Review of ALICE Experiments (Jin-Hee Yoon) Dept. of Physics - - PowerPoint PPT Presentation

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Review of ALICE Experiments (Jin-Hee Yoon) Dept. of Physics - - PowerPoint PPT Presentation

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Review of ALICE Experiments (Jin-Hee Yoon) Dept. of Physics 2017. 6. 17 @ 2 Outline Introductjon Review of Alice Results ITS upgrade Conclusion Objects Searching for the

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Review of ALICE Experiments

尹 珍 姬 (Jin-Hee Yoon)

  • Dept. of Physics
  • 2017. 6. 17 @ 제

2 회 대칭성 탐사단 워크샾

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Outline  Introductjon  Review of Alice Results  ITS upgrade  Conclusion

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Objects  Searching for the initjal stage of Universe  From QCD calculatjon,

­ Confjning at normal temperature

 At high momentum transfer

αS becomes weak asymptotjc freedom Quark-Gluon Plasma(QGP)

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Lattjce QCD Calculatjon  15 MeV GeV/fm3 

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Phase Diagram

Temperature net baryon density Early universe nuclei nucleon gas hadron gas quark-gluon plasma (QGP) Tc

ρ0

Colour super conductor neutron stars

RHIC, LHC

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How to produce?

Theoretjcally Experimentally

Heavy Ion Collision

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Evolutjons

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QGP in the Universe

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Observables?  High energy process

­ Energy loss by quarks, gluons and other partjcles ­ Quarkonia and heavy fmavour

 Low energy process

­ Radiatjon of hadrons and photons (multjplicity, pT spectra, PDF..) ­ Azimuthal asymmetry, expansion

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Variables  Center of Mass Energy  Rapidity  Pseudo Rapidity  At high energy, 

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A Large Ion Collider Experiment Detector : 16X26 m 10000 tons Collaboratjons : 1500 members, 154 instjtute, 37 countries

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ALICE COLLABORATION

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Partjcipatjng Instjtutes

Participants (39)

  • 6 Univs. + 1 Insti-

tute

  • Prof : 10
  • PhD : 5
  • Graduates : 24

Korea-CERN Symposium

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Collisions

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2015 Pb-Pb Event Display

p P b @ 5 T e V

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Centrality “Peripheral” Large impact parameter Small system volume Small partjcle multjplicity “Central” Small impact parameter Large system volume Large partjcle multjplicity

Map these measurements into IP using Models!

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Charged partjcle multjplicity

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Sofu Probes – Direct photons  Inclusive – Decay = Direct  Prompt

­ Hard scatuering ­ High pT ­ Informatjon on PDF, QCD…

 Thermal

­ Thermal productjon ­ Low/medium pT ­ Informatjon on early thermal state(QGP?)

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Radial Flow Thermal + Collectjve expansion velocity MeV

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PT spectra of charged partjcles  Get fmatuen for more central  Stronger efgect for heavier partjcles  Heavier partjcles have larger momentum with same velocity

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Elliptjc Flow Spatjal anisotropy Anisotropy in momentum space

SCIENCE Vol: 298 2179 (2002) 7Li

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Elliptjc Flow  v2@LHC is 30% larger th an @RHIC.  Transfer of the anisotrop y from in space to in mo mentum space  viscosi ty info.  =0.2 (perfect fmuid) 

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Strangeness Enhancement  In elementary pp collisions,  Strangeness products are suppressed relatjve to the productjon

  • f light fmavors

 For a large system, strangeness is enhanced.  How to confjrm?

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Nuclear Modifjcatjon Factor  : enhancement   : suppression 

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Hard Probes – Jet Quenching

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QUARKONIA  : pair of c & antj-c

­ Inside the QGP, quarks are color-screened  suppression ­ Debye length depends on Temp.  thermometer

Phenix µµ ALICE µµ

Less suppression than RHIC due to recombinatjon

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QUARKONIA  Suppression is independent of centrality.  Need to measure total charm productjon around pT~0 GeV.

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Small systems as reference? Nuclear initjal state Hot matuer in the fjnal state Nuclear initjal state Cold matuer in the fjnal Hadronic initjal & fjnal state  No phase transitjon in pp or pA collisions is expected.  But striking similarity across difgerent systems!

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Strangeness

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The pT spectra become harder as the multiplicity increases.

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  • No baryon number dependency.
  • No mass dependency.
  • No MC models cannot reproduce this result.
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ITS Upgrade  Improve IP resolutjon by 3~5 tjmes

­ Closer to IP : 39 mm  23 mm ­ Reduce the material budget : 1.14%  0.3 % ­ Spatjal resolutjon : 12mmX100mm  5mmX5mm

 Improve tracking effjciency and pT resolutjon at low pT

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Conclusion  Heavy-ion collisions during RUN1 and RUN2 periods.

­ Energy density ~ 15 GeV/fm3 >> ­ T=300 MeV ­ Elliptjc fmow from hydro-dynamics  QGP as a perfect fmuid ­ suppression smaller than at RHIC  dissociatjon + recombinatjon

 Similaritjes among difgerent systems (pp,p-Pb, Pb-Pb)

­ Collectjvity in small systems? ­ Strangeness enhancement from low to high multjplicity pp collisions

 Need high precision measurements of the productjon of heavy quarks, quarkonia, jet and di-leptons over a large momentum ra

  • nge.  Looking forward to Upgrades