1Shine and Shadow
from Quark Gluon Plasma
Hisayuki Torii (Hiroshima Univ. Japan)
7th Heavy Ion Pub at Osaka Univ.
2009/11/17

Heavy Ion Pub 2009/11/20 H.Torii(v) to produce light(n) the brightness that something has when light shines on it[by longman dictionary]2

Heavy Ion Pub 2009/11/20 H.Torii

By NASA’s Extreme ultraviolet Imaging Telescope (EIT) over the course of 6days from 27/6/2005
http://www.boston.com/bigpicture/2008/10/the_sun.html

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From Hirano-san’s web page.

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Shining Heavy Ion Collisions
Hadronization(Freeze-out) +Expansion

Mixed phase

Thermalization
QGP phase?

Pre-equilibrium

Thermal Photon

Jet+Medium

Prompt Photon

Thermal Photon (QGP)
Thermal Photon (HG)

Jet-Photon Conversion
Jet-Bremsstrahlung (QGP)

Compton/Annihillation
Fragmentation

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Schematic Spectrum in A+A
Decay photons

thermal: e− E γ /T

1

1 - 10GeV/chard npT:

Thermal Photon

Jet+Medium

Prompt Photon

Thermal Photon (QGP)
Thermal Photon (HG)

Jet-Photon Conversion
Jet-Bremsstrahlung (QGP)

Compton/Annihillation
Fragmentation+ photons from hadron decay
Photons are collective probes for various expansion stages of the hot matter

Heavy Ion Pub 2009/11/20 H.Torii(1) High pT Meson Identification• quark flavor dependent suppression?

▫ Interesting behavior of nuclear modification for various
mesons and hadrons has been reported at RHIC

Photon from meson decay is a good tool ofmeson identification experimentally at high7/11
pT.

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8(2) Universality• Direct photon production inp+p or p+p-bar shows
universality

σ=( s ) × F (x )−nT▫ Consistency with pQCD
prediction▫ Good probe for initial parton
distribution

Any enhancement
above the scaling (orpQCD calculation) canbe new physics
8Heavy Ion Pub 2009/11/20 H.Torii

9(3) Temperature Sensor
RHIC

LHC Prediction

Indirect Photon Method

First Direct Photon Excess seen at low pTTemperature from thermal photon
measurement results in 300-500MeV

Photon excess is predicted
at pT<10GeVHigh multiplicity (~12000 h±/η)Wide dynamic Range (0.1-80GeV)
Advantage at LHC• Higher temperature, Longer QGP lifetime, Larger background photon suppression

Heavy Ion Pub 2009/11/20 H.Torii

10(3) Temperature Sensor
RHICIn-direct (Internal Conversion) method

First Direct Photon Excess seen at low
pT by In-direct measurement at RHIC

For Direct Measurement

1. Higher Temperature Î High Energy=LHC
2. Improved Experimental Calorimeter

LHC with precise calorimeter andwide energy coverage (down to 0.1GeV)Heavy Ion Pub 2009/11/20 H.Torii

11(4) Transparency
Single Hadron

DihadronGamma-hadronsmall zT

SKIN Effect

H.Z.Zhang et al. PRL98(2007)212301 + slides at ATHIC08

Probe to the center of hot matter
Ephoton = EJet

Heavy Ion Pub 2009/11/20 H.Torii(5) Parton Identification• Naively, gluon jet is quenched more than quark jet▫ Strong Interaction Color Factor C(A) : C(F) = 3 : 4/3• Comparison between gluon and quarkÎ Extream test of quenching effectSingle/Di-Hadrons/Jets

PYTHIAPi0 at 14TeV

Photon-Hadrons/Jets

PYTHIA 5.5TeV
PYTHIA 5.5TeV

Gluon Dominant

Quark Dominant

Quark jet identification

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Heavy Ion Pub 2009/11/20 H.Torii(n) A dark shape that someone or something makes on asurface when they are between that surface and the light[by longman dictionary]13

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日本一大きな影

Largest shadow in Japan!!!
Taken from the top of highest mountain in Japan, Mt. Fuji.
Taken by H.T. in 1996 summer.

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世界一高性能の(GeV光子)電磁カロリーメータ

Finest GeV-photon calorimeter in the world15

Heavy Ion Pub 2009/11/20 H.Torii

L-Shell
K-ShellElectro-Magnetic Interaction
photonPhoton lose energy or convert into electron by“Photoelectron absorption ( γ+atom Æ ion+e-)”“Compton ( γ+e- Æ γ+e-)” process

2Me

Pair creation dominates at > 10MeV (for Pb)(cut of > 2Me)

Pair production probability after X0[cm] length is 1-e-7/9=54%.

