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CMS Experiment at CERN LHC

Young-Il ChoiSungkyunkwan University

(Hanyang Univ. 08.9.24 )

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Prof. Young-Il Choi (Sungkyunkwan University)

EDUCATION:- Ph. D. in Physics, (1982-1986) 1986 University of Pittsburgh, Pittsburgh, PA, USA- M. S. in Physics, (1980-1982) 1982 University of Pittsburgh, Pittsburgh, PA, USA- B. S. in Physics, (1974-1979) 1979 Seoul National University, Seoul, Korea

CAREER: - Professor (1997 - ) Sungkyunkwan University- Associate Professor (1992 - 1997) Sungkyunkwan University- Research Scientist (1989 - 1992) Purdue University, IN, USA- Research Associate (1986 - 1989) Purdue University, IN, USA

RESEARCH:- CMS Experiment at CERN, Switzerland (2000 – 2007 – )

- RENO Experiment, Korea (2006 – )- Super Kamiokande Experiment , Japan (2002 - )- BELLE Experiment at KEK, Japan (1997 - )- ALEPH Experiment at CERN LEP, Switzerland (1995 - 1997)- EOS-TPC Experiment at LBL HISS, USA (1989 - 1996)- E735(Quark-Gluon Plasma) at FNAL Tevatron, USA (1986 - 1992)- AFS(E808) Experiment at CERN ISR, Switzerland (1982 - 1986)

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Information for K-CMS LHC experimentInformation for K-CMS LHC experiment

http://public.web.cern.chhttp://cms.cern.ch

http//www.cms-kr.orghttp//www.cms-kr.orgPhysics & High TechnologyPhysics & High Technology 2008.052008.05

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Overview

CERN & LHC CMS Detector Korea-Korea-CMS ExperimentCMS Experiment GroupGroup Particle Physics TheoryParticle Physics Theory Life at CERN

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CERN & LHC

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CERN Member StatesCERN Member States

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CERN CMS ExperimentCERN CMS Experiment

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CERN SiteCERN Site

LHC

CERN Site (Meyrin)CERN Site (Meyrin)

SPS

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LHC DetectorsLHC Detectors

B-physicsCP Violation

Heavy IonsQuark-gluon plasma

General-purposeHiggsSUSY??

General-purposeHiggsSUSY

??

TOTEM

LHCf

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Collisions at the Large Hadron ColliderCollisions at the Large Hadron Collider

Bunch Crossing

4x107Hz

7x1012 eV Beam Energy 1034 cm-2 s-1 Luminosity 2835 Bunches/Beam 1011 Protons/Bunch

7 TeV Proton

Proton

colliding beams

Proton Collisions 109 Hz

Parton Collisions

New Particle Production 105 Hz (Higgs, SUSY, ....)

p pH

µ+

µ-

µ+

µ-

Z

Zp p

e- e

q

q

q

q

1

-

g~

~

20~

q~

1 0~

7.5 m (25 ns)

- Injection test very successful

LHC timelineLHC timeline

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1984 Workshop on a Large Hadron Collider in the LEP tunnel, Lausanne

1987 Rubbia “Long-Range Planning Committee” recommends Large Hadron Collider as the right choice for CERN’s future

1990 ECFA LHC Workshop, Aachen

1992 General Meeting on LHC Physics and Detectors, Evian les Bains

1993 Letters of Intent (ATLAS and CMS selected by LHCC)

1994 Technical Proposals Approved

1996 Approval to move to Construction (ceiling of 475 MCHF)

1998 Memorandum of Understanding for Construction Signed

1998 Construction Begins (after approval of Technical Design Reports)

2000 LEP closes, LHC installation starts

2004 Last experimental cavern (CMS) completed

2008 LHC and experiments ready for first beam (Sep.10)

LHC inauguration Ceremony (Oct. 21)

p + p collisions (?)

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The CMS CollaborationThe CMS Collaboration

CMS Collaboration

USA

Austria

Belgium

Finland

France

Germany

Greece

Hungary

Italy

Poland

Portugal

Slovakia

Spain

CERN

Switzerland

UK

37 Countries184 Institutes2930 Scientists and Engineers

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CMS Detector

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CMS – Compact Muon SolenoidCMS – Compact Muon Solenoid

-Total weight : 12,500 t-Overall diameter : 15 m-Overall length : 21.6 m-Magnetic field : 4 Tesla

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CMS Detector

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Transverse View of CMSTransverse View of CMS

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““Swivelling the coil”Swivelling the coil”

Coil is constructed vertically but needs to be horizontal!

