The WIRED Event Quiz
Introduction
Now that you have looked through all of the events shown, it is time to test what you have learnt.
You will be shown a number of new events using WIRED, and it is up to you to use your new knowledge
to identify what is happening, in a similar way to a particle physicist working at DELPHI.
All of these events were observed with a collision energy of 91GeV, so a Z0 particle
was produced. Remember, there are a number of tricks you can use to identify each event.
Identifying Events
Most particle tracks will start with a coloured line in the central part of the detector. If no line
is seen, the particle is uncharged: probably either a photon or a neutrino. A photon will deposit
energy (shown as a coloured bar) in the electromagnetic calorimeter (shown as a white wire-frame).
The neutrino leaves no trace at all, and can only be identified by inference using the principle of
conservation of momentum.
If the particle does leave a coloured line in the central part of the detector, it must be charged.
Charged particles can be identified as:
- Hadrons (particles composed of quarks)
- Deposit a small amount of energy in the electromagnetic
calorimeter and the rest in the hadron calorimeter.
- Electrons and positrons
- Deposit all their energy in the electromagnetic calorimeter.
- Muons
- Deposit a small amount of energy in both calorimeters but, more
importantly, penetrate through to the muon chambers (muon chamber hits are represented as small
squares).
Once you know a few of the particles involved, you can work out what else is produced. Charged
particles must always be produced in pairs due to conservation of charge, and so if an electron or
muon is detected, a positively charged particle, such as a positron or anti-muon must also have
been created. Since quarks and gluons cannot exist on their own, they produce jets of hadrons.
Remember, some particles decay into others, which can complicate matters.
Now that you know how a physicist would analyse each event, you can try one for yourself. Look at
the event carefully, and then click on the equation below it that you think describes it correctly.
Good luck!
Navigation links:
[Back to Introduction]
http://hepwww.rl.ac.uk/WIRED/native-1.0/quizintro.html
last modified on 10th July 1998 by Alastair Wilson for
Tim Adye, <T.J.Adye@rl.ac.uk>