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High Energy Physics at NIUHigh Energy Physics at NIU

Jerry BlazeyJerry Blazey

Northern Illinois UniversityNorthern Illinois University

Departmental ColloquiumDepartmental Colloquium

October 8, 2009October 8, 2009

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Now (15 billion yrs)Now (15 billion yrs)

Stars form (1 billion yrs)Stars form (1 billion yrs)

Atoms form (300,000 yrs)Atoms form (300,000 yrs)

Nuclei form (180 seconds)Nuclei form (180 seconds)

Protons and neutrons (10Protons and neutrons (10-10-10 s)s)

Domain of current acceleratorsDomain of current accelerators~10~10-12-12 seconds seconds

Cosmic Context Cosmic Context

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The Universe at 10The Universe at 10-12-12 s s The Standard ModelThe Standard Model

• The essence (but vague): Bits of matter stick The essence (but vague): Bits of matter stick together by exchanging stuff.together by exchanging stuff.

• The great achievement of particle physics is a The great achievement of particle physics is a nice tidy model that describes all particles nice tidy model that describes all particles and particle interactions. The model includes:and particle interactions. The model includes:– 6 quarks (the particles in the nucleus) and 6 quarks (the particles in the nucleus) and

their antiparticles.their antiparticles.– 6 leptons (of which the electron is an 6 leptons (of which the electron is an

example) and their antiparticlesexample) and their antiparticles– 4 force carrier particles 4 force carrier particles

• More precisely: “All known matter is More precisely: “All known matter is composed of composites of quarks composed of composites of quarks and leptons which interact by and leptons which interact by exchanging force carriers.” exchanging force carriers.”

4The Bits: Periodic Table of Fundamental The Bits: Periodic Table of Fundamental ParticlesParticles

-1

+2/3

-1/3

0

Mass

All point-like (down to10-18 m) spin-1/2

Fermions

Families reflectincreasing mass and

a theoreticalorganization

u, d, n, e are “normal matter”

These all interact by exchanging spin 1

bosons

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We could stop here ….

Explained by Standard Model10-37 weakerthan EM, not

explained

The Stuff: Standard Model The Stuff: Standard Model InteractionsInteractions

Mediated by Boson ExchangeMediated by Boson Exchange Unification

6There are many open and There are many open and compelling questions that can compelling questions that can

be addressed by particle be addressed by particle physics…physics…

• How do particles actually get mass?How do particles actually get mass?• Are there hidden dimensions (perhaps Are there hidden dimensions (perhaps

explaining the weakness of gravity)?explaining the weakness of gravity)?• What is the nature of dark matter and dark What is the nature of dark matter and dark

energy?energy?• What is the origin of the matter – antimatter What is the origin of the matter – antimatter

asymmetry?asymmetry?

All properties of the submicroscopic world!All properties of the submicroscopic world!

7How do we explore these ideas? First, with a particle How do we explore these ideas? First, with a particle source, for example with the Fermilab Proton-Antiproton source, for example with the Fermilab Proton-Antiproton

Collider or TevatronCollider or Tevatron

Main Injector & Recycler

Tevatron

Booster

p p

DØ

DØDØ

p source

Batavia, Illinois Chicago

1)Hydrogen Bottle2)Linear Accelerator3)Booster4)Main/Injector5)Antiproton Source6)Tevatron @ 2 TeV

You are here

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Second, with a particle detector, Second, with a particle detector, here’s a schematic examplehere’s a schematic example

Hadronic

layers

Tracking system Magnetized volume

CalorimeterInduces shower

in dense material

Innermost tracking layers

use silicon

Muon detector

Interactionpoint

Absorber material

Bend angle momentum

Electron

Experimental signature of a quark or gluon

Muon

Jet: q or g

“Missing transverse energy”

Signature of a non-interacting (or weaklyinteracting) particle like a neutrino

EM layersfine sampling

p p

9Calorimeters Tracker

Muon System

Electronics

antiprotons

20 m

• A Real Experiment: DZero• Proposed 1982• First Run: 1992-1995 1.8

TeV• Upgrade: 1996-2001• Run II: 2002-2011 2.0 TeV

• A Real Experiment: DZero• Proposed 1982• First Run: 1992-1995 1.8

TeV• Upgrade: 1996-2001• Run II: 2002-2011 2.0 TeV

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Inner Inner TrackingTracking

Electron

Quark or gluonJet

Muon

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Collider Physics is Collider Physics is International…International…

• 17 countries17 countries• 88 institutions88 institutions• 500 physicists500 physicists

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And 24/7….And 24/7….