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Electro-Magnetic Interaction
Critical Energy

electron/positron

Energy loss by bremsstrahlung is characterized by “Radiation Length”(in the high energy limit where the ionization loss can be neglected)

dE/E = - dx/X0 Î <E> = E0*exp(-x/X0)

Critical Energy (Ec) : “Ionization loss = Bremsstrahlung loss”
Ec=6.9MeV for Pb

EC ≈ 580 MeV Z

If the energy is less than Ec, the e-/e+ lost17

Heavy Ion Pub 2009/11/20 H.Torii

Electro-magnetic Showerphoton

1.
2.
3.
4.

One pair creation on average after X0, Ee+≅ Ee- ≅E0/2
e+ and e- radiate one photon after X0.
e+ and e- deposit “ionization energy” through matter
Continue 1-3 until Ee+≅ Ee- is below the critical energy(Ec)▫
Electron <Ec stop after ~0.5cm(for Pb) due to ionization loss▫
Number of shower particles (2d) increases exponentially withdepth(d)18Heavy Ion Pub 2009/11/20 H.Torii

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MeV/2cm2

In real life…

100GeV
photonHeavy Ion Pub 2009/11/20 H.Torii

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MeV/2cm2

How to Collect the Deposited Energy?

• Collect Ionization energy loss (or Cerenkov light) by e+ and e• Two type
▫ Inhomogeneous or Homogeneousx Inhomogeneousx Sandwich with “heavy material” + “ionization energy loss detector”
x Homogeneousx “heavy material” itself is “ionization energy loss detector”

Heavy Ion Pub 2009/11/20 H.Torii

21Inhomogeneous Calorimeter• Inhomogeneous : Sampling Calorimeter▫ Metal + “ionization energy loss detector”
x Some exception is to utilize Cerenkov light emmission.

▫ Disadvantage: “ionization energy loss” in metal is not detectable.
▫ Three types for “ionization energy loss detector”
x Solid or Liquid or Gas
Solid : Organic scintillator

Solid(Silicon), Liquid( ex. LiAr),
Gas(Ar+Co2, etc)

Heavy Ion Pub 2009/11/20 H.Torii

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Example of Inhomogeneous TypePHENIX PbSc Calorimeter

Shashlik type calorimeter

シシケバブ：四角形の肉を串に刺して焼いたトルコ料理

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Example of Inhomogeneous : PHENIX PbSc
•Organic Scintillator•5cm x 5cm x 4mm(thickness)•Aluminum vapor edge on four edge,
one cornor is remained open formonitoring light input.
•Scintillation light are gathered throughwave length shifter fibers and collected
into a PMT.

Size(cm x cm)
Depth(cm)Number of towers
Sampling fraction
η cov.
φ cov.
η/mod
φ /modX0
Moli ère Radius

PbSc
5.52 x 5.52
37.515552~ 20%
0.7
90+45deg
0.011
0.011
18~ 3cmPbSc sector 2.0m x 4.0m

Heavy Ion Pub 2009/11/20 H.ToriiHomogeneous Type• Homogeneous : Crystal Calorimeter▫ Crystal itself is “ionization energy loss detector”
x NaI, CsI, Bi4G, GSO, BGO, PbWO4, LYSO
x Scintillation radiation▫ Some exception is a glass (PbGl) as a Cerenkov
radiator

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Crystal Development• ~100 years development

Slide by Ren-Yuan Zhu at CALOR2008

M.J.Weber, J.Lumin 100(2002)35

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18cm

CSP preamplifier(FET based, 2x2cm)• PbWO4 Crystal

2.2x2.2cm2

Example of Homogeneous Type: PHOS

PbW04 crystal

APD(5x5mm)• Avalanche Photo Diode(APD) + Preamp▫ 22 x 22 x 180 mm3, ~20,000yen/crystal– Hamamatsu Co.,
3~7,000yen/APD+~8,000yen/Preamp▫ ~2cm Moliere Radius, 20X0, 8.2g/cm– S8148/S8664-55▫ Scintillation light (400nm-500nm)– High Q.E.(60%-80%)▫ Operation at -25deg Æ 25ns
– Low noise and capacitancedecay,230pe/MeV– Thin photo-sensor▫ With APD acceptance:– Operational at low temperature and4.5pe/MeV@-25deg, 1.45pe/MeV@+20deg.
in magnetic field▫ North Crystal Co. Apatity in Russia

