Detecting Radiation

Identify instruments and processes that can be used to detect radiation

  • The three different types of radiation all have the ability to ionise gases:
    • Alpha radiation is strongly ionising.
    • Beta radiation is less ionising.
    • Gamma radiation is only weakly ionising.
  • Ionising ability and other properties can be used to detect radiation.
  • There are a variety of instruments that can be used for radiation detection:

Photographic film
Darkens when exposed to radiation
Cloud chamber
  • Contains a supersaturated vapour of water or alcohol
  • Radiation ionises some of the air, and the vapour condenses around the ions, tracing a path
Geiger-Müller Counter
  • Consists of a conductive tube filled with argon gas, with a high voltage being connected to the outer casing and an electrode
  • Radiation ionises argon atoms and the high voltage causes the resulting electrons to accelerate towards the electrode, ionising more argon atoms in their path
  • The resulting cascade of electrons constitutes and electrical pulse, which is detected by a counter
Scintillation counter
  • When certain substances are irradiated with alpha, beta or gamma rays (different substances for each type of ray), they emit a flash of light
  • This flash can be collected and amplified in a photomultiplier
  • The electric signal thus generated can operate an electric counter
Examples of radiation detection instruments

Easychem - Detecting Radiation