Heavy-Ion Program in CMS at the Large Hadron Collider

Heavy-Ion Program in CMS at tHeavy-Ion Program in CMS at the Large Hadron Colliderhe Large Hadron Collider

Byungsik Hong

Korea University

OutlineOutline1. Most Important results from RHIC

2. LHC & CMS

3. Heavy-ion program at LHC

4. Korean contributions to CMS so far

5. Preparation of CMS heavy-ion program in Korea

05-13-2006 KIAS Workshop on LHC 2

Motivation of HI CollisionsMotivation of HI CollisionsInvestigating the QCD prediction of a deconfined (& chiral symmetry restored) high-energy-density phase of nuclear matter

QGP is thought to have existed ten millionths of second after the Big Bang; creating the primordial matter of universe in the laboratory, Little Bang.

High-energy nuclear collisions will compress and heat the heavy nuclei so much that their individual protons and neutrons overlap and lots of pions arise, creating the Quark-Gluon Plasma (QGP)


Lattice QCDLattice QCDPhase transition is expected in a strongly interacting matter, but not so close to the Stefan-Boltzmann limit.


Relativistic Heavy-Ion Relativistic Heavy-Ion MachinesMachines

Acceleratorc.m. Energy

(GeV)Status

SIS 18

(GSI, Germany)

2A

(A=mass number)

Running

AGS

(BNL, USA)5A Finished

SIS 300

(GSI, Germany)8A

Plan to run from ~2014

SPS

(CERN, Switzerland)20A Finish soon

RHIC

(BNL, USA)200A

Has been run since 2000

LHC

(CERN, Switzerland)5500A

Plan to run from ~2007


Phases of Nuclear MatterPhases of Nuclear Matter

SIS300


Brookhaven National Lab.Brookhaven National Lab. in New Yorkin New York

Circumference: 3.83 km First collision: 2000 100A GeV Au+Au(2X1026/cm2/s) 250 GeV p+p(2X1032/cm2/s)

Relativistic Heavy Ion ColliderRelativistic Heavy Ion Collider


QGP ProbesQGP Probes

1. Expectation– quarks and quarkonium states may respond differen

tly to a plasma compared to ordinary nuclear matter

2. Hard Probes– Formed in initial collisions with high Q2

– Calculable in pQCD given • Parton structure function• Hard scattering rate• Fragmentation function q q

Hadron jet

Hadronjet


Partonic Energy Loss in QGPPartonic Energy Loss in QGP

Partons are expected to loose energy via gluon radiation in traversing a QGP(jet quenching)

Hadrons above pT > 2 GeV expected to be from jet fragmentationLook for a suppression of leading hadrons in that pT region


SuppressionSuppression

• strong suppression in π0:– decreasing with pT

– factor 6 at pT > 6 GeV/c

• similar suppression in charged hadrons– RAA slightly higher at

intermediate pT due to protons

• discrepancies in charged RAA between experiments– Glauber calculations?

– NN-reference?• better consistency

between STAR and PHENIX for central/peripheral!

PHENIX, PRL 91, 072301 (2003)


Initial vs. Final State EffectInitial vs. Final State EffectInitial state: gluon saturation?

CGC?

How to discriminate? Turn off final state d+Au collisions

Final state: parton energy loss?


Centrality DependenceCentrality Dependence

1. Dramatically different and opposite centrality evolution of Au+Au experiment from d+Au control one.

2. Jet Suppression is clearly a final state effect.

Au + Au Experiment d + Au Control Experiment

Preliminary DataFinal Data


Jet Jet CorrelatioCorrelationn

triggerPhys Rev Lett 90, 082302


Away-Side Jet Correlation at Low Away-Side Jet Correlation at Low pptt

1σ syst

2σ syst

PHENIX Preliminary


InterpretationInterpretation

Near SideFar Side

PHENIX Preliminary

Discovery of the color shockwave?Discovery of the color shockwave?


