Half-life

• Half-life - time taken for the number of nuclei to halve or for the activity to halve
• A short half-life means:

  • source presents less risk, as it does not remain strongly radioactive for long time
  • as initially it is very radioactive, but it quickly dies down
  • so less of a long-term risk
• A long half-life means:

  • source remains weakly radioactive for a long period of time
  • weak activity means won't cause much harm to anyone