Relativistic Heavy Ions

Experiment III

Strangeness and Heavy Flavour

V0-Topology

K0

Kink-Topology

K±

Discovery of Strange Particles

-

K0

-

p

+

-

Associated Productionof Strange Particles

K- + p 0+ K0

0 (S = -1, weak interaction) p+ - (S = -1, weak interaction)

Multiple Strange Particles: (Cascades)

Main Strangeness Carriers in A+A Collisions: K and

s s=

Strangeness Conservation

K0 (ds)K+ (us)

Isospin Symmetry

K- (us) K0 (ds)Isospin Symmetry

(uds) (uds)

>>

>>

If baryon density is high

Multiple Strange Particles from String Fragmentation

M. Bleicher et al.,Phys. Rev. Lett. 88 (2002), 202501

Strange Particle Production by qq- and Gluon-Fusion

Particle Identification in NA49

dE/dx measured in TPCs Large acceptance Resolution 3-4%

Time-of-flight Mid-rapidity Resolution 60 ps

Example:Pb+Pb @ 40 AGeV

p

dE/d

x

Time Projection Chamber: NA49

Main-TPC

Field cageVertex-TPC

TPC (NA49): Working Principle

High Voltage-Electrode (100 kV)

Fieldcage

Readout Chamber

Time Projection Chamber: ALICE

Volume: 88 m3

Drifttime 88 s Number of readout

channels: 570132

E-FieldE-Field

510 cm

ALICE-TPC

TPC (ALICE): Working Principle of Readout Chambers

Gas amplification at the anode wires

Induced signal on pads: x/y-coordinates

Drifttime z-coordinates

Signalheight Energy loss of particles Particle identification

beam axis

Strangeness via V0 Topology

Invariant Mass Spectra of K0s, -,- in Pb+Pb

minv(+,-) (GeV/c2)

Entr

ies

En

trie

s

K0s

-

NA57 @ SPS

NA57 Setup

Strange Particle Reconstruction in NA57

Si Pixels

telesc

ope

target

1 M ch

annels

B

30 cm

5 cm

5 cm

1.4 T

60 cm

Strangeness Enhancement by NA57

Strangeness Enhancement by NA57

Energy Dependence of Particle Ratios

5.1

K+/+

K-/-

/

/

-/

-++/

UrQMD + HSDE.L. Bratkovskaya et al.,PRC 69 (2004), 054907

Statistical hadron gas:P. Braun-Munzinger,J. Cleymans, H. Oeschler, and K. RedlichNucl. Phys. A697 (2002) 902

s = 1

Heavy Flavour

M. Mangano, hep-ph/0411020

Beauty Production at the Tevatron (Run1+2, 2003)

Jet Quenching

Energy Loss of Heavy Quarks

light

(M.Djordjevic PRL 94 (2004))

acceptance: pt > 0.2 GeV/cr < 50 m for pt > 1.5 GeV/c

D0 K+ + -

c ~ 124 m

Reconstruction of D-Mesons

D-Mesons w/o Vertex-Reconstruction

Energy Dependence of cc-Cross section

PrimaryVertex B

e

Xd0

rec. track

B e + Xc ~ 500 msemi-leptonic

Reconstruction of B-Mesons

B J/ + X

Reconstruction of B-Mesons

Transition Radiation

Produced by charged particles passing the border between two media of different di-electricity constant

Predicted by V.L. Ginzburg and I.M. Frank 1946

Properties: Energyspectrum in keV-region Emissionangle ~1/ (Lorentz-Factor)

Spectrum and yield determined by: Number and distance of borders Thickness and plasma frequency of

materials Velocity of charged particle

() Possible radiators:

Regular foil stack Fiber materials Foam-like materials

measuredspectrum for electrons with 2 GeV/c momentum

Zählgas: Xe/CO2

Driftlänge: 3cm

Transition Radiation Detector

Electron-/pion-discrimination:

e- (p = 5 GeV/c): 10000

- (p = 5 GeV/c): 36

Radiator made of microfibersPolypropylene, 17 m

TRD Setup in ALICE

TRD in numbers: 540 chambers 6 planes 18 sectors

(supermodule) Total area: 736 m2

(3 tennis courts) Gasvolume: 27,2 m3

Resolution (r) 400 m

Number of read out channels: 1.2 106

TRD Supermodule

TPC

Expected Di-Electron Spectrum