Heavy Ion Pub 2009/11/20 H.Torii

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Example of Homogenous Type : PHOS
• PbWO4 Crystal▫ Fast Signal (~nsec)▫ Operation at -25deg Î 3 times
large scintillation photon▫ Smaller Moliere Radius (2cm)Î Good 2 photon Separation

2x2cm25mmx5mm
Avalanche Photo Diode (APD)• High Q.E.(60%-80%)• Thin photo-sensor• Operational in magnetic
field

5x5mm
APD: Hamamatsu S8148/S8664-55

Preamplifier

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Detector Performance Requirement(1)< Linearity >1GeVphoton10GeV
photonLarger energy photon
produces deeper shower

Uniform detection andcollection of the depositedenergy plays an important rolein detector performance,
especially energy measurement
linearity and energy resolution
at high pT.
<keyword> isUniformity
100GeV
photonHeavy Ion Pub 2009/11/20 H.Torii

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Detector Performance Requirement(2)<Energy Resolution>

100GeV
photonShower Leackage<keyword> isEnough Size
From deposited energy into detectable object
ex. Number of scintillation photon“The detectable object carry out part of all energy”
Statistical fluctuation Î Energy resolution ∝1/√E<keyword> is

Efficient “ionization loss” detector
ex. large light emission, good efficiency, good sampling ratio

PHENIX PbSc
Energy Resolution

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Detector Performance Requirement(3)fluctuation<Position Resolution>

100GeV
photonfluctuation

Center of gravity is the measurement of theincident position and angle, which are affected by
the lateral and longitudinal fluctuation.
<keyword> is

Small Radiation LengthÎCompact shower == small fluctuation
Measurement of fluctuation is another keyword.

ALICE PHOS
Lateral position Res.

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Heavy Ion Pub 2009/11/20 H.Torii

Heavy Ion Collisions at LHC
p+p
Pb+Pb
Energy√s =14 TeV√sNN=5.5 TeV/A
LHC = 28 x RHIC =320 x SPS = 1000 x AGS
ＣＭＳ実験

ＬＨＣ-ｂ実験
ＡＴＬＡＳ実験
ＡＬＩＣＥ実験

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Heavy Ion Pub 2009/11/20 H.Torii

ALICE at Point-2

The ALICE Experiment

30 countries, 97 institutions, ~1,015 members as of Jan.2007

1000th ALICE member

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Detector:Size: 16 x 26 meters
Weight: 10,000 tons

Collaboration:> 1000 Members> 100 Institutes> 30 countries

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Heavy Ion Pub 2009/11/20 H.Torii

ALICE Installation Status in 2009
EMCAL
Complete:
ITS, TPC, TOF, HMPID,FMD, T0, V0, ZDC,
Muon arm, Acorde
PMD , PHOS(3/5), DAQ
Partial installation:
7/18 TRD
4/12 EMCAL~ 60% HLTPHOS35

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Photon Detectors at LHC

Exp.

Name

Structure

ATLAS
LAr Barrel

CMS

LAr Endcap

Liquid Ar

Coverage0<|η|<1.4,2π

1.4<|η|<3.2,

GranularityΔηxΔϕ

0.003x0.100
0.025x0.025
0.025x0.050

0.025x0.100
0.025x0.025
0.025x0.050

Res.

2π

ECAL(EB)

ECAL(EE)

PWO + APD

ALICEPHOS

EMCAL

PWO + APD

Pb + APD

0.0143x0.0143

Cover Jet Size|η|<0.12,|η|<0.7,0.6π
0.6π
Two Separation0<|η|<1.5,2π

1.5<|η|<3.0,2π

0.0174x0.0174

0.0174x0.0174
to 0.05x0.05

0.004x0.004

5.7%/√E⊕
0.55%

Cover Low Energy
3.3%/√E⊕
7%/√E⊕1.5%
1.1%

10%/√E⊕ 10%/√E⊕ 2.7%/√E⊕
0.5%
0.5%
0.55%

PHOS for low energy photon, EMCAL for jet energy

Heavy Ion Pub 2009/11/20 H.Torii

PHOS CalorimeterPbWO4 Crystal▫ Fast Signal (~nsec)▫ Operation at -25deg▫ Smaller Moliere Radius (2cm)Î Good 2 photon Separation

Combination of recent hightechnology.

