Radiation

• Why does the nucleus sometimes give out radiation?

  As it is unstable, to become more stable.

  This process is called radioactive decay
• What is activity?

  the rate at which a source of unstable nuclei decays

  so a sample with high activity has a fast rate of decay

  measured in Becquerel, Bq
• What is count rate?

  The number of decays recorded by a detector per second

  e.g. a Geiger-Muller Tube
• What are the forms of decay?

  • alpha (helium nucleus)
  • beta (electron)
  • gamma (radiation)
  • neutrons
• How ionising is alpha decay?

  highly
• How ionising is beta decay?

  medium
• How ionising is gamma decay?

  low
• What is the penetration like of alpha decay?

  weakly - 5cm of air
• What is the penetration like of beta decay?

  medium - 50cm of air, sheet of paper
• What is the penetration like of gamma decay?

  highly - very far in air, few cm of lead
• Exposure to low levels of radiation over long periods can lead to cancer. Why is this?

  • Radiation can cause mutations in our DNA
  • Which may cause our cells to divide uncontrollably
• Which factors determine how harmful the radiation is?

  • Where you’re exposed to the radiation
  • Type of radiation
  • Amount of radiation you receive