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International Workshop on Heavy Ion Physics at LHC Photon Physics with PHOS at Center China of Normal University Institute of Particle Physics May 21-24,

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Presentation on theme: "International Workshop on Heavy Ion Physics at LHC Photon Physics with PHOS at Center China of Normal University Institute of Particle Physics May 21-24,"— Presentation transcript:

1 International Workshop on Heavy Ion Physics at LHC Photon Physics with PHOS at Center China of Normal University Institute of Particle Physics May 21-24, 2008, Wuhan, China Toru Sugitate / Hiroshima Univ.

2 Outline of the Talk Photon sources and physics Lessons from RHIC Reality and strategy for the 1 st years Conclusion

3 Toru Sugitate / Hiroshima Univ. / KEK page 3 Time Line of the Universe Photons: the important probe to explore the nature

4 Toru Sugitate / Hiroshima Univ. / KEK page 4 hadronic photons Calc. w/ pQCD, eg. PYTHIA meson decays in jets Parton Distribution Function (PDF) Subprocess cross section calculated with pQCD Fragmentation Function (FF) Photons in pp & AA collisions pQCD photons Precise calc. w/ pQCD Isolated photons Only little abundance prompt photons in AA Calc. w/ Lattice QCD Thermal photons: QGP and HG p~T~GeV

5 Toru Sugitate / Hiroshima Univ. / KEK page 5  Global observables: Multiplicities,  distributions  Degrees of freedom as a function of T: hadron ratios and spectra, dilepton continuum, direct thermal photons  Early state manifestation of collective effects: elliptic flow  Energy loss of partons in quark gluon plasma: jet quenching, high pt spectra, open charm and open beauty  Deconfinement: charmonium and bottonium spectroscopy  Chiral symmetry restoration: neutral to charged ratios, res. decays  Fluctuation phenomena - critical behavior: event-by-event particle comp. and spectra  Geometry of the emitting source: HBT, impact parameter via zero-degree energy flow  pp collisions in a new energy domain  Global observables: Multiplicities,  distributions  Degrees of freedom as a function of T: hadron ratios and spectra, dilepton continuum, direct thermal photons  Early state manifestation of collective effects: elliptic flow  Energy loss of partons in quark gluon plasma: jet quenching, high pt spectra, open charm and open beauty  Deconfinement: charmonium and bottonium spectroscopy  Chiral symmetry restoration: neutral to charged ratios, res. decays  Fluctuation phenomena - critical behavior: event-by-event particle comp. and spectra  Geometry of the emitting source: HBT, impact parameter via zero-degree energy flow  pp collisions in a new energy domain Photon Physics in AA collisions Pre-equilibrium Hadronization (Freeze-out) + Expansion ThermalizationQGP phase?Mixed phase direct pQCD photons decay photons direct thermal photons  Global observables: Multiplicities,  distributions  Degrees of freedom as a function of T: hadron ratios and spectra, dilepton continuum, direct thermal photons  Early state manifestation of collective effects: elliptic flow  Energy loss of partons in quark gluon plasma: jet quenching, high pt spectra, open charm and open beauty  Deconfinement: charmonium and bottonium spectroscopy  Chiral symmetry restoration: neutral to charged ratios, res. decays  Fluctuation phenomena - critical behavior: event-by-event particle comp. and spectra  Geometry of the emitting source: HBT, impact parameter via zero-degree energy flow  pp collisions in a new energy domain  Global observables: Multiplicities,  distributions  Degrees of freedom as a function of T: hadron ratios and spectra, dilepton continuum, direct thermal photons  Early state manifestation of collective effects: elliptic flow  Energy loss of partons in quark gluon plasma: jet quenching, high pt spectra, open charm and open beauty  Deconfinement: charmonium and bottonium spectroscopy  Chiral symmetry restoration: neutral to charged ratios, res. decays  Fluctuation phenomena - critical behavior: event-by-event particle comp. and spectra  Geometry of the emitting source: HBT, impact parameter via zero-degree energy flow  pp collisions in a new energy domain  Experimental advantages of Photon Measurement a single calorimeter measures photons and neutral mesons. a calorimeter identifies particles up to very high momentum  Important physics outcome on DAY-1 Most-cited single results from RHIC; 422 cited as of May 2008 Suppression of hadrons with large transverse momentum in central Au+Au collisions at s(NN)**(1/2) = 130-GeV. By PHENIX Collaboration (K. Adcox et al.). Sep pp. Published in Phys.Rev.Lett.88:022301,2002 / e-Print Archive: nucl-ex/

6 Toru Sugitate / Hiroshima Univ. / KEK page 6 Lesson-1 from RHIC Find discrepancies in Au+Au from elementary processes at high p T. The low p T feature has been known at SPS and understood as nuclear effects. KKP Kretzer data vs pQCD p+p->  0 + X hep-ex/ S.S. Adler et al. h + +h - 00

7 Toru Sugitate / Hiroshima Univ. / KEK page 7 The Jet Quenching at RHIC Suppression is very strong (R AA =0.2!) and flat up to 20 GeV/c Common suppression for  0 and  ; it is at partonic level  > 15 GeV/fm 3 ; dN g /dy > 1100 陽子+陽子衝突におけるジェット生成 高運動量粒子 クオーク ハドロン粒子多重生成 (ジェット) 高運動量粒子 ハドロン粒子多重生成 真空 原子核衝突におけるジェット抑制 Both neutral mesons and photons are essential probes for the jet quenching. R AA at higher p T reveals new features.

