Elementary Particles - Episode 2
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| Muons were mistaken for Sith |
Howdy, welcome to the second release in the series of the second release in the series of Elementary Particles. If you didn’t follow the previous release or just want to catch up click here.
Charged Leptons
Leptons are not affected by the strong force. They include the:
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| Elementary Fermions |
Leptons also include three types of neutrons that have no electric charge.
Muons were found among cosmic rays hitting Earth's surface. They were believed to be strongly interacting particles (Sith?) and were even thought to be the basis of the strong force. But a famous experiment performed by Marcello Conversi, Ettore Poncini, and Oreste Piccioni proved that Muons had no strong force interaction.
The muon and Tau are now understood to be essentially more massive versions of an electron.
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| Artistic imagination of muons among cosmic rays hitting Earth's surface |
Neutrinos
Neutrinos are electrically neutral and are of three different types:
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| 2nd group of leptons is of neutrinos |
One type is matched with each type of the charged leptons. Except for their masses the properties of the neutrinos have been well established. We know their approximate mass. They have a very small mass, no more than one billionth of a proton’s mass. But because they are so light (Ladies don’t be jealous) and so ghostly, we don’t have precise mass measurements.
Let me amuse you with a fact. Neutrinos interact so weakly with other particles that they can easily pass through thousands of miles of steel without ever “hitting” any particle in their way. Indeed it is a difficult and great challenge to detect a neutrino and measure their properties.
This process has demanding needs. It requires some of the largest and most massive particle detectors. The Super-Kamiokande neutrino detector in Japan has a mass of about 50,000 tons.
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| It's lots of fun if you are not being paid per detected neutrino! |
First generation Fermion rule
The twelve elementary fermions are grouped into three generations, each having two quarks and two leptons. In this case, generation does not mean descendants. Rather, this classification is based on the mass of a particle.
The third generation Fermions are more massive than their second generation counterparts that, in turn, are more massive than the first generation fermions. Because of their greater mass second and third generation Fermions have very brief life and are very rare in nature.
They are also much hard to produce in our laboratories and were discovered decades after their first generation counterpart (hence the use of generations).
Because of their rarity, the heavier fermions are of little importance to the evolution of the stars and the universe.
Everything we see is made up of first generation Fermions.
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| Quick Revise |
Are there more particles?
We have a good reason to believe, but no definite proof that there are no more elementary fermions beyond the twelve discussed in this series.
If the fourth generation existed then sure enough fourth generation neutrino would have also existed. Scientists believe that such an idea is improbable because the difference in the mass of the fourth- and third-generation neutrino would be huge (4th generation mass is billions of times more than 3rd generation mass).
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| The God Particle (Higgs Boson) |
Some have suggested the existence of additional types of particles, especially bosons. Most notable is the Higgs Boson which is believed to give different particles their different masses. However, till now, no other particles have been founded. If any of these particles is discovered they will surely be added to our list.
So much for matter.
But wait …….there is also Antimatter.
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