a few ways to bring particles into your classes and to your students
DESCRIPTION
A few ways to bring particles into your classes and to your students. With thanks to Ken Cecire from QuarkNet . QuarkNet.fnal.gov has been around since some time. About this breakout session. Why : you are the best ambassadors of particle physics, as you knead the dough of the future. - PowerPoint PPT PresentationTRANSCRIPT
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A few ways to bring particles into your classes and to your students
With thanks to Ken Cecire from QuarkNet.
April 2014
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About this breakout session
• Why: you are the best ambassadors of particle physics, as you knead the dough of the future.
• What: introduce you to particle physics resources and activities that you can do with your students.
• How: go through two QuarkNet activities.– Introduction – 10’– “Quark puzzle” activity – 40’– “Plotting LHC discovery” activity – 40’– Perchance chat with Ken.
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Resources
• The International Particle Physics Outreach Group (IPPOG): http://ippog.web.cern.ch/
• QuarkNet: http://quarknet.fnal.gov/
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What we will look at today• Quark Puzzle
– students fit quark "pieces" together– use to learn about quark combination rules to form mesons and baryons with electrical
charge, color charge, matter-antimater– puzzle "workbench" and pieces (must be cut out) at
http://leptoquark.hep.nd.edu/~kcecire/mclib/files2012/QW_puzzle.pdf – instructions at
http://leptoquark.hep.nd.edu/~kcecire/mclib/files2012/Quark_Instructions.pdf • Plotting LHC Discovery
– students construct J/Psi mass plot from data, identify peak and background– students then examine a discovery plot from LHC (e.g. 4 July 2012) and pick out similar
features– description for students at
http://quarknet.us/library/upload/7/73/Discoveryplots_student.pdf– description for facilitator at
http://quarknet.us/library/upload/0/0e/Discoveryplots_tchr.pdf
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Quark puzzle
• Concepts:– Compositeness of matter at the lowest levels.– Hadrons: mesons vs. baryons.– Symmetries imply rules for composition.– Charges come in many flavours.
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Plotting LHC discovery
• Concepts:– Peaks imply correlations.– Quantities that are invariant.– Discoveries are declared at some level of
significance.
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This is not pretend science• On November 10, 1974, SLAC's Burton Richter and colleagues
found evidence for a particle they called the Ψ (the Greek letter Psi). Meanwhile on the east coast of the United States, Samuel Ting and his colleagues found comparable evidence for a particle they called the J.
• Both were the same particle and papers from both groups were published in Physical Review Letters on 2 December, 1974, as the first evidence for what is now known as the J/Ψ. Richter and Ting were jointly awarded the Nobel Prize in Physics in 1976 for the discovery, a mere two years after the work was done.
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http://cern.ch/go/S8S7
It’s the dawn of an exciting age of new discovery in particle physics!
At CERN, the LHC and its experiments are tuning up.
CMS – the Compact Muon Solenoid – has been taking data. Our job is to understand how the detector responds to data from a known Standard Model particle in the 7 TeV run from 2010.
The LHC and New Physics
The LHC is buried ~100 m below the surface near the
Swiss-French border.
The LHC and New Physics
Generic DesignCylinders wrapped around the beam pipeFrom inner to outer . . .
Tracking Electromagnetic calorimeter Hadronic calorimeter Magnet*Muon chamber
* location of magnet depends on specific detector design
Detectors
Detectors
21st April 2008 Fergus Wilson, RAL 16
The beam particles each have a total energy of 3.5 TeV:2 x 3.5 TeV = 7 TeV*
The individual particles that make up the proton only have a fraction of this energy. New particles made in the collision always have a mass smaller than that energy.
Proton Interactions
* This was the energy in the 2010 run. It has since been increased to 8 TeV.
Particle Decays
The collisions create new particles that promptly decay. Decaying particles always produce lighter particles.
Conservation laws allow us to see patterns in the decays.
Can you name some of these conservation laws?
Particle Decays
Often, quarks are scattered in collisions.
As they separate, the binding energy between them converts to sprays of new particles called jets. Muon signals can come from jets.
They are not what we are looking for.
We are studying the J/Y, a particle with no charge that decays into two muons.
What do we know about the charges of the muons? What is the charge of the J/Y?
Particle Decays
Particle Decays
An event with two oppositely charged muons might be a decay of the particle that we are interested in.
It might also be something else.
CMS Mass Plot of Z boson
Histogram Review
Well-defined peak
Outliers: lower frequency
Where is the peak?
What is the width?
Is the “mass” precise?
Histogram Review
Where is the peak?
What is the width?
Where are the outliers?
Not all histograms have same precision
Histogram Review
Twin peaks: Poor definition of one signal or Two signals
In particle physics, could be: Two separate particles or Large signal as
"background" and smaller “bump” showing actual particle under study.
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Another peak: B0s μ⟶ +μ-
April 2014Context for plot at: http://www.flickr.com/photos/uslhc/8182573711/ .
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More activities
• CMS Data Express– a "short form" of the CMS masterclass measurement that can
be accomplished in 1-2 hours and is relatively easy to use– https://quarknet.i2u2.org/document/cms-data-express
• CMS e-Lab– rather more involved; users can make mass plots and other
histograms from relatively large sets of CMS data; login as guest; I can create accounts for those who want to get investigate further for use with students.
– http://www.i2u2.org/elab/cms
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Wrap-up
• There are lots of resources out there to inspire your students.
• If you want to know more about this, drop us a line.
• Ken is available to help you with the materials/activities: [email protected]
April 2014