Muon (µ ± )

1. 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 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.