Event By Event Physics In Alice
Transcript Of Event By Event Physics In Alice
EVENT BY EVENT PHYSICS IN ALICE
Panos Christakoglou NIKHEF - Utrecht University for the ALICE Collaboration
12/9/2008
[email protected] - WPCF, Krakow
1
MOTIVATION
The nature and the time evolution of the hot and dense system created in a heavy-ion collision are expected to show the characteristic behavior of a QGP phase transition, which could dramatically change from one event to the other.
Apart from the very well known probes (inclusive probes, probes related to deconfinement...), an analysis on an Event by Event basis offers the opportunity to study the QCD phase transition and to get insights into the QGP. For example:
Thermodynamic quantities (T,S) Energy density fluctuations Jets and minijets DCC, Balance function...
Global system properties Order of phase transition Medium properties Chiral phase transition, hadronization time...
12/9/2008
[email protected] - WPCF, Krakow
EXPERIMENTAL SETUP – CENTRAL BARREL
HMPID
PID (RICH) @ high pt Coverage: |η| < 0.6 – φ: 57.61o
TOF
PID Coverage: |η| < 0.9 – φ: 2π
TRD
Electron ID Coverage: |η| < 0.9 – φ: 2π
TPC
Tracking, dEdx Coverage: |η| < 0.9 – φ: 2π
PHOS
Detection of photons Coverage: |η| < 0.12 – φ: 100o
ITS
Low pt tracking Vertexing
ITS
Coverage: |η| < 2.0 – φ: 2π (SPD ) Coverage: |η| < 0.9 – φ: 2π (SDD++SSD)
12/9/2008
[email protected] - WPCF, Krakow
3
EXPERIMENTAL SETUP – FORWARD DETECTORS
Multiplicity • FMD • V0 • PMD (photons) (-3.7 < η < -2.3) • charged (barrel+FMD): (-5.4 < η < 3)
Forward muon arm (2.4 < η < 4.0) • absorber, dipole magnet • tracking and trigger chambers
Trigger, timing, luminosity: • ZDC, V0, T0, CRT
EM Calorimeter (future)
(charged particles)
12/9/2008
[email protected] - WPCF, Krakow
4
PARTICLE IDENTIFICATION
Many identification techniques 3σ and 2σ separation between particle species
512/9/2008
Estimated pT ranges for 10 M central PbPb events (PPR vol. II). Ranges for first year p-p events can be close if one month of data taking.
[email protected] - WPCF, Krakow
CENTRALITY DETERMINATION
Correlation between the deposited energy in the ZDC and the multiplicity measured in the central (ITS+TPC) and forward regions (FMD).
12/9/2008
[email protected]h - WPCF, Krakow
6
ALICE PERFORMANCE
Efficiencies vs. pT: i) p+p and Pb+Pb comparison; ii) species dependence dE/dx resolution for PID: i) dE/dx vs. # of TPC cluster; ii) dE/dx vs. pT
ALICE is designed for high multiplicity: excellent efficiency and resolution at low pT Charm and strange weak decay identification via topology reconstruction (not shown) Lower magnetic field w-r-t ATLAS and CMS but also lower luminosity conditions required
712/9/2008
[email protected] - WPCF, Krakow
EVENT BY EVENT STUDIES IN ALICE
Net charge fluctuations
Multiplicity fluctuations
Transverse momentum fluctuations
Balance functions
Particle ratios
Temperature fluctuations
Long range correlations
Flow
HBT
DCC Wavelets
With red what is not addressed in this talk!
.
.
12/9/2008
[email protected] - WPCF, Krakow
8
NET CHARGE FLUCTUATIONS
Fluctuations of conserved quantities such as the electric charge provide information about the initial stage of the formation of the system after a collision, when possibly a system with different degrees of freedom existed.
NA49: Phys. Rev. C 70 064903 (2004)
G. Westafall: QM08
• ΔΦq values close to 0 as expected for a pion gas correlated only by global charge conservation. • The existence of resonances may mask the initial fluctuations.
• Scaling of the νdyn with multiplicity apparent for different systems/energies.
12/9/2008
[email protected] - WPCF, Krakow
9
NET CHARGE FLUCTUATIONS IN ALICE
D parameter of net charge fluctuations
Higher moments of net charge fluctuations
HIJING PbPb events @ √sNN = 5.5 TeV
Courtesy of Tapan Nayak & Marian Putis
PYTHIA pp events @ √s = 900 GeV and 14 TeV
Plans for ALICE • Provide the possibility to calculate as many parameters as possible:
o D – ΔΦq - νdyn • Calculate also the higher moment
o skeweness (3rd moment) o kurtosis (4th moment)
12/9/2008
[email protected] - WPCF, Krakow
10
Panos Christakoglou NIKHEF - Utrecht University for the ALICE Collaboration
12/9/2008
[email protected] - WPCF, Krakow
1
MOTIVATION
The nature and the time evolution of the hot and dense system created in a heavy-ion collision are expected to show the characteristic behavior of a QGP phase transition, which could dramatically change from one event to the other.