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Standing in the coil – at 100K!Standing in the coil – at 100K!

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The The ““Gothic Cathedrals of the 21Gothic Cathedrals of the 21stst Century Century””CMS detector 100m underground

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Particle DetectorsParticle Detectors• Cannot directly “see” the collisions/decays

– Interaction rate is too high– Lifetimes of particles are too small

Even moving at the speed of light, some particles (e.g. Higgs) may only travel a few mm (or less)

• Must infer what happened by observing long-lived particles– Need to identify the visible long-lived particles (e, p, π, μ

etc) Measure their momenta

Energy(speed)

– Infer the presence of neutrinos and other invisible particles

Conservation laws – measure missing energy

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Particle Momentum MeasurementParticle Momentum Measurement

• Electrically charged particles moving in a magnetic field curve

• Radius of curvature is related to the particle momentum R = p/0.3B

• Should not disturb the passage of the particles

• Low-mass detectors sensitive to the passage of charged particles

• Many layers – join the dots!

• E.g. CMS silicon tracker ElectronIn CMS

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Energy Measurement - CalorimetersEnergy Measurement - Calorimeters

• Idea is to “stop” the particles and measure energy deposit

• Particles stop via energy loss processes that produce a “shower” of many charged and neutral particles –

pair-production, bremsstrahlung etc.

• Detector can be to measure either hadrons or electrons/photons

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The CMS Muon SystemThe CMS Muon System

• The Higgs decay into ZZ to 4 is preferred for Higgs masses > 160 GeV. Coverage to || < 2.5 is required ( > 6 degrees)

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Particle interactions in detectorsParticle interactions in detectors

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PuzzlePuzzle

Find 4 straight tracks.

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AnswerAnswer

Make a “cut” on theTransverse momentumOf the tracks: pT>2 GeV

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Korea-CMS Experiment Group

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Status of Korea-CMS Experiment Status of Korea-CMS Experiment GroupGroup

-1994 CMS Ex-Spokesperson Dr. Della Negra contacted Korean groups < Kangnung, KNU, KU, SKKU >-1997 KU S.K. Park research fund(190MW 3yrs) from MoST: KODEL < KNU, KU joined CMS experiment >-1999 KU-CERN CMS MoU(Forward RPC detector construction)-2000 KU S.K. Park research fund (410MW 5yrs) 13 Universities(Kangwon, KNU, Konkuk, KU, Dongshin, Seonam, SNU, Seoul Education, SKKU, Wonkwang, CNU Jeju, Chungbuk) 5 Subgroups: Single Gap Production(K.S. Shim), Assemblage(J.T. Rhee), Network(S.B. Kim), Power Supply(Y.I. Choi), Magnet(S.K. Park) < 11 Universities joined CMS experiment >-2002 <KNU, Dongshin, SNU, SKKU, CNU> withdrawed from the KU RPC Construction Project-2003 KNU(SRC)-CERN CMS MoU(0.5MCHF DAQ PC Farm Construction) -2006 MoST-CERN MoU (payed CMS M&O Cat. A for 2005-2007 only)-2007 MoST Korea-CERN cooperation: organized Korea-CMS experiment group-2008 UoS joined CMS experiment in June.

* CMS requires about 0.2MCHF/institute contribution to join CMS newly.

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[MEST][MEST] Korea-CERN Cooperation ProjectKorea-CERN Cooperation Project

□ Organization

MEST

| --- Steering Committee

KICOS

|

ALICE CMS LCG (ALICE, CMS)

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18 Prof.s applied for Korea-CMS research fund(07.3.23)18 Prof.s applied for Korea-CMS research fund(07.3.23)

• S.J. Hong(Gacheon-KU) 14.30 MWon• S.K. Oh(Konkuk-KNU) 75.00• J.T. Lee(Konkuk) 43.10• *K.N. Kim(KNU) 1,74.60• D.H. Kim(KNU) 1,01.44• D.C. Son(KNU) 1,71.64• S.K. Park(KU) 2,12.92• K.S. Shim(KU) 1,07.00• E.I. Won(KU) 86.50• B.S. Hong(KU) 85.00• K.K. Joo(SNU) 48.00• I.K. Parc(UoS-KU) 40.00• I.T. Yu(SKKU) 30.70• S.Y. Choi(SKKU) 74.80• Y.I. Choi(SKKU) 53.30• J.Y. Kim(CNNU) 53.50• E.J. Kim(CPNU-KNU) 26.10• *S.K. Choi(KSNU 11.60

