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The Large Hadron ColliderThe Large Hadron ColliderIs Turning On (Again)Is Turning On (Again)

In NovemberIn November

Michael ShupeMichael ShupeDepartment of Physics Department of Physics

University of ArizonaUniversity of Arizona

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French/Swiss Countryside outside Geneva, Switzerland.

Large Hadron ColliderLarge Hadron Collider

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Large Hadron ColliderLarge Hadron Collider

At four points around At four points around the ring the two beams the ring the two beams are brought together for are brought together for head-on collisions.head-on collisions.

The beams are actually The beams are actually composed of many composed of many bunches of protons, bunches of protons, with bunch crossings with bunch crossings (collisions) every 25 (collisions) every 25 nanoseconds.nanoseconds.

At nominal energy, it At nominal energy, it takes 90 microseconds takes 90 microseconds for a proton to make for a proton to make one revolution.one revolution. 7 GeV 7 GeV

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LHC experiments, and a few of the physicists…LHC experiments, and a few of the physicists…

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The ATLAS DetectorThe ATLAS Detector7000 tons of detector sits 100m underground150 million sensors incorporated into ATLAS

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The ATLAS DetectorThe ATLAS DetectorOne of four experiments at the LHC: 46m in length

and 25m in diameter. 100 m underground.

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ATLAS By The NumbersATLAS By The Numbers SizeSize

½ size of Notre Dame Cathedral½ size of Notre Dame Cathedral Weighs as much as 100 747 airplanesWeighs as much as 100 747 airplanes

DataData 3200 terabytes expected3200 terabytes expected Equivalent to 7km of CDs stacked verticallyEquivalent to 7km of CDs stacked vertically

Energy and TemperatureEnergy and Temperature 7 times the energy of any existing accelerator7 times the energy of any existing accelerator 100,000 times hotter than the sun100,000 times hotter than the sun

CollaborationCollaboration 2500 physicists2500 physicists 37 countries37 countries 169 universities and laboratories169 universities and laboratories

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To study the To study the fundamental building fundamental building blocks of nature, and blocks of nature, and

the interactions among the interactions among them.them.

Electromagnetic ForceElectromagnetic Force

Strong (Nuclear) ForceStrong (Nuclear) Force

Weak Force (Changes Weak Force (Changes particle types)particle types)

Gravity (Gravitons?)Gravity (Gravitons?)

What’s the LHC for?What’s the LHC for?

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LHC and the Big BangLHC and the Big Bang

At the LHC we will recreate temperatures similar to those found aboutone nanosecond after the Big Bang.

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What Can Be Found at the What Can Be Found at the LHC?LHC?

Source of mass: find the Higgs particle?Source of mass: find the Higgs particle? Confirm new theories: Supersymmetry?Confirm new theories: Supersymmetry? Astrophysical phenomena: Dark Matter particles?Astrophysical phenomena: Dark Matter particles? More BTSM: Compositeness?, Extra Large Dimensions?More BTSM: Compositeness?, Extra Large Dimensions? Complete surprises? (See the history of this field.)Complete surprises? (See the history of this field.)

Dennis Overbye

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Mass puzzle, and the Higgs Mass puzzle, and the Higgs Particle.Particle.

The standard model of The standard model of particle physics works particle physics works wonderfully well.wonderfully well. Unification of the Unification of the

Electromagnetic and Electromagnetic and Weak Forces.Weak Forces.

Form of the Strong Force.Form of the Strong Force. But it does not explain But it does not explain

why particles have why particles have massesmasses nor why some nor why some particles are very light particles are very light while others are very while others are very massive.massive.Providing mass to all massive particles is role of the Providing mass to all massive particles is role of the predicted Higgs particle. We are searching for the predicted Higgs particle. We are searching for the

Higgs at the LHC.Higgs at the LHC.

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Finding a HiggsFinding a Higgs A Higgs, if it is produced at the LHC, A Higgs, if it is produced at the LHC,

will decay immediately into other will decay immediately into other lighter particles.lighter particles. Such particles can be reconstructed in a Such particles can be reconstructed in a

detector (ATLAS, CMS).detector (ATLAS, CMS). By searching for these “daughter” By searching for these “daughter”

particles, one can reconstruct the Higgs.particles, one can reconstruct the Higgs. Many other decays can mimic a Higgs, Many other decays can mimic a Higgs,

producing background.producing background.

A few hundred Higgs events seen after a few years of running

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Dark MatterDark Matter

From Newtonian mechanics we expect the rotational velocity of From Newtonian mechanics we expect the rotational velocity of galaxies to drop off with radius.galaxies to drop off with radius. Pluto’s orbit is about 250 times longer than Earth’s even though it’s Pluto’s orbit is about 250 times longer than Earth’s even though it’s

only 40 times farther from the Sun.only 40 times farther from the Sun. Data show that velocities remain nearly constant.Data show that velocities remain nearly constant.

