The influence of distance on the intensity of radiation

Principle

Keeping the maximum distance away from a source of radioactivity is one of the most effective ways of of reducing the burden of ionizing radiation.
The quadratic dependence of the dose level on the distance, as given by geometrical considerations, assumes a point source and absorption-free propagation of the radiation. The Ra-226 source of radiation chosen for this experiment is a mixed emitter. It emits alpha particles as well as
beta and gamma rays. Of these, however, the counter tube registers almost exclusively only the beta rays, as the alpha particles cannot reach the counter tube because of their short range and the gamma rays are only registered by the counter tube with a response probability of
about 1%. The energy values of beta particles are continuously distributed over a region from 0 to a maximum value. As the range of beta particles of low energy is only a few centimetres, losses due to absorption occur with increasing distance of the counter tube from the source of radiation.,
which also causes a deviation from the square law of distance. It is therefore better here to do without the corresponding proof of this dependence, the students should come to the realization that the intensity of the radiation increases very strongly on nearing it.

Task

To determine how the intensity of the radiation emitted by a radiaoctive source changes on decreasing the distance from it.

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