Question

Backscattering of beta particles by foil experiment

Answer 1

When a β-particle (energetic electron from nuclear decay) enters a material its path can be deflected when it interacts with the nuclei of the material. The β-particles are oppositely charged to the positively charged nucleus and thus an attractive force exists between the two. The deflections that result are dependent on the initial energy of the β-particles but the effect is of a general scattering of the particles. This usually has the effect of changing the forward direction of a β-particle by a few degrees, but occasionally if the β-particle is suitably orientated in relation to the nucleus, the β will be deflected through a value of around 180◦ resulting in it exiting the material from the same side as it entered. It is this phenomenon that is known as backscattering