Study of quark - gluon plasma production at the

ALICE detector, CERN

Chinorat KobdajSPC 2012

11 May 2012

What is heavy ion physics? What is ALICE?

quark Found in proton and neutron Bound by strong force Mediated by exchanging gluons No free quark has been observed

(confinement)

quark-gluon plasma (qgp) at very high

temperatures and/or very high densities

Tc ≈ 170 MeV ≈ 2000 billion K (compare Sun core: 15 million K)

Tc ~ 170 MeV

r~ 5 - 10 nuclear

Quark-Gluon Plasma

Hadron gas

Nuclearmatter

Neutron Star

SPSAGS

Early Universe LHCRHIC

Baryon density

Tem

pera

ture

ec ~ 1 GeV/fm3

~ 10 ms after Big Bang

How to make qgp? By colliding two heavy

nuclei at a speed close to the speed of light

as the system expands and cools down it will undergo a phase transition from QGP to hadrons again, like at the beginning of the life of the Universe

QGP lifetime ~ a few fm/c

Where can we do it? at the CERN Large Hadron Collider

What is ALICE? ALICE (A Large Ion Collider Experiment) It has been designed to work with a large

number of particles obtained form collisions of lead nuclei at the extreme energies of the LHC.

How can we see the qgp? Strange quarks are not component of

the colliding nuclei. But we have observed some strange

quarks in the collision. This is called Strangeness enhancement.

Strange quarks or antiquarks observed have been created from the kinetic energy of colliding nuclei.

Therefore, we look at the strangeness enhancement as a signature for quark gluon plasma

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Strange Particles Strange particles are hadrons

containing at least one strange quark. For example

(d) kaonΛ (uds) hyperon

V0 decay pattern The starting particle disappears from

the interaction point and two oppositely charged particles appear in opposite directions

→ π+π-

Λ→ p + π-

Cascade decays Ξ- decays into π- and Λ Then the Λ then decays into π- and

proton Ξ-→π-Λ→ π- p + π-

30 เม.ย. – 1 พ.ค. 2555 Karel Šafařík: ParticleTracking Karel.Safarik@cern.ch 15

Bubble chambersW– in 2-m CERN hydrogen bubble chamber

1973

1630 เม.ย. – 1 พ.ค. 2555Karel Šafařík: ParticleTracking

Karel.Safarik@cern.ch

Bubble chambers D* in BEBC hydrogen bubble chamber1978

1730 เม.ย. – 1 พ.ค. 2555Karel Šafařík: ParticleTracking

Karel.Safarik@cern.ch

Streamer chamberp+m+e+ decay in streamer chamber

1984

1830 เม.ย. – 1 พ.ค. 2555Karel Šafařík: ParticleTracking

Karel.Safarik@cern.ch

Streamer chamber6.4 TeV Sulphur - Gold event (NA35)

1991

Today there are so many tracks.2010

How can we do it? By the help of computer Simulation software Interface with the detectors

LHC Computing Grid The data stream from

the detectors provides approximately 300 GB/s

27 TB of raw data per day or 10–15 PB of data each year

These data is more than any single, current, system can handle

Scientists look at a computer screen at the control centre of the CERN in Geneva September 10, 2008. (Xinhua/Reuters Photo)

We need to find the system that can handle massive amounts of data can process large computing jobs relatively inexpensive simple to use can access 24/7 easily upgraded

Why don’t we build a super Computers ?

very expensive very difficult to access obsolete quickly

http://gizmodo.com/298029/worlds-biggest-supercomputer-is-a-virus

Solution: using the Internet ?

A Computing Grid

GridPP masterclasstalk2009

What is middleware? Middleware is a computer software that allows users to submit jobs to the Grid

without knowing where the data is or where the jobs will run. The software can run the job where the data is, or move the data to where there is CPU power available.

How to set up LHC GRID site?

The basic LCG site consists of UI User Interface CE Compute Element WN Worker Nodes SE Storage Element Site BDII Berkley

Database Information Index MON Monitor Accounting service

Operating system SLC5

Middleware The gLite middleware is produced by

the EGEE project.

Computing model at ALICE

Computing frameworkSimulationReconstructionData analysis

Main software Root Aliroot Geant3

ROOT framework

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AliRoot framework

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• Modularity

• Re-usability

Event generators : HIJING DPMJET PYTHIAALICE have developed

a generators base class called AliGenerator.

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Detector response simulation

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Simulation process : Event generation of final-state particles Particle transport Signal generation and detector response Digitization Fast simulation

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Analysis tools Statistical tools Calculations of kinematics variables Geometrical calculations Global event characteristics Comparison between reconstructed and

simulated parameter Event mixing Analysis of the HLT data visualization

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ALICE Physics Working Group

1. PWG-PP Detector Performance2. PWG-CF Correlations Fluctuations Bulk 3. PWG-DQ Dileptons and Quarkonia 4. PWG-HF Heavy Flavour 5. PWG-GA photon and pion working group6. PWG-LF Light Flavour Spectra7. PWG-JE Jets 8. PWG-UD

1. PWG-PP Detector Performance Quality Assurance Calibration Event Characterization Particle Identification Event and Track Selections Tracking and Alignment Run Conditions

Embedding and mixing Monte Carlo

2. PWG-CF Correlations Fluctuations Bulk

Correlations Event-by-Event / Fluctuations Femtoscopy Flow

3. PWG-DQ Dileptons and Quarkonia Lmee Low Mass Dielectron Lmmumu Low Mass Mumu Jpsi2ee J/ψ to e+e- at mid-rapidity Jpsi2mumu J/ψ to Mumu Upsilon2mumu Upsilon to mumu

* 4. PWG-HF Heavy Flavour HFE Electrons from HF decays D2H Fully reconstructed charm hadron

decays HFM Muon from HF decays

5. PWG-GA photon and pion working group

Gamma and Neutral Pions

6. PWG-LF Light Flavour Spectra GEO Global Event Observables Resonances Spectra Strangeness

7. PWG-JE Jets

8. PWG-UD Ultraperipheral, Diffractive, Cross

section and Multiplicity, and CosmicsUltra Peripheral CollisionsCross section and MultiplicityDiffraction Cosmics

Acknowledgement Suranaree University of Technology Thailand Center of Excellence in

Physics (ThEP) National Electronics and Computer

Technology Center