Notre%20Dame%20High%20Energy%20Physics%20Hadron%20Collider%20Group

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Notre DameHigh Energy Physics Hadron Collider
Group

• The Group
• 8 graduate students (details later)
• 7 research faculty/postdocs
• Leo Chan, Dongwook Jang, Dan Karmgard, Prolay
  Mal, Nancy Maranelli, Dmitri Smirnov, Jadzia
  Warchol
• 3 technicians plus 1 engineer
• Jeff Marchant, Mike McKenna, Mark Vigneault,
  Barry Baumbaugh
• 5 teaching and research faculty
• Anna Goussiou, Mike Hildreth, Colin Jessop, Randy
  Ruchti, Mitch Wayne
  

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Experimental Projects

• DØ at the Fermilab Tevatron
• proton-antiproton collisions at 2.0 TeV
• 7 Ph.D. students on Run I
• detector construction, commissioning for upgrade
• widespread current effort in Run II
• many physics analyses, software development,
  detector operation
• CMS at the CERN LHC
• proton-proton collisions at 14.0 TeV
• detector development, construction, testing,
  commissioning
• Quarknet program for H.S. students, teachers
• International Linear Collider
• RD on Muon System, Beam Instrumentation

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Past DØ Ph. D. Students
? V. Balamurali - Medical school
? Linda Coney - Postdoc, Columbia Univ., FNAL
? Jim Jaques - ATT laboratories
? Bob Kehoe - Faculty, SMU
? Evgeny Popkov - Postdoc, Boston Univ.
? Hai Zheng - Postdoc, Caltech
? Mike Kelly - Private Sector
Ryan Hooper - Postdoc, Brown Univ., Priv. Sect.
Lucas Xuan - Postdoc, Univ. of Hawaii
Julie Torborg - Faculty, St. Cloud
Eugene Galyaev - Postdoc, Univ. of Texas

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Current Students
DØ
? Yury Pogorelov - Russia
? Peter Svoisky - Russia
? David Lam - Canada
? Jyotsna Osta - India
Sarah Schlobohm - U.S.
Tyler Dorland - U.S.

Ted Kolberg - U.S.
Justin Griffiths - U.S.
CMS
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• Now (15 billion years)

Stars form (1 billion years)
Atoms form (300,000 years)
Nuclei form (180 seconds)
Protons and neutrons form (10-10 seconds)
Quarks differentiate (10-34 seconds?)
??? (Before that)
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What is the Universe Made of?

• A very old question, answered many ways during
  the eons
• The only way to answer this question is by
  directly confronting Nature by experiments that
  can lead to definite conclusions
• Experiments have told us
• complexity often arises from simple building
  blocks
• Periodic Table of the Elements, Nuclear Structure
• fundamental constituents are small particles
• diverse phenomena can be manifestations of the
  same underlying physics
• the moons orbit, a falling apple
• intuition may not necessarily be trustworthy
• our world is really Quantum Mechanical, even
  though we dont see this in everyday life

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Fundamental Forces of Nature
Relative Strengths 10-40 10-2 10-6 1

• Gravity
• Electromagnetism
• Weak Nuclear Force
• Strong Nuclear Force

The ElectroWeak and Strong forces combine to form
the Standard Model of Particle Physics
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Particles Mediating Forces

• virtual particles fly back and forth
• Nuclear decay the weak force

e
e
g
Uncertainty Principle DE Dt h (10-34 J s)
e
e
u
n
p
e
d
W
n
E mc2 Energy becomes matter!
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Open Questions in the Standard Model

• Without getting into the Structure of the
  Universe, there are some obvious questions here
• Why are there three families?
• Why are there pairs of particles in each family?
• Why are the masses so different?
• How is the Strong Force related to the
  Electroweak Force?
• Why are the forces such different strengths?
• What about Gravity?
• This is some of what we are trying to answer...

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On to Big Questions

• Particle Physics experiments may also answer
• What IS mass?
• Why is there matter at all?
• What is Dark Matter?
• What is the space-time structure of the Universe?
• ? Growing synergy between particle and
  astrophysics
• both fields working together on these questions

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Question 1 What is Mass?

• Pretty basic question
• The Standard Model gives us no clue where the
  fermion masses come from, and what the origin of
  their hierarchical structure is
• We DO have an idea of where the boson masses come
  from, though...
• It turns out that this is related to another
  question
• Why do the forces have different strengths?

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Electroweak Symmetry Breaking
Unified Electroweak Theory
? Our World!
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The Higgs Mechanism

• In the Standard Model, Electroweak symmetry is
  broken by the addition of a scalar field which
  permeates all of space
• the Higgs Field
• the W and Z bosons mix with this field and
  acquire mass
• essentially, the Higgs resets the vacuum of the
  Universe
• All parameters (couplings, decay rates, etc)
  except its mass, are fixed in the Standard Model
• One definite prediction of this theory
• there is a scalar particle called the Higgs Boson
  which is an excitation of the fundamental field
• We can look for it!
• J. Womerlsey Pluck the violin string of the
  Universe

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The Higgs boson/field

• Think of identical boats on a lake

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The Higgs boson/field
Think of identical boats on a
lake Underneath Shape of keel
determines Resistance(mass) in Lake(Higgs field)
Higgs boson
Wind(Force) ma
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Question 2 What is Dark Matter?