Galaxies should fly apart.Galaxies should fly apart. Indication that all mass in galaxies is not contained in stars.Indication that all mass in galaxies is not contained in stars.

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Dark Matter CandidatesDark Matter Candidates Weakly Interacting Massive Particles Weakly Interacting Massive Particles

WIMPsWIMPs As yet undiscovered particle/particlesAs yet undiscovered particle/particles Only interacts via the weak force and Only interacts via the weak force and

gravity.gravity. A leading WIMP candidate is the A leading WIMP candidate is the

neutralino.neutralino. If this particle exists, it is likely to be If this particle exists, it is likely to be

found at the LHC.found at the LHC.

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This is one of the new-physics directions This is one of the new-physics directions being pursued at Arizona:being pursued at Arizona:

Leading an effort to search for a charged Leading an effort to search for a charged Higgs particle decaying into a chargino Higgs particle decaying into a chargino and neutralino.and neutralino. Definitive evidence for physics beyond Definitive evidence for physics beyond

the Standard Model.the Standard Model. The neutralino may be the solution to The neutralino may be the solution to

the dark matter problem.the dark matter problem. One of many scenarios for the decay of One of many scenarios for the decay of

the Higgs particle.the Higgs particle.

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The University of Arizona The University of Arizona TeamTeam

Faculty

Research Associates & Staff

Students

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The ATLAS DetectorThe ATLAS Detector Arizona’s contributions to ATLAS.Arizona’s contributions to ATLAS.

Forward CalorimeterForward Calorimeter Forward Muon ChambersForward Muon Chambers Radiation StudiesRadiation Studies Development of Data AnalysisDevelopment of Data Analysis

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LAr CalorimetersLAr Calorimeters

Arizona

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Close-up photo of the front of one of the forward calorimeter modules during construction.

One of the prototypes for this detector element is located in the hallway.

Cutaway drawing of one FCal module. The LHC accelerator vacuum beam pipe passes through the hole in the middle of the module.

Forward Calorimeter

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Forward Calorimeter Construction in the Basement of Forward Calorimeter Construction in the Basement of Physics: Even Experimentalists Dress Up OccasionallyPhysics: Even Experimentalists Dress Up Occasionally

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Forward Calorimeter InstallationForward Calorimeter Installation

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Muon DetectorMuon DetectorMuons are the only charged particles which can pass through the calorimeters. The muon system detects such particles and can determine their charge and momentum.

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CSC (Cathode Strip CSC (Cathode Strip Chambers)Chambers)

CSCs

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CSC ChambersCSC Chambers

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One of My Physics Interests: Quark One of My Physics Interests: Quark CompositenessCompositeness

Are there smaller Are there smaller things inside quarks?things inside quarks?

Recall Rutherford Recall Rutherford Scattering: excess Scattering: excess events at large events at large angles.angles.

LHC analogy is quark LHC analogy is quark collisions with large collisions with large momentum transfer. momentum transfer. Small scattering Small scattering centers inside quarks centers inside quarks would modify the pwould modify the pTT distribution. (“Jets” distribution. (“Jets” simulation for ATLAS simulation for ATLAS shown at right.)shown at right.)

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One of My Service Contributions: ATLAS One of My Service Contributions: ATLAS Backgrounds Simulation, and Shielding Backgrounds Simulation, and Shielding

DesignDesign

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Installation of bridge piece for ATLAS forward shield.Installation of bridge piece for ATLAS forward shield.

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What next?What next? Next beam in LHC: NovemberNext beam in LHC: November First collisions: December.First collisions: December. First low energy data: Spring 2010First low energy data: Spring 2010 Increase in rate & energy: 2010 – Increase in rate & energy: 2010 –

20112011 First Discoveries in 2011…First Discoveries in 2011…

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SummarySummary The LHC turn on has just begun.The LHC turn on has just begun. World’s largest scientific experiment to World’s largest scientific experiment to

date.date. Expect to find answers to many Expect to find answers to many

fundamental questions.fundamental questions. Mass, Dark Matter, Supersymmetry, and More!Mass, Dark Matter, Supersymmetry, and More!

The University of Arizona has played a The University of Arizona has played a significant role in developing and building significant role in developing and building this device.this device.

Exciting times ahead…Exciting times ahead…

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CSC Muon ChambersCSC Muon Chambers

Resolution is 70 μm

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CSC Calibration SystemCSC Calibration System

Improves resolutionImproves resolution Allows detector to Allows detector to

operated in a high rate operated in a high rate environment.environment.

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EM CalorimeterEM Calorimeter

Barrel in cryostat

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