Tiny URL for this page:  http://tinyurl.com/atlasde0.

Introduction 

ATLAS Data Express is a short particle physics masterclass investigation that can be used as part of a workshop or as a short class project. Participants examine static displays of a limited number of events. The main goal is to separate Z candidate events other events by visual inspection and then create mass plot for the Z boson.

The Z boson is important in LHC discovery science and as a marker for calibration of LHC detectors: it is a well-known particle, so the location and width of the mass plot give physicists a good idea of how the detector is performing. The Z candidate events we will study are "dimuon"  events; the Z can decay into a muon-antimuon pair. Z candidates are identified by 2 long muon tracks; each will appear as a combination of a short blue track in the inner detector (inner black ring) and a longer orange track in the outer muon chambers (blue rings). Participants will search for Z candidates in the data.

Instructions

Individual or pair:

• Participate in analysis prep seminar (slides) (ATLAS animation)
• Open the event display file
• Go to set of events assigned
• Categorize and record each event as
  • Z → μ⁺μ^- candidate (2 distinct muon tracks),
  • background (anything else).
• For each Z candidate, note and record
  • the mass, rounded to nearest odd number (found at upper right of event) 
  • whether it is an electron or a muon event.
• When finished, count how many instances of each odd number you have recorded.

Group:

Use your own resources to

• Combine numbers of "odd masses" in all groups.
• Create a histogram for whole group to observe.
• Analyze other aspects of the data (optional).

Help: Use the Google spreadsheet.

Discussion

The histogram created by the group is a mass plot. Since the mass of any one type of particle is uncertain by nature and due to experimental uncertainty, it will have a distribution the peak of which is the experimental determination of the mass. Creation of mass plots and other histograms are the central measurements made in the CMS e-Lab but with many more events than used in this exercise.

Resources

• Histograms
• Units in particle physics
• Events
• ATLAS Masterclass Analysis Prep

Agenda elemnts:

1. ATLAS or CMS virtual visit with an engineer
2. Making it 'round the bend
3. Design problem - getting to high field
4. Calorimeter actvity
5. Design problem - stopping high energy particles
6. Testing activity (with ODUs? fiber? CRMD blessing and perf?)
7. Tie together; discussion

Tiny URL for this page: http://tinyurl.com/qnilcmmc14.

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This is the original explanation, more sutiable for LHC fellows, of the Event of the Month that Marla wrote:

English version

Version français

What are they?

                             Sample Event 1                                                                    Sample Event 2

                       It's a Z boson candidate!                                                     It's a W+ boson candidate!

                               Sample Event 3                                                                    Sample Event 4      

                    It's a Higgs boson candidate!                                                     It's a W- boson candidate!

Version français

Learn about the events!

Use the Guide Sheet	View the Screencast
View the slides.	Play with the CMS Animation

Try out some particle IDs!

Sample Event 1 Is it a W+, W-, Z, or Higgs?	Sample Event 2 Is it a W+, W-, Z, or Higgs?
Sample Event 3 Is it a W+, W-, Z, or Higgs?	Sample Event 4 Is it a W+, W-, Z, or Higgs?

See the results!

More stuff!

• CMS Masterclass

• Notre Dame QuarkNet

• Notre Dame Physics

• All of today's bosons

• Contact Us

English version

Evaluation data has shown that students who have been prepared for masterclasses report getting significantly more our of them and like them better.

Prior Knowledge for Masterclasses / Classroom Prep Objectives

Meeting these objectives will assure that students are well prepared for the masterclass.

• Describe the claim and indirect evidence in Rutherford's or another key experiment.
• Identify the peak in a histogram and explain what it means.
• Describe how quarks combine to form mesons and baryons.
• Apply conservation rules to measurements to provide evidence for unobserved particles.

Suggested Activities

Particle physics research requires the use of indirect evidence to support claims.
Rolling with Rutherford
Students will be able to:

• Describe the claim and indirect evidence in Rutherford’s experiment.
• Identify the peak in a histogram and explain what it means.

The Standard Model is the current theoretical framework for our understanding of matter.
Quark Workbench (instructions)
Students will be able to:

• Describe how quarks combine to form mesons and baryons.

The behavior of particles is governed by conservation laws and mass-energy conversion.

Choose one or both:

• Top Quark Mass Reconstruction
• Mass Calc: Z

Students will be able to:

• Apply conservation rules to measurements to provide evidence for unobserved particles.

Additional Resources

• CMS videos
• ATLAS videos
• The Particle Adventure
• Bubble Chamber Activity
• Hands-on CERN