Elliptic FlowElliptic Flow

x

z

y

...))2cos(v2)cos(v21( 21

3

dyddpp

Nd

tt

Rmeas

tim

e

reaction plane

transverse plane(at midrapidity)

v2<0 v2 >0 elliptic flow

RN=(1+ v2)/(1-v2)

v1<0 v1 >0sideward flow

px = v1 pt


Anisotropic FlowAnisotropic Flowvv11, v, v22, v, v44, …, …

Sp

ect

ato

rs

Reaction plane

~-3 ~3~0

v2 = 15%v2 = 15%, v4=4%

v2 = 7%v2 = 7%, v1=+7%

v2 = 7%v2 = 7%, v1=-7%Isotropic emission

Sp

ecta

tors

X

Y

1

In-planeOut

-of-

plan

e

1.5

0.5

η∼0η∼3η∼-3

x

z


Directed Flow vDirected Flow v11

STAR, PRL92, 062301 (2004) NA49, PRC69, 034903 (2003)M. Belt-Tonjes for PHOBOS (QM04)H. Masui for PHENIX (QM04)

1. Consistent among RHIC Expts.2. Shape in forward rapidity agree with

low energy data by NA493. Elongated shape near midrapidity


vv22 vs Rapidity vs Rapidity

M.B. Tonjes for PHOBOS (QM04)

v2 is positive:v1 and v2 are in the same plane

STAR


vv22 vs Transverse Momentum vs Transverse Momentum

Quark Recombination or Coalescence?Quark Recombination or Coalescence?


Recombination ModelRecombination ModelB. Hong, C.-R. Ji, and D.-P. Min, Phys. Rev. C 73, 054901 (2006)


Summary of Present RHIC Summary of Present RHIC ResultsResults1. RHIC collisions produce more particles and energy th

an ever produced.2. Fireball is close to the condition for early universe in

energy density estimate and antiproton/proton ratio (> 0.6).

3. Jet quenching is observed with high pt single hadrons and jet correlations → rapid formation of QGP

4. Hot and dense matter behaves collectively and consistent with the quark recombination model → formation of the strongly interacting liquidlike QGP with the viscosity near zero

5. Spectra for electron and muons, and their implications for charm production.


Future of HI research Future of HI research

1. Establish that the QGP is formed via leptons.

2. Explore the energy and system size dependence for the threshold effect.

3. Spin structure function of partons, especially gluons by polarized proton collisions

4. Future Project– LHC heavy-ion collision (CMS in particular)– CBM/SIS200/GSI heavy-ion collisions for the

highest baryon density nuclear matter

RH

IC


What is LHC?What is LHC?1. Run p-p collisions f

rom 2007 - Find Higgs and Supersymmetry, etc.

2. Run Pb-Pb and other ion collisions from about 2008 - Find QGP and study the detailed properties.


Cosmic TimelineCosmic TimelineTaken from Scientific American (May 06)Taken from Scientific American (May 06)


CMS (Compact Muon Solenoid)CMS (Compact Muon Solenoid)


Tracking with Tracking with heavy-ion eventsheavy-ion events

pT/

p T (%

) |η| < 0.7

FakesE

ffic

ienc

y (%

)

dN/dy

pT > 1GeV

pT > 3GeV

pT (GeV)

(c

m)

Impact parameter resolutionImpact parameter resolution

• z

• r

Fakes

Eff

icie

ncy

(%)

pT (GeV)


TOTEM T2

BCM Sensor CarriageScintillators atz=10.5m

IP

TOTEM T1

BCM Sensors

ZDC @ 140 m

CASTOR

Lumi monitor

Hermetic calorimetry up to ||<7 plus zero degree neutral energy. T1 and T2 are multiplicity detectors.Physics: Centrality, Low-x, Limiting fragmentation, strangelets, DCC, etc.

Forward DetectorsForward Detectors


ET for 3<||<5

Collision GeometryCollision GeometryE

T (G

eV)

b (fm)

Assume = 0.1 radians

x

z

y


Expected Expected NNchch ?

HIJING vs

ion extrapolat RHICby

000,7200,1/ dydNch


Kinematic Range by LHCKinematic Range by LHC

J/ψ

Z0

BRAHMSBRAHMSP

HE

NIX

PH

EN

IX

LHCLHCε ~ 50 GeV/fm3

Low xHigh M High Pt

JetsQuarkoniaPhotonsZ0, etc.

by


Abundant QuarkoniaAbundant Quarkonia

J/ψ

Large production cross section→ should be enough to observe different melting points

of 3 states.