8 Toru Sugitate / Hiroshima Univ. / KEK page 8 Lesson-2 from RHIC Systematic error is dominant.

9 Toru Sugitate / Hiroshima Univ. / KEK page 9 Direct  via  * measurements pQCD photons decay photons thermal photons: Schematic spectrum PHENIX preliminary First direct photon excess seen at PHENIX The first promising result of direct photon measurement at low p T from low-mass electron pair analysis. Are these thermal photons? The rate is above pQCD calculation. The method can be used in p+p collisions. If it is due to thermal radiation, the data can provide the first direct measurement of the initial temperature of the matter. T 0 max ~ MeV !? T 0 ave ~ MeV !? Compare direct  and  * at LHC schematic purpose only

10 Toru Sugitate / Hiroshima Univ. / KEK page 10 Another Ion Collider at CERN  s = 14 TeV for proton + proton  s NN = 5.5 TeV for Pb + Pb ATLAS実験 ALICE実験 CMS実験 LHC - b実験  s NN at LHC = 28 x RHIC =320 x SPS = 1000 x AGS

11 Toru Sugitate / Hiroshima Univ. / KEK page 11 “Expected” Features at LHC QGP formation  X 2 T RHIC  X  RHIC  X 3-5 V FO RHIC  X 3-5  QGP RHIC dominant hard process heavy quark production X 2000 ~2% at SPS ~50% at RHIC ~98% at LHC Thermo-dynamic feature p~T~GeV Thermal photon physics High p T jet physics Heavy flavor physics

12 Toru Sugitate / Hiroshima Univ. / KEK page 12 Exp.ATLASCMSALICE NameLAr BarrelLAr EndcapECAL(EB)ECAL(EE)PHOSEMCal StructureLiquid Ar PWO + APD ~80,000ch PWO + APD ~18,000ch Pb + APD Coverage 0<|h|<1.4, 2  1.4<|h|<3.2, 2  0<|h|<1.5, 2  1.5<|h|<3.0, 2  0<|h|<0.12, 0.6  0<|h|<0.7, 0.6  Dynamic Range 20MeV-2TeVupto 4TeV5MeV-80GeV16MeV-250GeV Granularity  x  0.003x x x x x x x to 0.05x x x Res. 10%/  E  0.5% 10%/  E  0.5% 2.7%/  E  0.55% 5.7%/  E  0.55% 3.3%/  E  1.1% 7%/  E  1.5% Photon Detectors at LHC

13 Toru Sugitate / Hiroshima Univ. / KEK page 13 Simulation Studies Background photon source map Event display with AliRoot

14 Toru Sugitate / Hiroshima Univ. / KEK page 14 Lots of PCB/frame/pipes there ITS+TPC+TRD+TOF X/X 0 ~”43%”  80%

15 Toru Sugitate / Hiroshima Univ. / KEK page 15 Direct Photon Sensitivity Direct photon sensitivity (sig/noise) along two scenarios; with and without jet quenching. signal strength w/o quenching Systematic error with a TRD/TOF hole  all /  dec Thermal photons thermal  enhanced range A hole in TRD/TOF for 3 central PHOS modules, reducing X/X o =80% down to ~20%, open the thermal photon sensitive window down to 3-4 GeV.  all /  dec Thermal photon sensitive window signal strength with quenching

16 Toru Sugitate / Hiroshima Univ. / KEK page 16 PHOS Strategy in 1 st LHC year Photon physics with PHOS is very promising from the 1 st year, but There are some issues to be cleared for the success:  single warm PHOS in 2008  small acceptance; less yield, higher m  cutoff, and calibration strategy  low LY/gain; larger missing energy, higher trigger threshold, and increase non-linearity  poor m  resolution; increase sys. errors  0 &  acceptance by Takashi Iwasaki 1 st Module as of 15 May, 2008 See Yuri’s TF list * students’ working version geometrical acceptance 1 PHOS module 3 PHOS modules p T [GeV] M  [GeV]

17 Toru Sugitate / Hiroshima Univ. / KEK page 17 PHOS Strategy in 2 nd LHC year p+p at 14TeV and 1 st Pb+Pb run expected Install 3 cold PHOS modules for the 1 st Pb+Pb runs  assemble two modules by this fall  build the air-tight shells  integrate photon triggers Learn the spectrometer from p+p runs Tune the spectrometer for the best energy and spatial performances to minimize the systematic uncertainties Photon analysis in reality is not easy but fruitful output guaranteed Subgroups are now being formed in PWG4 under Yves; “You are very welcome to join the  0 team.” said by Hisa Torii, the convener. ~1000  0 in 1-2 days ~1000  0 in 1-2 days 500k  0 /10 9 events w/ warm PHOS by HT 500k  0 /10 9 events w/ warm PHOS by HT

18 Toru Sugitate / Hiroshima Univ. / KEK page 18 Conclusion ALICE is a versatile detector and PHOS is optimized for measurements of thermal photons and neutral mesons up to moderate energies. Physics scope with PHOS in the 1 st LHC years; p T spectra of neutral mesons in pp and AA  Seek new physics at the energy frontier!  Promising outcome comparing with pQCD R AA of neutral mesons & photons up to mod. p T  Promising outcome from 1 st years R AA in d+A  Indispensable info. planned in 3 rd year. Thermal photons from QGP/HG  Need good understanding of apparatus for accurate all photon and meson yields, and good AA runs pion yield from p+p in 30days by LB

19 Toru Sugitate / Hiroshima Univ. / KEK page 19 Thank you for your attention.


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