finding the higgs boson pdgusers.lbl/~pequenao/camelia/index2.html
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Finding the Higgs Boson http://pdgusers.lbl.gov/~pequenao/camelia/index2.html. LHC Practical Session - Intro. Who am I. Who are we? What are we looking at/for? Accelerating Particles Detectors The Higgs The Benefits. Who am I?. PhD Student at University of Liverpool - PowerPoint PPT PresentationTRANSCRIPT
22/04/23
Finding the Higgs Boson
http://pdgusers.lbl.gov/~pequenao/camelia/index2.html
22/04/23
o Who am I. Who are we?
o What are we looking at/for?
o Accelerating Particles
o Detectors
oThe Higgs
o The Benefits
LHC Practical Session - Intro
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PhD Student at University of Liverpool Get paid a tax free allowance by the governmentAfter 3-4 years I write a thesis and become a Dr
Lived in Geneva for 18 months
* I hope, fingers crossed
Who am I?
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CERN: Conseil Européen pour la Recherche Nucléaire
An International Organisation (like UN, WHO, etc) for physics research, non Europeans are heavily involved as observers. More than 10000 users
The Large Hadron Collider (LHC) is an apparatus to accelerate protons to be collided at four experiments
The 2010 Budget was 1.1 billion CHF (730 million £), spread amongst member states. One cup of coffee per European citizen per year
What is CERN and the LHC?
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What is CERN and the LHC?
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The ‘Standard Model’ of Physics
These are our everyday particles that we are made of.
We have extra Generations, similar to this but heavier
These quarks make protons and neutrons!
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The ‘Standard Model’ of Physics
These heavier generations do not occur in our usual lives, we need to use high energy colliders to make them.
BUT we also need force carrying particles
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The ‘Standard Model’ of Physics
We are missing gravity here, we can’t fit it in this picture as Einstein described it
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The ‘Standard Model’ of Physics
We think Gravity should have a force carrying particle too, the Gravition but we can’t see it at our current energies!
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Now a rumour circulates the celebrity is in the room, everyone asks each other about it. Soon a huddle of people forms, more join as they think the celebrity must be there, it again becomes hard to move. This is like the action of the Higgs field, giving particles mass, making it harder to move them.
As a Higgs analogy imagine a party. A celebrity enters & a huddle forms around him/her, making it hard to move, this is like the Higgs Particle
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Methods of Particle Physics
3) Identify created particles inDetectors (search for new clues)
1) Concentrate energy on particles (accelerator)
2) Collide particles (recreate conditions after Big Bang)
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p
In the LHC particles are accelerated to 7 000 000 000 000 volts (7 TeV)
p
•Accelerate charged particles using electric fields•Bend and focus the charged particles using magnetic fields
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CERN's mission:to build particle acceleratorsThe Large Hadron Collider (LHC) is the most powerful
instrument ever built to investigate particle properties.
• Four gigantic underground caverns to host the huge detectors
• The highest energy of any accelerator in the world
• The most intense beams of colliding particles
• It operates at a temperature colder than outer space
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Computing
o Huge amounts of data
o Need lots of computing hours to
process all of this
o CERN created the GRID,
linking computing clusters
around the world for parellel
processing
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CERN: where the Web was born!
Sir Tim Berners-Lee
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How to x-ray a lorry !Using wire chambers, invented at CERN
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PET scanners, MRIs
Medical applications
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Medical applications
AD-4 experiment trying to improve on proton therapy for cancer
with anti-proton therapy
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Summary: CERN is the largest laboratory for particle physics research in the world
Basic research: study how the most basic matter we know (or theorise) behaves to describe how mass and forces work
Summary
Now for the Practical Part
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Interactively finding the Higgs
http://pdgusers.lbl.gov/~pequenao/camelia/index2.html
Today, using real events from the LHC, you are going to be looking for the Higgs
,
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Finding the Higgs
• Unfortunately the Higgs decays in less than a millionth of a second
• Have to detect the mundane things it decays into• However, we get these signatures million times more
often from non Higgs events• Have to distinguish the Higgs from background,
looking for a needle in a massive haystack!
We expect only 1 Higgs in1,000,000,000,000 events
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Finding the Higgs
Today you are going to try and look for Higgs decaying into four muons, via two Z particles
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Finding the Higgs
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Finding the Higgs Boson
TimeCharge Energy Position
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Finding the Higgs
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ATLAS A General Purpose Detector
• Full coverage, meaning particles detected in virtually every direction,
• Magnets, electronics and structural support inside detector
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Finding the Higgs Boson
TimeCharge Energy Position
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Interactively finding the Higgs
http://pdgusers.lbl.gov/~pequenao/camelia/index2.html
Pt = Momentum Transverse to the incoming beamGeV = Giga electronVolts, our units of Energy (We use
Energy and Momentum interchangeably)
Higgs Mass = 125GeV, Z mass = 91 GeV
Invariant Mass = If a particle decays into two others, we can sum up their energy/momentum in the viewpoint of
the original particle to tell us it’s mass
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LHCb: Precision over small angles
• Only detects particles going forward in 14 degree angle• High precision, detector only 5mm from collision point