Particle Physics - University of Notre Damensl/Lectures/Junior_seminar/Particle_Physics.pdf · Notre Dame Physics, Junior Seminar 9/30/2009 3 Acknowledgements and Thanks… •ND

Particle Physics

Randy Ruchti

Who is involved in particle physics

• Physicists– University-based, Lab-based, Industry-based, funding- agency-based…– Experimentalists, Theorists, Accelerator Physicists

• Other Scientists and Researchers– Wide variety of fields

• Engineers– Electrical, Mechanical, Cryogenic, Computer, Safety, …

• Technical Support– Wide variety of tasks– Machinists, Tool and Die Makers, Welders, Crane Operators…

• Administrative Support– Managerial, Fiscal and Accounting, Project Coordination, Project

Reviewers,…

Notre Dame Physics, Junior Seminar 9/30/2009 2


Acknowledgements and Thanks…

• ND Experimental Particle Physics Group– L. Antonelli, B. Baumbaugh, D. Berry, L. Chan, B. Dudley, M. Hildreth,

C. Jessop, D. Karmgard, J. Kolb, T. Kolberg, K. Lannon, W. Luo, S. Lynch, J. Marchant, N. Marinelli, M. McKenna, D. Morse, J. Osta, T. Pearson, J. Slaunwhite, D. Smirnov, N. Valls, M. Vigneault, J. Warchol, M. Wayne

• ND QuarkNet Center– K. Andert, A. Beebe, T. Blacketor, L. Castle, K. Cecire, J. Chorny, K. Daily,

B. Dolezal, E. Fidler, M. Kirzeder, T. Loughran, B. Marchant, D. McDermott, A. McNeeley, P. Mooney, D. Wiand, T. Williamson, A. Zakas, J. Ziegler

• Thanks for slides from…– M. Bardeen, R. M. Barnett, M. Hildreth, E. Witten, – CMS Colleagues, ATLAS Colleagues, LHC Staff, QuarkNet Colleagues


• Take a massive explosion to create plenty of stardust and a raging heat.

• Simmer for an eternity in a background of cosmic microwaves.

• Let the ingredients congeal and leave to cool.

• Serve cold with cultures of tiny organisms 13.7 billion years later.


• To understand the basic ingredients and the ‘cooking conditions’ of the cosmos, from the beginning of time to the present day…

• Particle physicists have to try and reverse-engineer the ‘dish’ of the Universe…

• Within the complex concoction, cryptic clues hide the instructions for the cosmic recipe…


Large Hadron Collider Numbers


The Periodic Table

The story now starts with the Standard Model



Open Questions Beyond the Standard Model

• What is mass anyway?• Why are there only four forces?• Are there new types of matter?• How does Gravity fit?• How many dimensions are there in spacetime?• What is Dark Matter?• What is Dark Energy?

May find answers with the next stage of experiments at the “Energy Frontier”

10Notre Dame Physics, Junior Seminar 9/30/2009

The Energy Frontier (E=mc2)

• electron-positron colliders:

– available collision energy

u u

Ebeam

Ebeam Ebeam+

ECM ~ 2 Ebeam

e

e+ e

point-like particles


No Free Lunch: Synchrotron Radiation

• As you know, charged particles accelerated in a circle emit synchrotron radiation:

– here, P is the power radiated for relativistic (v~c) particles

– at a fixed energy and orbit, the relative rates of radiation for electrons and protons is given by the ratio of their masses to the 4th power:

• (938/0.5)4 = 1.2x1013!

it becomes impractical to build circular e+e colliders – they are too expensive to operate!

but, circular colliders are easier to run, so we use protons for the highest energy machines

2 4

2

2

3

Ke cP

r



The Energy Frontier (E=mc2)

• proton-proton or proton-antiproton colliders:

uu

d

u u

uu

d

Ebeam ½Ebeam ½Ebeam

1/6Ebeam1/6Ebeam+

ECM ~ ¹/3 Ebeam

Current: Fermilab

p p

s =1.96 TeV t = 396 ns

Run I 1992-95Run II 2001-09(?)