Total 1,409.50 MWon

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Research Fund for 2007: Research Fund for 2007: 800MW800MW

• SKKU: 565MW - Stipends - Travel expenses - Computers & Material expenses - Center operational expenses - Overhead

• CERN: 235MW - Staying expenses: Ph.D 4000CHF/M, Students 2500CHF/M (1CHF = 800W) - Computers & Material expenses - Apartment rent, car rent

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Korea-CMS group members(60 persons)Korea-CMS group members(60 persons)• Team-1 Lepton(muon) group - 교수 : 김동희 ( 경북대 ), 원은일 ( 고대 ), 유인태 , 최수용 ( 팀장 ), 최영일 ( 성대 ) - 연구원 : 공대정 , 김지은 , 김현수 , 박차원 , 서현관 , 서준석 , 주경광 - 대학원생 : 고정환 , 권정택 , 김장호 , 이종석 , 정호연 , 아즈말 , 미안

• Team-2 RPC group - 교수 : 박성근 ( 팀장 )( 고대 ), 이준택 ( 건대 ), 홍성종 ( 가천의대 ) - 연구원 : 이경세 , 장현자 , 자밀 - 기술자 : 정영군 , 손광재 , 강민호 - 대학원생 : 안성환 , 김태정 , 임정구

• Team-3 DAQ & Analysis group - 교수 : 김귀년 ( 팀장 ), 손동철 ( 경북대 ), 오선근 ( 건대 ), 김재률 ( 전남대 ) - 연구원 : 김경숙 , 김진철 , 노상률 , 이만우 , 정진혁 , 박향규 , 함승우 - 대학원생 : 송상현 , 안상언 , 서지원 , 허애영 , 유스포브

• Team-4 Heavy Ion group - 교수 : 김은주 ( 전북대 ), 박인규 ( 팀장 )( 서울시립대 ), 심광숙 , 홍병식 ( 고대 ) - 연구원 : 김근범 , 박진우 , 김유상 , Sood Gopika - 대학원생 : 김지현 , 김현철 , 문동호 , 심현하 , 한가람

* Anyone can join freely.

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Korea-CMS groupKorea-CMS group operationoperation

• Web site for K-CMS group• K-CMS group workshop: twice a year • (Mini-) workshops with theorists: twice or more• Annual evaluation for research activity:

(evaluate the results quantitatively)

=> M&O Cat. A. 12 selection (Authorship)

=> Research Fund

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Particle Physics

Theory

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Matter and Force ParticlesMatter and Force Particles

Gluons (8)

Quarks

MesonsBaryons Nuclei

Graviton ? Bosons (W,Z)

AtomsLightChemistryElectronics

Solar systemGalaxiesBlack holes

Neutron decayBeta radioactivityNeutrino interactionsBurning of the sun

Strong

Photon

Gravitational Weak

The particle drawings are simple artistic representations

Electromagnetic

Tau

Muon

Electron

TauNeutrino

MuonNeutrino

ElectronNeutrino

-1

-1

-1

0

0

0

Bottom

Strange

Down

Top

Charm

Up

2/3

2/3

2/3

-1/3

-1/3

-1/3

each quark: R, B, G 3 colours

QuarksElectric Charge

LeptonsElectric Charge

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The Standard ModelThe Standard Model

Where is Gravity?

Me ~ 0.5 MeVM ~ 0Mt ~ 175,000 MeV!

M = 0MZ ~ 100,000 MeV

Why ?

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Unification of fundamental forcesUnification of fundamental forces

Quantum Gravity

Super Unification

Grand Unification

Electroweak Model

QED

Weak Force

Nuclear Force

Electricity

Magnetism

Maxwell

Short range

Fermi

QCD

Long range

Short range

Terrestrial Gravity

Celestial Gravity

Einstein, NewtonGalilei

Kepler

Long range

?

Universal Gravitation

Electro magnetism

Weak TheoryStandard

model

Theories: STRINGS? RELATIVISTIC/QUANTUM CLASSICAL

SU

SY

?

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Origin of mass and the Higgs mechanismOrigin of mass and the Higgs mechanism

Simplest theory – all particles are massless !!

