GLUON PLASMAQUARK GLUON PLASMA

DECONFINEMENTDECONFINEMENT

PHASETRANSITION

Henrik Tydesjö March 17 2003

QUARK GLUON PLASMAQUARK GLUON PLASMA

CHIRAL SYMMETRY

RESTORATION

CHIRAL SYMMETRY

RESTORATION

Quark Masses 0

Henrik Tydesjö March 17 2003

Phase Diagram of Nuclear MatterPhase Diagram of Nuclear Matter

Early Universe

HadronGas

QGP

Neutron StarsNeutron Stars??????

Ultra-RelativisticHeavy-Ion Collisions

???

Henrik Tydesjö March 17 2003

Relativistic Heavy Ion Collider (RHIC)Relativistic Heavy Ion Collider (RHIC)

Brookhaven, Long Island, New York

Henrik Tydesjö March 17 2003

Relativistic Heavy Ion Collider (RHIC)Relativistic Heavy Ion Collider (RHIC)Au+Au Collisions 100 AGeV per

beam

Henrik Tydesjö March 17 2003

~ 460 Members

57 Institutions

12 Countries

~ 460 Members

57 Institutions

12 Countries

Collaboration

Henrik Tydesjö March 17 2003

Central Magnet

Beam-BeamCounters

Muon ArmSpectrometers Central Arm

Spectrometers

Henrik Tydesjö March 17 2003

Central Arms

Pad Chambers

Charged ParticleTracking

Electron, Photon Detection

Hadron Identification

Henrik Tydesjö March 17 2003

Pad Chambers- Multi-Wire Proportional Chambers

- Fine Granularity Pixel Pad Readout

- Provide Space Points for Track Recognition

Henrik Tydesjö March 17 2003

Pad Chambers- Multi-Wire Proportional Chambers

- Fine Granularity Pixel Pad Readout

- Provide Space Points for Track Recognition

- 172,800 Readout Channels

- Chip-On-Board Technique

Readout Cards (ROCS) Placed on the Chambers

- Data Transfer via Fiber Optic Links

Readout Card (ROC)

Henrik Tydesjö March 17 2003

Event Display

CentralAu+Au

Collision

370globaltracks

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

Event-by-EventNet Charge Fluctuations

in Local Regions of Phase Space

Decrease of Fluctuationsproposed as a signal for the QGP

Predictions range up to an 80% reduction

Henrik Tydesjö March 17 2003

Hadronization

???

Pion GasPion Gas

QGPQGP

NET CHARGE FLUCTUATIONS

+ 1/3

+ 2/3+ 1

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

Charge Q in each event:

nnQ

Variance of Q:

22)( QQQV

Random Particle Emission:

chnnnQV )(

chn

QVQv

)()(

Normalized Variance:

Henrik Tydesjö March 17 2003

1000 particles per event

assigned: charge +1 or –1 ,

azimuthal angle

NET CHARGE FLUCTUATIONS

SIMULATION

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

SIMULATION

Charge is globally conservedapQv 1)(

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

SIMULATION

Efficiency Dependenceea ppQv 1)(

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

SIMULATION

Uncorrelated Background Contribution)1(1)( bkga fpQv

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

SIMULATION

Decays of Neutral Resonances (e.g. , )introduce positive correlations between n+ and n–

width = 30º

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

SIMULATION

Decays of Neutral Resonances

fres = 0.3

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

SIMULATION

Simple QGP model:yprobabilit equal with hadronize ,,, nscombinatioquark ddudduuu

producing 2 or 3 pions, separated in azimuth (Gaussian width=10º)

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

RHIC 1st run period

GeVsNN 130

~ 500 000 events

|zvertex| < 17 cm

pT > 200 MeV/c

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

BBCs used for triggering

corresponding to 92% of inelastic cross-section

Centrality classes

determined from BBC+ZDC information

0-5%5-10%

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

pT , of positive and negative particles

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

Reduction not as large as predicted for QGPConsistent with resonance gas

Global ChargeConservation

10% most central events

Henrik Tydesjö March 17 2003

NET CHARGE FLUCTUATIONS

Fluctuations independent of centrality

)(019.0)(007.0965.0)( syststatQv 10% most central events:

Henrik Tydesjö March 17 2003Henrik Tydesjö March 17 2003

SUMMARYSUMMARY- An introduction was given to: Quark Gluon Plasma Relativistic Heavy-Ion Collider (RHIC) PHENIX Experiment

- The behavior of Net-Charge Fluctuations in different scenarios was described in simulations

- Results on Net-Charge Fluctuations in PHENIX was presented: Fluctuation result below pure global charge conservation Reduction not as drastic as predicted for a QGP Consistent with resonance gas prediction

Henrik Tydesjö March 17 2003