High Energy Physics (HEP) Overview

Most slides taken from previous Quarknet presentations, particularly Jeremy’s from 2020!

What are we looking at?

What are we measuring and how do we understand what we see?

What are the learning goals?

The Standard Model

There’s more! Resources:

• Particle Adventure (good resource for students)
• Hyperphysics particle physics topics (medium difficulty between these two resources)
• Particle Data Group PDG (detailed resource, includes pamphlet you can order or use interactive online version)

*thanks Jeremy for researching these!

The LHC and New Physics

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🡨 ATLAS detector

Generic Particle Detector

Cylinders wrapped around the beam pipe

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From inner to outer . . .

Tracking

Electromagnetic calorimeter

Hadronic calorimeter

Magnet*

Muon chamber

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* location of magnet depends on specific detector design

Detector Tracks

All detectors have 4 basic layers

Detector Tracks

Energy & Particle Mass

If each beam proton has energy 4 TeV....

• The total collision energy is 2 x 4 TeV = 8 TeV
• Each particle inside a proton shares only a portion
• A newly created particle’s mass must be smaller than the total energy

Particle Decays

The collisions create new particles that promptly decay.

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Decaying particles always produce lighter particles.

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Conservation laws allow us to see patterns in the decays.

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Ex) neutral, large blue decays into net neutral, smaller reds

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film

Higgs Particle Production

The Higgs boson decays into daughter particles, sometimes including muons.

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Other particles also produce muons, such as the Z boson.

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Still more resources!

CERN detector overview, good for students

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Detailed presentation on detector physics, includes historical overview

https://www.desy.de/~garutti/LECTURES/ParticleDetectorSS12/L1_Introduction_HEPdetectors.pdf

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A Word About Units

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Qty Formula SI Unit HEP Unit

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Energy K~mv² Joule GeV

Mom. p=mv J/speed GeV/c

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Mass m J/speed² GeV/c²

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Make c = 1 and E = p = m, everything in GeV