Mini Bang at Big Accelerators Prashant Shukla Institute of Physics University of Heidelberg Presentation at ISA, 30 January 2005, Heidelberg, Germany

Outline ● What is an Atom, Nucleus ? ● Nuclear Physics Experiment ? ● A Particle Accelerator ? ● A Nuclear Detector ? ● Structure within nucleus ? ● New state of matter- Quark Gluon Plasma ● History of the Universe ● The Idea of the Big Bang ● Big Bang in Lab ● Large Hadron Collider (LHC) at CERN ● The ALICE Experiment ● The TRD (Transition Radiation Detector) ● Computer Simulations ● The studies done on the computer

An Atom The smallest unit of any substance which decides ist chemical properties e e e e Nucleus size ~ 10^(-14) meter Atom ~ 10^(-10) meter

The Nucleus All the mass of atom is inside nucleus

Nuclear Physics Experiment Energetic particles are used to see the nucleus and ist constituent which can not be seen by any optical microscope. Alpha particle Gold nucleus Charge = +79 Detector Smaller the size you want to probe larger the energy of the probe particle

A Particle Accelerator A charged particle when passes through a high voltage difference it gains energy or accelerated Energy Gained E = qV +q +V An electron passes through 1 volt gains 1 eV of energy 1 MeV = 10^6 eV 1 TeV = 10^12 eV

Modern Particle Accelerator Time Voltage

A Multi-Accelerator Complex The Relativistic Heavy Ion Collider – RHIC 100 A GeV 1 A MeV 95 A MeV 10.8 A GeV PHENIX

Relativistic Heavy Ion Accelerators in the world

A Detector +V -V

Structure within nucleus Ordinary matter is made of up and down quarks

Force between two quarks Compare to gravitational force at Earth’s surface Quarks exert Kg of force on each other! quark gluons

Introduction to Quark Gluon Plasma Quarks are Freely moving inside proton but, Forbidden to come outside Hadrons Phase Transition QGP Proton q q q  Increase hadron Density --- Compressing  Or increase K. E. of hadrons --- Heating The unverse is supposed to have started from this soup n p pi n p pi p n pi p q g qq g q qq q q g qq g q qq q

History of the Universe Weber

The Idea of the Big Bang Weber Three main ideas under the big bang model The universe cools as it expands In very early times, the universe was mostly radiation The hotter the universe, the more energetic photons are available to make matter and anti- matter The full story can be emerged if we produce conditions similar to BIG BANG: Produce a temperature of 10^13 K

How to produce heat

Heavy Ion Collisions Weber PARTICLES! , e+e -,  +    K  p  n   D  d, J/Y,…

LHC at CERN SPS Pb upto 20 AGeV LHC 2007 upto 5.5 ATeV

The ALICE Experiment ITS Low p t tracking Vertexing TPC Tracking, dEdx TRD Electron ID TOF PID HMPID PID high p t PHOS ,  0 MUON  -pairs PMD  multiplicity Y X Z

Expected dilepton invariant mass spectrum (Schematic) Heavy Ion Collisions at LHC 5.5 TeV

The TRD (Transition Radiation Detector) ● 18 supermodules in phi sector ● 6 Radial layers ● 5 Z longitudinal stack  540 chambers  750m 2 active area  28m 3 of gas in total 1.18 million read out channels |eta| < <Theta <135

TRD Stack used in CERN test beam

AliRoot Simulations dNch/d  ~ 8000 (slice: 2 o in  TPC 5000 PbPb events at 5.5 TeV/nucleon pair ITS PHOS TRD TOF HMPID

Particle identification with TRD ● Transition Radiation photons are generated by charged particles crossing the border between two different di- electric media ● Elektron-/pion-discrimination: (p = 5 GeV/c): e - g ~ pi  ~ 36

Pi efficiency vs electron efficiency

Invariant Mass spectrum e+e- invariant mass Signal/noise with pt-cut

Summary ● What is an Atom, Nucleus. ● Nuclear Physics Experiment. Accelerator, Detector. ● Structure within nucleus ? ● New state of matter- Quark Gluon Plasma ● History of the Universe ● Big Bang in Lab ● LHC at CERN, ALICE Experiment ● Computer Simulations ● The studies done on the computer