40 larger datasetat increased energy

Batavia, Illinois

Main Injector& Recycler

Tevatron

Booster

p

p

p source

Chicago

CDF

CDF

DØ

DØDØ

World’s Highest Energy Collider, for now






LHC Experiments




Schematic View of CMSMinus SidePlus Side


The CMS Collaboration

2310 Scientific Authors

38 Countries

175 Institutions

CERN

France

Italy

UK

Switzerland

USA

Austria

Finland

Greece

Hungary

Belgium

Poland

Portugal

Spain

Pakistan

Georgia

Armenia

Ukraine

Uzbekistan

CyprusCroatia

China, PR

Turkey

Belarus

Estonia

India

Germany

Korea

Russia

Bulgaria

China (Taiwan)

Iran

Serbia

New-Zealand

Brazil

Ireland

1084

503

723

2310

Member States

Non-Member States

Total

USA

# Scientific

Authors

59

49

175

Member States

Total

USA

67Non-Member States

Number of

Laboratories

Associated Institutes

Number of Scientists

Number of Laboratories

62

9

Oct. 3rd 2007/gm

Mexico ColombiaLithuania

CMS Physics Week, Bologna, Italy, September 2009



CMS Site Under Construction



Experiment Cavern2003

2004




Elements of the Detector

HCAL

Magnet

Tracker

Muon chambers

ECAL


Final Closure



No RF, debunching in ~ 25*10 turns, i.e. roughly 25 mS

33Courtesy E. Ciapala


First attempt at capture, at exactly the wrong injection phase…



Capture with corrected injection phasing



Capture with optimum injection phasing, correct reference








HCAL

Magnet

Tracker

Muon chambers

ECAL


While waiting for protons…

Eta towerphi tower

Top wedges

Bottom wedges

HB

YB0


Cosmic Rays in the Tracker


Elements of the CMS research plan

• Certify the detectors and validate data

– Revisit the Standard Model

• Searches

– New Phenomena - Forces

– Higgs Bosons - Mass

– Supersymmetry – Dark Matter

– Extra Dimensions of Spacetime

– And…the unexpected!


A hypothesized new particle Z'


A Higgs Boson


To understand the Higgs mechanism, imagine that a room full of physicists chattering quietly is like space filled with the Higgs field ...

Higgs and Mass


... a well-known scientist walks in, creating a disturbance as he moves across the room and attracting a cluster of admirers with each step ...

... this increases his resistance to movement, in other words, he acquires mass, just like a particle moving through the Higgs field...


... if a rumor crosses the room, ...

... it creates the same kind of clustering, but this time among the scientists themselves. In this analogy, these clusters are the Higgs particles.





Supersymmetry

For fundamental particles, supersymmetry says:

Every matter particle(fermion) should be associated with a massive “shadow” force carrier particle (boson).

Every force carrier particle should have a massive “shadow” matter particle.

This has possible implications for Dark Matter

If Supersymmetry, then…




Extra Dimensions of Space?

Think about an acrobat and a bug on a tight rope.

The acrobat can move forward and backward along the rope.

But the bug can also move sideways around the rope.

If the flea keeps walking to one side, it goes around the rope and winds up where it started.


Extra Dimensions of Space

in Science? More than String Theory?

Which is weaker: Gravity or Electromagnetism?

electromagnetismgravity

Why is gravity so weak?


Escaping into extra dimension


Interesting Physics Processes

that will be produced at LHC in

early accelerator operation

Process Events/year

W -> e nu 400 million

Z -> e e 40 million

t tbar 16 million

b bar 1 trillion

gluino-gluino ( m = 1TeV ) 20,000

Higgs (m = 120 GeV) 800,000

Higgs (m = 800 GeV) 10,000

QCD jets (pT > 200 GeV/c) 1 billion


QuarkNet52 Centers in 25 states and Puerto Rico

500 HS Teachers150 Particle Physicist mentors100 HS Students annually

A professional development program for HS Teachers with immersive research experience for HS teachers and students.

Now in its 10th year. Supported by NSF and DOE

http://quarknet.fnal.gov/

http://quarknet.fnal.gov/

Particle Physics - University of Notre Damensl/Lectures/Junior_seminar/Particle_Physics.pdf · Notre Dame Physics, Junior Seminar 9/30/2009 3 Acknowledgements and Thanks… •ND

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