What is Fermilab? - Run II Newscasts - Analyze the Data - Particle Physics Bibliography

Teacher Page - Classroom Notes - Alignment with Standards - Student Data Analysis Homepage

Classroom Notes - Site Map
These investigations are provided online as a student-led, teacher-guided project. After a few introductory pages including links to reference materials, the project breaks into two natural parts: identifying B mesons and identifying W bosons. (Each has a special project either calculating the B lifetime or calculating the W mass. The W mass calculation has a second component, finding a correction factor by calculating the Z mass.) Then, all come together in a culminating activity to find Higgs mass.

Working in small teams, students can do all four investigations, or you can create teams of say six students and they can divide the first projects among themselves. Then, they can pool their knowledge to complete the Higgs project. If you want your students to do the special projects, you may want to have students calculate the W mass without finding the correction factor (~1.065) from the Z mass themselves. We provide check point for students to ask you how to proceed.

As you study the calculations and graphs, you will see that there is not one right answer to these investigations. Students have to use their judgment to decide what bin size to use to plot the histogram and what number to read from the plot of the histrogram. Have each group report their results and discuss why they are different, how the class might determine the "best" number from their read of the data and what that tells them about how scientists work.

To help students become familiar with event pictures, we have included a short activity where students classify event pictures according to characteristics that physicists use to identify events. As an extra challenge you could ask students to sort the events by particle type, W, Z, and Higgs. Before class download and print out the event pictures on a color printer. Some teachers have laminated a "class set."

Here are event pictures in a PDF file. You will need Acrobat Reader which most browsers already have. We also provide a spreadsheet that lists the events number and type, W, Z or Higgs. Note: We use a simplified numbering system for your convenience.

You may also want to print out the first pages of the Excel spreadsheets to make it easier to help the students. We have provided links to the data that the students see and to the calculated results and graphs for you.

Finding B Evidence & B Lifetime

  • B data
  • B calculations and graphs
    Many subatomic particles exist for very short periods of time. How short? Try 10-13 seconds! In this project students will study the distance that a very energetic particle travels before it decays. Students can use this "decay length" to identify a B event and may calculate the lifetime as an extra activity. They apply rules of special relativity as the particles are observed in the lab frame.
    Concepts:Exponential decay, lifetime, time dialation.
    Skills: graphing, making histograms, graphical analysis and interpretation, using statistical decay processes, applying time dilation.

Finding W Evidence & W Mass

  • W data
  • W calculations and graphs
    The most interesting particles cannot be directly observed. They may decay too quickly or be created at rest. One can study products of a decay to learn more about the parent particle. The W boson may decay into an electron and a neutrino. Students use the momentum of the electron to identify a W event and may calculate the W mass as an extra activity.
    Concepts:Conservation of energy, momentum, mass-energy equivalence, indirect observation.
    Skills: graphing, making histograms, graphical analysis and interpretation.

W Mass Correction Factor - Z Mass

  • Z data
  • Z calculations and graphs
    In the previous investigation, students calculate the W transverse mass. This is not the actual W mass. We cannot calculate this directly because we cannot measure the 3-D mass of the neutrino into which the W decays. We need a correction factor which we determine from Z mass calucations. If you have time, your students can calculate the Z mass or you can give them the correction factor. We show two graphs, one with a correction factor of 1.22 and the other with a correction factor of 1.065.

    The most interesting particles cannot be directly observed. They may decay too quickly or be created at rest. The Z boson is the force carrier of the weak nuclear force and decays quickly into other particles that zoom through the detector leaving tracks and energy signals. Students calculate the Z mass in order to find a correction factor.
    Concepts:Conservation of energy, momentum, mass-energy equivalence, indirect observation.
    Skills: graphing, making histograms, graphical analysis and interpretation.

Where's Higgs?

  • Higgs observed data - Background
  • Higgs mass calculations and graphs - Background histogram
    When physicists look for new particles, they have to distinguish from similar events called background. Predictions indicate that Higgs decays into two B mesons and is accompanied by a W. Now that students can identify Bs and Ws, they use their judgement to select candidate Higgs events and interpret a graph of simulated events to find the Higgs mass built into the simulation.
    Concepts:Conservation of energy, momentum, mass-energy equivalence, indirect observation.
    Skills: graphing, making histograms, graphical analysis and interpretation.