particle physics - university of notre damensl/lectures/junior_seminar/particle_physics.pdf ·...
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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,…
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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
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• 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.
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• 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…
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”
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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
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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
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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
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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
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Elements of the Detector
HCAL
Magnet
Tracker
Muon chambers
ECAL
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No RF, debunching in ~ 25*10 turns, i.e. roughly 25 mS
33Courtesy E. Ciapala
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First attempt at capture, at exactly the wrong injection phase…
34Courtesy E. Ciapala
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Capture with corrected injection phasing
35Courtesy E. Ciapala
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Capture with optimum injection phasing, correct reference
36Courtesy E. Ciapala
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While waiting for protons…
Eta towerphi tower
Top wedges
Bottom wedges
HB
YB0
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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!
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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
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... 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...
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... 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.
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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
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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.
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Extra Dimensions of Space
in Science? More than String Theory?
Which is weaker: Gravity or Electromagnetism?
electromagnetismgravity
Why is gravity so weak?
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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
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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/