I recently had to do an experiment to show how aluminium absorbs β-particles from a strontium source. I was wondering, does the distance between the source and the aluminium sheet affect the absorption if the Geiger tube is the same distance from the strontium?

why don't you do some experiments and find out.

I belive that the absorbtion wont be effected but your detection might be flawed due to scattering from the aluminium...

Thanks, I'll look into those ideas.