Ei-9 Properties of Radiation Ei-9


To demonstrate the penetrating power of Alpha, Beta and Gamma-rays.


  • Geiger tube
  • Sr90 source
  • Retort stand
  • Paper
  • Aluminium foil
  • Lead blocks

Properties of Radiation


A commercial smoke alarm contains a weak Americium source which emits alpha particles. A single sheet of paper interposed between the source and detector reduces the count rate dramatically showing the weak penetrating power of alpha particles.

A Cs137 source emits both beta particles and gamma rays.

The same sheet of paper has little effect on these emissions but a thin sheet of aluminium will stop the beta particles. These particles may be shown to be electrons by deflecting them with a strong magnetic field. The gamma rays require a substantial thickness of lead to reduce the count rate.


Safety Notes

Properties of Radiation SOP-14