• Proton-antiprotons collide at 7MHz Proton-antiprotons collide at 7MHz or seven million times per secondor seven million times per second

• Tiered electronics pick Tiered electronics pick successively more interesting successively more interesting eventsevents– Level 1 2 kHzLevel 1 2 kHz– Level 2 1 kHzLevel 2 1 kHz

• About 100 crates of electronics About 100 crates of electronics readout the detectors and send readout the detectors and send data to a Level 3 farm of 100+ data to a Level 3 farm of 100+ CPUs that reconstruct the dataCPUs that reconstruct the data

• Level 3Level 3: ~100 events or ~25 : ~100 events or ~25 Mbytes of data to tape per secondMbytes of data to tape per second

• Per year: 1 Trillion eventsPer year: 1 Trillion events

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Event AnalysisEvent Analysis• Events are “reconstructed” Events are “reconstructed”

offline by farms of ~100 offline by farms of ~100 CPUs.CPUs.

• Each detector samples Each detector samples position, energy, or position, energy, or momentum, 1M+ channelsmomentum, 1M+ channels

• Then computers build or Then computers build or reconstruct full event reconstruct full event characteristics based characteristics based upon these samples upon these samples

• Interesting events or Interesting events or signals are culled from signals are culled from the background usually the background usually 100’s out of 100’s out of millions.millions.

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A Sample Event: A Sample Event: ZZee++ee-- p

pZ

qq’

l

l

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Sample Distribution: Z massSample Distribution: Z mass

• Collect events and calculate mass for each event, then plot distributions

• Extract or measure properties such as mass or production rate as a function of beam brightness or luminosity.

• For example 1pb-1 of luminosity means 1 event will be produced for a process of 1pb cross section.

CDF and DØ Run II

16A Second Example: the Higgs Particle A Second Example: the Higgs Particle

(it was on the “compelling” list)(it was on the “compelling” list)

• Electroweak unification required the Electroweak unification required the assistance of the Higgs field. assistance of the Higgs field.

• This field interacts with all other This field interacts with all other particles to impart mass - think particles to impart mass - think of walking through molasses. of walking through molasses.

• The field is a microscopic The field is a microscopic property of space-time, at property of space-time, at least one real particle will result, least one real particle will result, as an excitation of the field. as an excitation of the field.

• The collider programs at The collider programs at Fermilab and CERN Fermilab and CERN are dedicated, in part, to are dedicated, in part, to the discovery and the discovery and study of this particle. study of this particle.

• For any given Higgs mass, the For any given Higgs mass, the production cross section, production cross section, decays are calculable within decays are calculable within the Standard Modelthe Standard Model

• There are dozens of ongoing There are dozens of ongoing searches in a number of searches in a number of production and decay channelsproduction and decay channels

• For example:For example:

– At low mass the Higgs could decay At low mass the Higgs could decay to a b quark/b antiquark pair and to a b quark/b antiquark pair and

– At high mass to a WW pairAt high mass to a WW pair

• Combining all searches there Combining all searches there are no events above are no events above background, so limits are set.background, so limits are set.

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Tevatron SearchesTevatron Searches

p

pW*

qq’

H

W

Or turn it around… and look for a Or turn it around… and look for a signature relevant to several signature relevant to several

signals…signals…

• Study events with 1 or Study events with 1 or 2 jets identified as 2 jets identified as coming from b-quarks coming from b-quarks using either the silicon using either the silicon vertex detector or a vertex detector or a muonmuon

• Require an energy Require an energy imbalance (“missing imbalance (“missing energy”) --> IDs energy”) --> IDs neutrinos or possible neutrinos or possible LSPLSP

• Such events maybe Such events maybe related to new physics: related to new physics: for instance ZH or for instance ZH or lepto-quark productionlepto-quark production

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DZero History/HighlightsDZero History/Highlights• 1982 initial proposals1982 initial proposals• 1983 D0 group formed1983 D0 group formed

– 12 US institutions, 71 collaborators)12 US institutions, 71 collaborators)• 1986 NIU joins D01986 NIU joins D0• 1992-1996 Run I (100 pb1992-1996 Run I (100 pb-1-1))• 1993 first top quark observed1993 first top quark observed• 1995 top quark discovered1995 top quark discovered• 1996-2001 upgrade1996-2001 upgrade• 2001 Start of Run II2001 Start of Run II• 2006 2006

