Radiation

• Types of nuclear radiation

  • Alpha
  • Beta
  • Gamma
• Which type of radiation is the most penetrating in air

  Gamma
• Penetration in air of alpha, beta, and gamma radiation

  A few cm, 1m, and unlimited, respectively
• Which material can stop alpha, beta, and gamma radiation

  Sheet of paper, thin aluminium sheet, and thick lead, respectively
• Which type of nuclear radiation does not cause a change in the structure of the nucleus when it is emitted

  Gamma
• Radioactive activity

  The rate at which a source of unstable nuclei decays
• Unit used to measure the activity of a radioactive source

  Becquerel (Bq)
• Radioactive count

  Number of decays recorded each second (by a detector, e.g., Geiger-Muller tube)
• Background radiation comes from rocks, cosmic rays, fallout from nuclear weapons testing, nuclear accidents
• Nuclear fission

  The splitting of a large and unstable nucleus into two smaller nuclei
• How nuclear fission occurs

  An unstable nucleus absorbs a neutron, it splits into two smaller nuclei, and emits two or three neutrons plus gamma rays