4.2.3

Types of Radioactive Emission

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The 3 Kinds of Ionising Emissions

Alpha, beta and gamma radiation all have different properties.

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Alpha radiation

  • Each alpha particle contains two protons and two neutrons.
  • Because of this, alpha particles have a relative mass of 4.
  • Because the particles are big and heavy, alpha radiation is strongly ionising.
  • It does a lot of damage but is stopped by a small amount of matter (like paper).
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Beta radiation

  • Beta radiation is made up of high-energy electrons.
  • Beta radiation is more ionising than gamma radiation but less ionising than alpha radiation.
  • It can pass through paper but is stopped by aluminium foil.
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Gamma radiation

  • Gamma radiation is weakly ionising.
  • It does less damage than beta or alpha radiation, but it is stopped only by centimetres of lead or meters of concrete.

Ionising vs Penetration

More strongly ionising radiation is less able to penetrate materials. It interacts with (damages) materials much more, so it comes to a stop sooner.

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Alpha radiation

  • Alpha radiation is like a bull running into a hedge.
  • It does lots of damage to the hedge but doesn’t get through very far.
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Beta radiation

  • Beta radiation is somewhere between the other two (alpha & gamma), like a cat running through the hedge.
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Gamma radiation

  • Gamma radiation is like a bird flying into the hedge.
  • It can dodge between the branches for a while, but will eventually get stuck.

Practical Applications of Radiation

We can use alpha, beta, and gamma radiation for many practical purposes:

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Smoke detectors - alpha radiation

  • A radioactive material fires alpha particles at a smoke detector.
  • If there is smoke between the radioactive material and the smoke detector, then fewer alpha particles will reach the detector.
  • This will set off the smoke alarm.
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Paper production - beta radiation

  • We can fire beta particles through paper in a factory to make sure that the paper being produced is the right thickness.
  • If the thickness of the paper changes, greater or fewer beta particles will reach the detector. Production can then be stopped.
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Exploring internal organs - gamma radiation

  • If we put a gamma-emitting isotope into a patient’s body, we can trace (follow) the radiation’s movement around the body.
  • Gamma radiation is the most penetrating type of radiation. This means it can pass through objects more easily than alpha or beta radiation. This means gamma can leave the body without creating too much damage (ionisation).
  • Gamma radiation also has a short half-life. This means that the radiation vanishes quickly.
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Sterilisation - gamma radiation

  • We can use gamma radiation to sterilise medical equipment in hospitals. Sterilisation kills bacteria and viruses.

Jump to other topics

1Energy

2Electricity

3Particle Model of Matter

4Atoms & Radiation

5Forces

6Waves

7Magnetism

8Astrophysics

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