- 3496 - MUONS - how they fit in the particle family? A Muon is one of 12 fundamental particles so far identified that make up the Universe. Actually there are 24 particles if you count one-for-one of anti-matter. All the fundamental particles in matter can be divided into 2 groups: Fermions and Bosons.
--------------------- 3496 - MUONS - how they fit in the particle family?
- To understand the experiment of Muon Capture we need to first understand, “ What’s a Muon?”.
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- Bosons are particles that carry the forces like the photons that comprise light and carry all electromagnetic forces, and gluons that hold nuclei together. Fermions are what make up all matter. Fermions can be divided up into 2 groups:
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- Quarks and Leptons. quarks are what make up protons and neutrons. Leptons are electrons and neutrinos. --------------------- There are 6 Quarks and 6 Leptons:
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------ 6 Quarks: -------------------------------
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------------- Up
------------- Down
------------- Strange
----------- Charmed
------------ Top
------------- Bottom
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------ 6 Leptons: -------------------------------------
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------------- Electron
------------ Electron Neutrino
------------- Muon
----------- Muon Neutrino
------------ Tau
------------- Tau Neutrino
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- All protons are made up of 2 Up Quarks and 1 Down Quark having a positive electric charge of 1
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- All neutrons are made up of 1 Up Quark and 2 Down Quarks having a neutral electric charge of zero.
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- The Muon is simply a heavy electron. The Tau is simply a much heavier electron, or a heavy Muon. The Muon is 200 times heavier than the electron. The Tau is 3,500 times heavier than the electron.
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- When physicists say “heavier”, they mean more mass or more energy. Remember mass and energy are the same thing according to E = mc^2,
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------------------- Energy = 90,000,000,000,000,000 * mass.
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- Mass is expressed in “electron-volts”, the energy to move one electron across an electric potential of 1 volt. Mass = E/c^2. So, mass is express in electron volts but the “c^2”, the speed of light squared, in the denominator is assumed and not stated. You are just supposed to know that by now. Duh!
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------ Leptons:
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------------- Electron ------------------------ 511,000 electron volts
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------------- Muon------------------------ 105,700,000 electron volts
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------------ Tau------------------------ 1,777,100,000 electronvolts
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All 3 of the neutrinos are nearly massless.
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------------ Quarks:
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------------- Up ------------------------ 300,000 eV
------------- Down---------------------- 600,000
------------- Strange-------------- 1,300,000,000
----------- Charmed-------------- 100,000,000
------------ Top--------------- 175,000,000,000
------------- Bottom------------- 4,300,000,000
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- All protons with 2 Up Quarks and 1 Down Quark = 938,200 eV
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- All neutrons with 1 Up Quark and 2 Down Quarks = 939,600 eV
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- These 12 particles and the 4 forces are the fundamental building blocks that make up the entire Universe, as we know it. The 4 forces are gravity, electromagnetism, Strong Nuclear, and Weak Nuclear.
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- The Muon Capture experiment involves shooting a massive Muon into a proton and having the Muon captured by the proton and becoming “Muonic Hydrogen“. Hydrogen is a proton orbited by an electron. If the proton captures the massive Muon the little electron goes flying off.
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- Muonic Hydrogen does not last long. It quickly decays into a neutron and a Muon Neutrino. When the Proton captures the Muon it involves the electromagnetic force. When the Proton+ Muon transform into a neutron and a Muon Neutrino it involves the Strong and Weak Nuclear forces.
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- Measuring all the energy levels involved with these 3 forces becomes very challenging for this experiment.
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------------ Muon + Proton ------>>>>> Neutron + Muon Neutrino
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------------ 105,700,000 eV + 938,200 eV ------>>>>> 939,600 eV + massless + K.E.
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- Due to the Conservation of Energy we can see that the rest of the mass must have transformed into Kinetic Energy, the energy of motion. Particles are flying apart.
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- The Muons are created in a particle accelerator cyclotron. A beam of Muons is created much the same as a beam of electrons is created in a Cathode Ray Tube, an old-style television.
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- The Muon beam is focused on a chamber of hydrogen gas, Hydrogen gas is an atom consisting of a proton and an electron. The gas chamber is surrounded by 3 cylinders of electron detectors.
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- The experiment has shown that 99.9% of the Muons decay before they are captured. Only 0.1% of the Muons are captured by a proton, and an electron gets ejected.
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- When the Muon decays it creates an anti-electron, an Electron Neutrino, a Muon Neutrino, and Kinetic Energy.
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--------------- Muon ---------->>>>>> anti-electron + Electron Neutrino + Muon Neutrino + Kinetic Energy
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- Muons were used to prove Einstein’s Theory of Time Dilation, time slows down for anything approaching the speed of light. Muon’s have a half-life of 2.197 microseconds. 63% of the Muons will decay in 2.197*10^-6 seconds when at rest in the laboratory.
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- However, when Muons are accelerated in a particle accelerator their time slows down and they live much longer Half-lives. Einstein’s formula for Time Dilation is called “Gamma” .
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- “Gamma^2 = 1 / 1 - v^2/c^2” where “v” is the velocity and “c” is the speed of light. If the Muons are accelerated to reach a speed where Gamma is 10^6, then 63% of the Muons decay in 2.197 seconds, instead of 2.197 microseconds. The time slows down for the speeding Muons exactly according to the Gamma formula. This just goes to prove that if you are fast enough you live longer. Einstein was right again, Duh!
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- On October 4, 2009 I attended a lecture at SSU by Tom Banks from Lawrence Berkeley Labs. His topic was experimental physics in Muon Capture. Tom received an award for having the best physics dissertation in 2008.
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March 12, 2022 MUONS - how they fit in the particle family? 3496
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