Cloud Chambers
The cloud chamber was originally built by Wilson to study clouds themselves, however it was soon realised they were quite useful to the world of particle physics.
Once a diffusion chamber has been operational for about 10 minutes, something strange begins to happen. Within the mist appear lines of varying thickness and length, that appear to be shooting through the mist. There are also some lines which seem to branch off into two lines and some lines can take a non-linear path. These lines are caused by the ionisation of the atoms of gas or molecules of vapour, which in turn causes nearby molecules to be attracted and form a dense region around the original ion. The ionisation is caused by subatomic particles from cosmic rays and general background radiation. As the particles (most often muons) collide with the atoms/molecules, they knock off an electron. This process continues along the particles path and a line is formed. (To see a short video click here).
A straight line path is the track of a muon. A kinked path is the decay of a muon into an electron and two neutrinos, however, since the neutrinos carry no charge, they do not cause ionisation and their path is not visible. The branched paths are where an incoming cosmic ray has knocked an electron from an atom, the paths then seen are the knocked electron and the continuing cosmic ray.
It is also possible to place a magnetic field across the chamber which will cause the particles and hence the tracks to follow a circular trajectory, via the Lorentz force.
Once a diffusion chamber has been operational for about 10 minutes, something strange begins to happen. Within the mist appear lines of varying thickness and length, that appear to be shooting through the mist. There are also some lines which seem to branch off into two lines and some lines can take a non-linear path. These lines are caused by the ionisation of the atoms of gas or molecules of vapour, which in turn causes nearby molecules to be attracted and form a dense region around the original ion. The ionisation is caused by subatomic particles from cosmic rays and general background radiation. As the particles (most often muons) collide with the atoms/molecules, they knock off an electron. This process continues along the particles path and a line is formed. (To see a short video click here).
A straight line path is the track of a muon. A kinked path is the decay of a muon into an electron and two neutrinos, however, since the neutrinos carry no charge, they do not cause ionisation and their path is not visible. The branched paths are where an incoming cosmic ray has knocked an electron from an atom, the paths then seen are the knocked electron and the continuing cosmic ray.
It is also possible to place a magnetic field across the chamber which will cause the particles and hence the tracks to follow a circular trajectory, via the Lorentz force.
Use of the Chamber
