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Left: Aerial view of the accelerator ring......................................Right: End view of top quark decay
(Images courtesy of Fermilab)
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Left: Aerial view of the accelerator ring......................................Right:
End view of top quark decay
(Images courtesy of Fermilab)
In 1995 Fermilab announced that they had found the sixth and final quark. In this lesson, students can get a sense of how this was done by analysing a few events that just happened to be (mostly) two-dimensional. This lesson has students use conservation of momentum and the mass-energy relationship, E = mc^2, to find the mass of the top quark.
This lesson is based on a resource developed by Fermilab, which can be found at Mass of the Top Quark. It’s a great resource but I felt it could be altered slightly to make it easier for a teacher to learn and use. Fermilab has many resources for teachers but the quality varies greatly. You might want to read a review of Fermilab resources.
Interactive
Lecture (30 minutes)
The PowerPoint Massing the Top Quark
does a quick overview of the detector and the way data is displayed. The
class adds up the measured momenta and by conservation of mometum, finds the
mass of the neutrino that was produced but not detected. The total mass is added
and divided by two to get the mass of the Top Quark. Each student needs a multiple-choice
booklet, a worksheet and a copy of
Event 14022. Detailed
instructions and answers to the worksheet are provided in the teachers
notes. Question 4 is a good place to use whiteboards
and the last four questions can be assigned as homework.
Small Group Work (30 minutes)
Three similar events are provided for the students to analyze in small groups.Each
group needs one of the three events: Event
153, Event 26
or Event 553.
Interactive Computer Activity (30 minutes)(Optional)
If you are in the middle of a unit on momentum, this part of the lesson is probably
too far off topic. You might want to come back to it when you do electromagnetism.This
resource, Fermilabyrinth,
was developed by Fermilab. It is a series of 12 games that let the students
learn more about accelerators, detectors and the standard model. The quality
of the games is rather uneven – some are fabulous and some are a waste
of time. I recommend five of them:
1) Warp Speed is about accelerators and Push the Particle
is a great simulation that challenges the students to build the best linear
accelerator. An excellent application of electrostatics and
conservation of energy.
2) Ghost Bustin’ is about detectors and Particle Trapping and Detector Detail help the students under stand about the calorimeters used at Fermilab, CERN etc.
3) Law and Order is about the Standard Model of particles and Baryon Bonanza and Particle Families has the students classifying objects by similar characteristics.