Relativistic Heavy Ions Experiment II Global Observables.

Relativistic Heavy Ions

Experiment II

Global Observables

Participant – Spectator Scenario

NA49 Trigger Setup

NA49 Target Area

NA49 Ring Calorimeter

NA49 Veto Calorimeter

Hadronic Calorimeter

Distributions of Nch and ET

Correlation EF and ET

Centrality Classes

Centrality Selection via Multplicity: WA97 / NA57

Centrality Selection via Multplicity: WA97 / NA57

Beam-Beam

Counter atRHIC

Beam-Beam Counter at RHIC

Zero Degree Calorimeter (ZDC) at RHIC

Centrality Selection at RHIC

ET Distribution

Energy Density (Bjørken)

Wounded Nucleon Scaling

Participant Scaling

Energy Density

Stopping

yP yT

y0

y y

y0

yP yT

y y y’Ty’p

Baryonnumber distributionsLower energies: Higher energies:

Stopping

NA49

Observable: net-proton distributions

Stopping

Energy Dependence of y

py BB

partp

p

dydy

dNy

Ny

yyy

0

)(2

Linear increase up to SPS: y /ybeam 0.27

Rapidity shift:

dyydy

dNmE BBy

y yT

p

p

cosh)(

Energy loss E :

RHIC (sNN = 200 GeV):E = 25.7 ± 2.1 TeV E/Nucleon = 72± 6 GeV

Rapidity-Distributions of Baryons

Central Pb+Pb, 158 AGeV

Net-protons: 3 Valence Quarks (uud )

Omegas: 3 produced Quarks (sss )

Net s:1 Valence (d ) + 2 produced Quarks (ss )

Net s:2 Valence (ud ) +1 produced Quark (s )

NA49

dn

/dy (

a.u

.)

y