The attenuation of radiation as a function of distance can be measured using a radiation counter with a Geiger-Müller tube that is sensitive to α, β, and γ radiation. We used exempt plastic-disc sources containing Polonium 210 (210Po), Strontium 90 (90Sr), and Cobalt 60 (60Co) to experiment with the penetrating power of α, β, and γ radiation in air.
With the setup shown in this picture, we experimented with how radiation counts decay for each of the sources as the distance between the source and the GM tube window is increased between 1cm and 1m. We selected the sampling distances for each source remembering that α is very short range, β has a range of about 10 cm in air, and γ gets weaker with distance but doesn’t come to a stop at any particular distance. We also assumed that the sources emit equally in all directions, and were able to calculate the effect of air’s density (~1.3 mg/cm3) in attenuating each of the radiation types.