• Total 17920 channel
PbW04 crystal

100deg -0.12<η<0.12

Avalanche Photo Diode (APD)– High Q.E.(60%-80%)– Thin photo-sensor– Operational in magnetic
field
2x2cm
APD: Hamamatsu
S8148/S8664-55
5x5mm~12.5ton

3/5 modules for 2009 runs
Under cosmic commissioning
約７m

37Heavy Ion Pub 2009/11/20 H.Torii38

EMCAL Calorimeter
Pb/Sc Shashlik
77 x (1.44mm Pb + 1.76mm Sci.)
6.0x6.0x24.6cm3 active vol.

Approved 12/2008• 10+2/3 Super Modules
110deg -0.7<η<0.7

Avalanche Photo Diode (APD)– High Q.E.(60%-80%)– Thin photo-sensor– Operational in magnetic
field
2x2cm
APD: Hamamatsu
S8148/S8664-55
5x5mm~85tonFour SM for 2009 run
Complete for 2011
Under cosmic commissioning

Heavy Ion Pub 2009/11/20 H.Torii

Photon Spectrometer (PHOS)

High-granularity, high-resolution EM calorimeter▫ 64x56x5 PbWO4 crystals readout with APD/CSP▫ Precise measurement of photons and neutral mesons▫ level-0 and level-1 trigger▫ Partial installation 3/5 as of 2009

64x56 matrix

HUST & CCNU

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PHOS Calorimeter~3% fluctuation termis best value in theworld for the working
calorimeter.

Well controlled performance (energy resolution)from 150MeV to 200GeVHeavy Ion Pub 2009/11/20 H.Torii

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Physics Potential: Neutral Pion in p+p
WA98(CERN)PHENIX(BNL)

ALICE(CERN)
π0 (E=5-6GeV)(π-+12CÆπ0+X)

Pb+Pb 13GeV
nucl-ex/0108006

p+p 200GeV run2

13MeV width of π0@1GeV/cp+p 14TeVGEANT simulation

5-6MeV

Improvement of particle identification compared to the other HI exp.

Heavy Ion Pub 2009/11/20 H.Torii

The Challenge in RHI Experiments

Pb+Pb at √sNN = 5.5 TeV at ALICE

p+p at √s = 14 TeV at ALICE42

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Physics Potential:
Neutral
PioninPb+Pb0• Expected π peak in central Pb+Pb HIJING
pT = 3 GeV/cpT = 4 GeV/cpT = 5 GeV/cpT = 6 GeV/cpT = 7 GeV/cpT = 8 GeV/cpT = 9 GeV/cw/o γID

pT = 10 GeV/cw/o γID• Enough large significance for π0 .

▫ more species (η, ω, K0s) under study
See talk (14th/Oct, Session BB-11) by Kenta Shigaki

Heavy Ion Pub 2009/11/20 H.Torii

Physics Potential: LHC First Pb+Pb Year

RHIC 10 years and LHC 1st HI year44

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Physics Potential: Thermal Photon• expected signal/background ratio▫ 4 ~ 10 % (3 GeV/c) – 25 ~ 50 % (10 GeV/c)• expected systematic error with ALICE/PHOS▫ 8.9 % (2 GeV/c) – 5.7 % (10 GeV/c)

Without Jet Quenching

Systematic error in thermal photon measurement is well smaller
than statistic error at the pT>3GeV/cHeavy Ion Pub 2009/11/20 H.Torii

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Current LHC RUN Plan
CERN DG message in Feb. 2009 from the Chamonix workshop:“… foresees first beams in the LHC at the end of Sept. this year, withcollisions following in late Oct. A short technical stop over Xmas
period. Then run through to autumn next year, ensuring data … firstnew physics analyses … the possible collisions of lead ions in 2010.”Prof. Rolf-Dieter Heuer, DG

DG message in Feb. 2000
that
“The challenge now passes
to RHIC and later to
CERN's Large HadronCollider."• 2009:• 1 month commissioning• 2010:• 1 month pilot & commissioning• 3 month 3.5 TeV• 1 month step-up (to be decided)• 5 month 4 - 5 TeV• 1 month ionsHeavy Ion Pub 2009/11/20 H.Torii

Let’s follow rabbit to wonderland!!!

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Thank you

I’m here!!!

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