Apart from the very well known probes (inclusive probes, probes related to deconfinement...), an analysis on an Event by Event basis offers the opportunity to study the QCD phase transition and to get insights into the QGP. For example:
Thermodynamic quantities (T,S) Energy density fluctuations Jets and minijets DCC, Balance function...
Global system properties Order of phase transition Medium properties Chiral phase transition, hadronization time...
12/9/2008
[email protected] - WPCF, Krakow
EXPERIMENTAL SETUP – CENTRAL BARREL
HMPID
PID (RICH) @ high pt Coverage: |η| < 0.6 – φ: 57.61o
TOF
PID Coverage: |η| < 0.9 – φ: 2π
TRD
Electron ID Coverage: |η| < 0.9 – φ: 2π
TPC
Tracking, dEdx Coverage: |η| < 0.9 – φ: 2π
PHOS
Detection of photons Coverage: |η| < 0.12 – φ: 100o
ITS
Low pt tracking Vertexing
ITS
Coverage: |η| < 2.0 – φ: 2π (SPD ) Coverage: |η| < 0.9 – φ: 2π (SDD++SSD)
12/9/2008
[email protected] - WPCF, Krakow
3
EXPERIMENTAL SETUP – FORWARD DETECTORS
Multiplicity • FMD • V0 • PMD (photons) (-3.7 < η < -2.3) • charged (barrel+FMD): (-5.4 < η < 3)
Forward muon arm (2.4 < η < 4.0) • absorber, dipole magnet • tracking and trigger chambers
Trigger, timing, luminosity: • ZDC, V0, T0, CRT
EM Calorimeter (future)
(charged particles)
12/9/2008
[email protected] - WPCF, Krakow
4
PARTICLE IDENTIFICATION
Many identification techniques 3σ and 2σ separation between particle species
512/9/2008
Estimated pT ranges for 10 M central PbPb events (PPR vol. II). Ranges for first year p-p events can be close if one month of data taking.
[email protected] - WPCF, Krakow
CENTRALITY DETERMINATION
Correlation between the deposited energy in the ZDC and the multiplicity measured in the central (ITS+TPC) and forward regions (FMD).
12/9/2008
[email protected]h - WPCF, Krakow
6
ALICE PERFORMANCE
Efficiencies vs. pT: i) p+p and Pb+Pb comparison; ii) species dependence dE/dx resolution for PID: i) dE/dx vs. # of TPC cluster; ii) dE/dx vs. pT
ALICE is designed for high multiplicity: excellent efficiency and resolution at low pT Charm and strange weak decay identification via topology reconstruction (not shown) Lower magnetic field w-r-t ATLAS and CMS but also lower luminosity conditions required
712/9/2008
[email protected] - WPCF, Krakow
EVENT BY EVENT STUDIES IN ALICE
Net charge fluctuations
Multiplicity fluctuations
Transverse momentum fluctuations
Balance functions
Particle ratios
Temperature fluctuations
Long range correlations
Flow
HBT
DCC Wavelets
With red what is not addressed in this talk!
.
.
12/9/2008
[email protected] - WPCF, Krakow
8
NET CHARGE FLUCTUATIONS
Fluctuations of conserved quantities such as the electric charge provide information about the initial stage of the formation of the system after a collision, when possibly a system with different degrees of freedom existed.
NA49: Phys. Rev. C 70 064903 (2004)
G. Westafall: QM08
• ΔΦq values close to 0 as expected for a pion gas correlated only by global charge conservation. • The existence of resonances may mask the initial fluctuations.
• Scaling of the νdyn with multiplicity apparent for different systems/energies.
12/9/2008
[email protected] - WPCF, Krakow
9
NET CHARGE FLUCTUATIONS IN ALICE
D parameter of net charge fluctuations
Higher moments of net charge fluctuations
HIJING PbPb events @ √sNN = 5.5 TeV
Courtesy of Tapan Nayak & Marian Putis
PYTHIA pp events @ √s = 900 GeV and 14 TeV
Plans for ALICE • Provide the possibility to calculate as many parameters as possible:
o D – ΔΦq - νdyn • Calculate also the higher moment
o skeweness (3rd moment) o kurtosis (4th moment)
12/9/2008
[email protected] - WPCF, Krakow
10