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Range of radiations

Question: I would like some help to do an experiment to determine the range of Alpha, Beta, and Gamma rays.


First of all remember that all radioactive substances can be dangerous. You must be really careful when using them and do so under supervision. I am sure you know this.
You don't say what material you want to find the range in so I will give you a variety of possibilities.

1. Air.
Set the source up in a holder facing along the bench with the Geiger tube in front of it.
You can test the range by moving the Geiger tube towards the source and record when you notice a sudden increase in reading. You could plot a graph of count rate against distance to show the effect of more air.
(a) alpha radiation this only has a short range (a few cm in air) and so the distances involved will probably be between 2 and 10 cm
(b) beta radiation this has a much longer radiation in air and so the distances involved will be between 50 cm and 10 cm
(c) gamma radiation this has a much larger range in air and so the distances involved will be from a 1m to 50 cm.
Of course will all the radiations the range is not exact, especially for beta and gamma and you may find it difficult to say exactly when the count rate increased.

2. Metals and other solids
Set up the apparatus as before but this time put the Geiger tube close (a cm or so) from the source.
Put different materials in between the source and the Geiger tube and record the reading. If you have different thicknesses of the same material put them in one after the other to get a graph of count rate against thickness.
The kind of materials I have tried have been: aluminium, lead, iron, paper, wood, covering film, tissue paper, bacon (to simulate flesh).

© Keith Gibbs 2011