Using radiation and ionisation

We’ll look at industrial applications first; medical applications are a bit more complicated.

Two properties of radioactive materials make them useful for the industry:

• The radiation ionises other materials.

• The emitted radiation can be detected, giving you a clear image of where the radioactive material is.

Alpha radiation

Ionisation is useful for smoke detectors. Radioactive americium releases alpha radiation, which ionises the air inside the detector. Ionised air conduct electricity so you have a closed circuit. Smoke from a fire absorbs alpha radiation, making the air non-conductive again, this change triggers the alarm. These types of smoke detectors however are illegal to own since 2020. They haven’t been sold since 2010 and last about 10 years so don’t worry. 

Beta radiation

Beta radiation is used to monitor the thickness of materials such as paper, plastic and aluminium. The thicker the material, the more radiation is absorbed and the less radiation reaches the detector. It then sends signals to the equipment that can adjust the thickness of the material.

Gamma radiation

Because gamma radiation in large doses is quite lethal to living cells, it is used not only to kill cancer cells (we’ll discuss that in the next chapter) but also to sterilize equipment.

Tracers

Radioactive substances that emit beta radiation or gamma radiation are used as tracers in industry and hospitals. A small but detectable amount of radioactive material is introduced to the pipe system (which might be underground) so the researcher can detect the flow of the gas/liquids. This way he can map any leakage, blockage or the normal route without digging up the entire pipe system. 

The materials can also be used at an exhaust where the water from the factory drains back into nature to see which parts of the river of lake are affected by the exhaust.

Assignments (don’t forget the table on the previous page)

58. Explain why Beta radiation is not suited for use in smoke detectors.

59. Explain why Alpha radiation can’t be used as a tracer.

60. Explain why Gamma radiation can’t be used to measure the thickness of paper.