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Asked by alexm to Dean, Jess, Luisa on 25 Jun 2010 in Categories: General.
Question: What are muons?
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Luisa Ostertag answered on 24 Jun 2010:
Found on wikipedia.org (because I did not know):
‘The muon (from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with a negative electric charge and a spin of 1⁄2. Together with the electron, the tauon, and the three neutrinos, it is classified as a lepton. It is an unstable subatomic particle with the second longest mean lifetime (2.2 µs), exceeded only by that of the free neutron (~15 min). Like all elementary particles, the muon has a corresponding antiparticle of opposite charge but equal mass and spin: the antimuon (also called a positive muon). Muons are denoted by μ− and antimuons by μ+. Muons were sometimes referred to as mu mesons in the past, even though they are not classified as mesons by modern particle physicists (see History).’
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Dean Whittaker answered on 24 Jun 2010:
muons are like electrons but have a bigger mass. Everything else about them is the same.
The standard model, which is the rubbish name for the theory of particles predicts lots of different particles that are all linked. You can get heavy protons, heavy neutrons etc. as well. You can also get positrons (the electron’s antiparticle)…. None of these heavy things are around in nature because they decay into the lightest thing that they can – in this case an electron. That’s because everything is trying to reduce it’s energy all the time and mass and energy are related. So the lighter you are, the less energy you have so as a particle you’re happier.
At isis (www.isis.rl.ac.uk) they use muons to look inside materials. By shooting them inside and letting them decay, then detecting the results of that, you can tell what the environment inside the thing they were shot into is like, how the electric fields and magnetic fields are behaving. I have no clue how you do this though, I just know they do!
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