Quarkonia and QGP Quarkonia and QGP Ref) H. Satz, hep-ph/0512217

larger

smaller


Quarkonia in CMSQuarkonia in CMS

J/ family

Expect ~24k J/ψ and ~ 18/5/3 k ,’,’’

for one month with L=1027cm-2s-1

and 50% efficiency

σM = 50 MeV

Coverage in central rapidity region

- -

+ +


Abundant JetAbundant JetLarge jet cross section

•Full jet reconstruction: jet-jet, jet-, jet-Z0 correlations

•Study in medium modifications


Fragmentation of 100 GeV Jets Fragmentation of 100 GeV Jets

Precision tracking out to high

momenta will give detailed

information on modification of the jet by the medium

axis

pT jet

pT relative to thrust axis

Momentum fraction z along thrust axis


Forward Region of CMS

Korea

Italy

Korea in CMSKorea in CMS Total Area of Endcap RPC ~1,400 m2


Resistive Plate ChamberResistive Plate Chamber

Final Gas mixture used in all tests95.5% Freon 3.5% Isobutane 0.3% SF6 + RH 50%

GapMechanics


History of the Korean RPCHistory of the Korean RPC1. Fundamental studies to develop the Endcap RPCs (1997 - )

1) CERN beam test by using high intensity muon beam and 20 Ci 137Cs2) Cosmic muon tests (Korea Univ.) 3) Study of RPC pulses and simulations 4) Long term aging study for linseed oiled RPC

2. Design of double gap RPCs for the Endcap Region (2000 – 2003)1) Chamber designs 2) Services for HV, LV, gas, electronics on the chamber level

3. Detector manufacturing facilities (2000 – 2003) 1) Gap and chamber production facilities 2) Gaps and chamber testing facilities for the quality controls

4. Mass production of the Endcap RPC (2004 - )


Endcap RPCEndcap RPC1. Function : L1 muon triggers 2 wings (RE+, RE-)

4 stations (RE1, RE2, RE3, RE4)

Pseudo rapidity covering:

0.9 < η < 2.1(1.6)

η segmentations : 10 (6)

2. Total # of RPCs : 756 (432)

Total # of FEBs : 2,268 (1,296)

Total # of channels : 85,248 (41,472)

3. By September 2006,

the gap production in 0.9 < η < 1.6

will be completed for the

first operation of the CMS detector.


Korean Endcap RPCKorean Endcap RPC

Characteristics

CMS Requiremen

tsTest Results

Time Resolution < 3 nsec < 1.5 nsec

Efficiency > 95 % > 95 %

Rate Capability > 1 kHz/cm2 > 1 kHz/cm2

Noise Rate < 15 Hz/cm2 < 10 Hz/cm2

Plateau Region > 300 V > 400 V

Summary of the Performance


18 RE1/2s have been installed on CMS in last 2 weeks

A RE1/2 is mated to CSC before installation

Installation of the very 1st RE1/2+CSC module

1st RE1/2 installed on CMS

CSC

RE1/2


Participation of the Korean Participation of the Korean Heavy-Ion Group in CMSHeavy-Ion Group in CMS

1. Korea University (B. Hong and K.S. Sim)– Important role in the endcap RPC production since 1997– Preparing the computing facility for MC simulation and d

ata analysis

2. Konkuk University (J.T. Rhee)– Important role in the endcap RPC production since 1997

3. City University of Seoul (I.C. Park)– Will use existing computing facility for MC simulation and

data analysis

4. Pusan National University (I.K. Yoo)5. Yonsei University (J.H. Kang)6.6. All major HI institutions in Korea will participatAll major HI institutions in Korea will participat

e in the CMS Heavy-Ion program.e in the CMS Heavy-Ion program.

CM

S 참

여를

결정

한 순

서


ConclusionsConclusions

1. RHIC has produced a lot of exciting new results on the quark-gluon matter in extreme conditions.

2. We look forward to seeing even more exciting results in heavy-ion collisions at LHC.

– New energy frontier: √s ~1.2 PeV for a Pb-Pb collision event

3. Korean Heavy-Ion group has contributed a lot already on the construction of the CMS endcap RPC system.

4. Korean Heavy-Ion group is preparing the computing farm for the CMS MC generation and data analysis.

5. All major institutions will participate in the CMS heavy-ion program.

Heavy-Ion Program in CMS at the Large Hadron Collider

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