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Manchester Physics Spark Chamber. Neutrally charged Atom. Positively charged Ion. Electron. Electric Fields. Muon (µ ± ).
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Manchester Physics Spark Chamber Neutrally charged Atom Positively charged Ion Electron Electric Fields Muon (µ±) As the muon passes through the spark chamber it collides with the neutrally charged atoms and ionises them by knocking off electrons, leaving free electrons and positively charged ions. The high voltage on the plates in the spark chamber create a strong electric field. The electric field accelerates the electrons and ions towards the plates. As the charged particles move towards the plate they collide with more neutrally charged atoms creating more charged particles. This continues in an avalanche process Cosmic rays are high energy particles from space that bombard the atmosphere of the earth. They range in size from sub atomic particles such as protons to the nuclei of iron atoms. When they reach the earth they collide with air molecules in the upper atmosphere. They then create huge showers of secondary particles. The only one of these particles that we can detect on the ground is called a muon (µ). A muon has the same properties as an electron, but is much heavier and has a lifetime of only 2.2 micro seconds (0.0000022 seconds). Because the lifetime of the muon is so short, if you were to measure how far it should travel, it would only go 660 metres before decaying in to an electron, however because of special relativity, from our perspective the muons live much longer than this and are able to travel several kilometres to reach the surface of the earth where we can detect them with our spark chamber. When the number of electrons in the avalanche reaches 100 million, an electric field forms due to the charged ions and electrons. This causes the electrons and ions to recombine, in doing so they release photons which ionises more particles, causing further avalanches. The different avalanches merge together until there is a continuous plasma between the high voltage plates. The plasma has a low electrical resistance which allows a spark to flow between the two plates.