Each fission reaction splits the nucleus of an atom of uranium-235 or plutonium-239 into two smaller atoms and releases a great deal of energy.

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The principle behind these experiments is that particles hitting the xenon cause the nucleus of the atom to give off a little bit of light.

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Laser interferometers are looking for disturbances in their experimental set-ups that are equivalent to mere fractions of the diameter of a proton, one of the particles that make up the nucleus of an atom.

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One effect of the beam is to polarise the cloud of electrons surrounding each rubidium nucleus, meaning that part of the atom becomes a negatively charged pole, and part a positively charged pole.

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