• responsible for the clumping of galaxies
• determines large scale structure of the Universe
• can we see it experimentally?
• is it new physics?

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Why Dark Matter?

• Gravitational wells of galaxies are bigger than
  the visible matter
• galactic rotation curves, etc.
• Mass of ordinary matter insufficient to form
  large-scale structure
• proton mass binding energy
• BBNS and D/He abundance set scale for matter
• Example of LCDM Simulation vs. Real Life

A. Kravstov, NCSA, UofC
CDM preferred? heavy, slow
G. Bryan, M. Norman
Sloan Digital Sky Survey
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WMAP Results

• Most comprehensive measurement of CMB to date
• Precise measurement of cosmological quantities
• ?M 0.27 0.04
• ?B 0.044 0.004
• the other 70 of the energy density is dark
  energy

LCDM Fit
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What is this stuff?

• Slow, heavy, weakly-interacting, neutral
• relics from the early universe
• stable
• WIMPs?
• Can we see them experimentally?
• look for interactions as we swim through them
• try to produce them at particle accelerators
• measure their properties, masses, etc.
• But, what signatures should we look for?
• guidance from theorists
• Could be Supersymmetry!

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Supersymmetry
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Searching for SUSY at the Tevatron

• squarks and gluinos have the highest production
  probability
• If supersymmetry-ness (R-parity) is conserved,
  decay cascades always end up with stable lightest
  neutralino (think photon)
• LSP escapes from the detector ? missing ET

make Dark Matter at the Tevatron
LSP
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Question 3 What is the Structure of the
Spacetime?

• how many dimensions are there?
• how can we probe them experimentally?
• is geometry the answer to many of our questions?

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Large Extra Dimensions

• If this sounds a little far-fetched...

• Explosion of interest in these ideas
• Many different models
• - Large Extra Dimensions (ADD)
• - TeV-Scale Extra Dimensions
• - Warped Extra Dimensions (RS)
• All sorts of variations to try and solve all
  possible problems

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Signatures at Colliders

• Could be immediate and quite spectacular
• Or more indirect
• Virutual Graviton emission can enhance production
  of ?? or gg pairs with high mass and large pT

tiny black holes could form, then evaporate
instantaneously via Hawking Radiation
Focus on these first, since they are the most
likely to appear at the Tevatron
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The DØ Experiment atthe Fermilab Tevatron
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Fermilab
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pp Collisions at the Tevatron

• Counter-rotating bunches of protons and
  anti-protons collide head-on in the two
  interaction regions
• use protons for maximum energy reach
• Each particle has an energy of 9.8x1011 Volts
  (980 GeV)

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DØ in the Collision Hall
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The guts of DØ
p
p
Note Side view
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Tracker Detail

• Central Fiber Tracker
• 77k fibers in eight barrels, 800 mm diameter
  fibers
• 3 stereo layers in each barrel
• VLPC readout, 7 photo-electrons/track at h 0

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The Tracker in Action
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(some of) The people that built DØ
670 physicists 80 institutions 19
countries 120 grad students gt50 non-US
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Run II Data on Tape!

• The experiment is operating well
• Already 20x Run I!
• Full 1 fb-1 used for analysis for Winter 2006
  Conferences

Run 1 total
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Luminosity Projections
Spring 2009
Data on Tape (fb-1)
3-5x data!
Now
Time
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The CMS Experiment at the LHC

• CERN Geneva, Switzerland
• LHC Large Hadron Collider
• Proton Proton collider
• Beam energy 7 TeV 7 TeV
• Several large experiments CMS, ATLAS
• First collisions 2007-2008!

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Physics Goals

• The same Big Questions but with 7x the reach

SUSY
Dark Matter
TeVatron
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CMS Assembly HallMuon End Disk and Endcap
Calorimeter
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CMS Assembly HallHalf of the Hadron Calorimeter
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Being Installed!
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ODU for CMS HCAL
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LHC Physics Center at Fermilab

• Center for US involvement in CMS
• local center of software/analysis expertise
• preparing to be very active in commissioning CMS
• Close!
• Easy way to get involved part time
• developing tutorials, example analysis packages,
  etc.
• nucleus of consultants for newcomers
• Senior ND personnel involved

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CMS Summary

• Beam testing of elements 2003-2006
• Slice testing of detector elements 2006
• Magnet test completed 2006
• Installation underground 2006-2007
• Run starts 2007!
• First data analyses now-2007-2010

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International Linear Collider

• Future ee- Linear Collider
• Center of Mass energy from 0.5 1.5 TeV
• Precision Measurements to complement LHC
• Same questions, different approach

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ILC RD
test beam at SLAC
Beam Energy Spectrometer
Prototype Muon Detector
test beam at FNAL
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Conclusions

• Not an easy game, but the payoff could be HUGE
• Origin of mass?
• Understanding Energy Scales for the Fundamental
  Forces?
• New forms of matter (Supersymmetry)?
• Structure of Spacetime
• DØ will be collecting up to 5x the current
  dataset over the next 3 years or so, CMS coming
  very fast
• lots of scope for new phenomena to appear
• Fascinating time to be a particle physicist
• If we dont find new things at the Tevatron, the
  LHC will
• huge jump in energy and data quantity
• Within the coming years, we will have answers!
• (and more questions, of course)

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