A field pervades the universe

Particles interacting with this field acquire mass – stronger the interaction larger the mass

The field is a quantum field – the quantum is the Higgs boson

Finding the Higgs establishes the presence of the field

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If MIf MH H < 160 GeV use H --> ZZ --> 4e or 4< 160 GeV use H --> ZZ --> 4e or 4

Fully active crystals are the best resolution possible needed for 2 photon decays of the Higgs.

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Grand Unified TheoriesGrand Unified Theories• Perhaps the strong and electroweak forces are related. In that case leptons and quarks

would make transitions and p would be unstable. The unification mass scale of a GUT must be large enough so that the decay rate for p is < the rate limit set by experiment.

• The coupling constants "run" in quantum field theories due to vacuum fluctuations. For example, in EM the e charge is shielded by virtual fluctuations into e+e- pairs on a distance scale set by, e ~ 1/me. Thus increases as M decreases,(0) = 1/137, (MZ) = 1/128.

100

105

1010

1015

0

10

20

30

40

50

60

70Evolution of Coupling Constants in the SM

Mass(GeV)

1/

3

2

1

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SUSY and Evolution of SUSY and Evolution of

100

105

1010

1015

1020

0

10

20

30

40

50

60

70Evolution of Coupling Constants in SUSY

Mass(GeV)

1/

3

2

1

It is impossible to maintain the big gap between the Higgs mass scale and the GUT mass scale in the presence of quantum radiative corrections. One way to restore the gap is to postulate a relationship between fermions and bosons. Each SM particle has a supersymmetric (SUSY) partner with spin 1/2 difference. If the mass of the SUSY partners is ~ 1 TeV, then the GUT unification is good - at 1016 GeV

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Unanswered questions in Particle PhysicsUnanswered questions in Particle Physics

a. Can gravity be included in a theory with the other three interactions ?

b. What is the origin of mass? LHC

c. How many space-time dimensions do we live in ?

d. Are the particles fundamental or do they possess structure ?

e. Why is the charge on the electron equal and opposite to that on the proton?

f. Why are there three generations of quark and lepton ?

g. Why is there overwhelmingly more matter than anti-matter in the Universe ?

h. Are protons unstable ?

i. What is the nature of the dark matter that pervades our galaxy ?

j. Are there new states of matter at exceedingly high density and temperature?

k. Do the neutrinos have mass, and if so why are they so light ?

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What will we find at the LHC?What will we find at the LHC?• There is a single fundamental Higgs scalar field. This appears to be incomplete

and unsatisfying.• Another layer of the “cosmic onion” is uncovered. Quarks and/or leptons are

composites of some new point like entity. This is historically plausible – atoms nuclei nucleons quarks.

• There is a deep connection between Lorentz generators and spin generators. Each known SM particle has a “super partner” differing by ½ unit in spin. An extended set of Higgs particles exists and a whole new “SUSY” spectroscopy exists for us to explore.

• The weak interactions become strong. Resonances appear in WW and WZ scattering as in + . A new force manifests itself, leading to a new spectroscopy.

• New massive vector bosons, Extra dimensions, Mini black holes, • Dark matter, Quark-gluon plasma state of the early universe

• “There are more things in heaven and earth than are dreamt of”

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Life at CERN

4614/09/07 Claire Timlin - Festival of Science

4714/09/07 Claire Timlin - Festival of Science

Who am I?

What do I do?

What did I do before my PhD?

Why choose a PhD?

Why Experimental Particle Physics?

Introduction

4814/09/07 Claire Timlin - Festival of Science

Atmosphere at CERN

Working on the LHC at such an interesting time

Enjoying what I do every day – Well almost!

Contributing to a field of research I

care aboutWorking in

different countries

Living near the Alps!

Working with people who are

enthusiastic about what they

do

Learning many new

skills

4914/09/07 Claire Timlin - Festival of Science

Pay: Generally

not as good as in

industry

Job Security: Can be

difficult to obtain

permanent positions in

the field

Admin: 6 weeks advance notice

required for business

trips

50Claire Timlin - Festival of Science 5014/09/07

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A Week in the Life of an Experimental A Week in the Life of an Experimental Particle Physics StudentParticle Physics Student

• Model making:– Modelling the interactions of particles

using computer programs– Figuring out why the results look like

they do– Preparing to analyse data from LHC

• Meetings:– Presenting methods and results– Lots of lively discussion!

• Researching fields of interest14/09/07 Claire Timlin - Festival of Science