A photographic emulsion impregnated with a radio- active thorium salt reveals the tracks of alpha particles when developed. As Ernest Rutherford & Frederick Soddy found in 1900-1902,the decay of thorium initiates a chain of decays. First one radioactive element is formed,then that decays to another,& so on. This is why the emulsion picture shows the tracks of two or more alpha particles emerging from the same spot: they are the result of successive stages in the decay of a single nucleus. (The length of the alpha tracks in this negative picture is about 0.03 mm) | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Powell, Fowler & Perkins |
Taille de l’image : | 4132 px × 3157 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |