In this experiment we will study how \(\beta\) particles are attenuated when travelling through aluminium. We will measure the count rate using increasing thickness of aluminium between the source and the Geiger counter, and plot the count rate against thickness parameter.

Perform a measurement of the count rate using no aluminium discs. As you have seen in §\ref{distance} it is important to keep a constant distance between the source and the Geiger counter when measuring the count rate.

The easiest way to do this is to always place the source right against the Geiger counter, making sure they are as well aligned as possible.