– BBSS mixing and single top observed mixing and single top observed

– Precision measurements of top massPrecision measurements of top mass• 20082008

– First exclusion of Higgs MassFirst exclusion of Higgs Mass• 2011 ~12 fb2011 ~12 fb-1-1

• Through 2015 analysesThrough 2015 analyses

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NIU/NICADD DZero PersonnelNIU/NICADD DZero Personnel

• Current Current Faculty/ScientistsFaculty/Scientists– Pushpa Bhat (Fermilab)Pushpa Bhat (Fermilab)– Jerry BlazeyJerry Blazey– Dhiman Chakraborty Dhiman Chakraborty – Sasha DychkantSasha Dychkant– Mike FortnerMike Fortner– Dave HedinDave Hedin– Sergey Uzunyan Sergey Uzunyan

• Current StudentsCurrent Students– Martin Braunlich Martin Braunlich – Kenen CaymezKenen Caymez– Diego Menezes Diego Menezes – Rick SalcidoRick Salcido

• Doctoral DegreesDoctoral Degrees– Mike Eads, Search for Mike Eads, Search for

Massive Stable ParticlesMassive Stable Particles– Xiaofei Song, Search for Xiaofei Song, Search for

second generation second generation leptoquarksleptoquarks

– Andriy Zatserklyaniy, Search Andriy Zatserklyaniy, Search for third generation for third generation leptoquarksleptoquarks

– Sergey Uzunyan, Search for Sergey Uzunyan, Search for third generation leptoquarksthird generation leptoquarks

– Mike Arov, Measurements of Mike Arov, Measurements of the top cross section in the the top cross section in the tau modetau mode

• Master’sMaster’s– Linda Bagby, Layer 0 silicon Linda Bagby, Layer 0 silicon

detector and Higgs search, detector and Higgs search,

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NIU ContributionsNIU Contributions

Past (1986-2008)Past (1986-2008)• DESIGN: muon and trigger DESIGN: muon and trigger

systemssystems• CONSTRUCT: calorimeter, CONSTRUCT: calorimeter,

muon tracker, silicon muon tracker, silicon vertex, L2 trigger vertex, L2 trigger

• DEVELOP: muon, tau, L2 DEVELOP: muon, tau, L2 trigger softwaretrigger software

• COORDINATE: COORDINATE: jet, muon, tau ID groups, jet, muon, tau ID groups, QCD, B, top, New QCD, B, top, New Phenomena physics groupsPhenomena physics groups

• MANAGEMENT: trigger MANAGEMENT: trigger upgrade and collaborationupgrade and collaboration

NowNow

• Detector OperationsDetector Operations– ShiftsShifts– L2 ExpertL2 Expert– Muon softwareMuon software

• AnalysesAnalyses– Studies of top quark decayStudies of top quark decay– Searches for new Searches for new

phenomena. phenomena. • Standard model HiggsStandard model Higgs• Extensions (MSSM) Extensions (MSSM)

HH++,H,H--,h,h00,H,H00,A,A00

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DZero ProspectsDZero Prospects• Tevatron running extremely wellTevatron running extremely well

– Record integrated luminosity in the last yearRecord integrated luminosity in the last year– Just restarted after 12-week shutdownJust restarted after 12-week shutdown– Six inverse femtobarns delivered (100 X top quark Six inverse femtobarns delivered (100 X top quark

discovery)discovery)• DZero detector operating smoothlyDZero detector operating smoothly

– Upgraded in 2006 to handle current high ratesUpgraded in 2006 to handle current high rates– Still requires constant attention – Still requires constant attention –

• four physicists on shift 24/7four physicists on shift 24/7• experts on call for every subsystemexperts on call for every subsystem• Calibration and analysis continuously under Calibration and analysis continuously under

refinement. refinement. • Continue running through 2010, probably through Continue running through 2010, probably through

2011 at least2011 at least– Expect one more data doubling by end of 2011Expect one more data doubling by end of 2011– no more major shutdowns or upgrades planned – no more major shutdowns or upgrades planned –

emphasis is on physics, physics, physicsemphasis is on physics, physics, physics– Publishing ~1 paper/weekPublishing ~1 paper/week