Bismuth nuclei energies

These fissioning nuclei (such as 8tP°i2-211> formed by reaction of Bi209 and a deuteron) have a nearly spherical normal-state structure, resembling that of the doubly magic nucleus seP m208, with an outer core of 16 spherons and an inner core of 4 spherons, shown in Fig. 6. The nucleus is excited, with vibrational energy about 25 Mev (for bismuth bombard-... 

Once a star s core temperature has reached about three billion degrees, fusion processes generate iron. And here they stop, because iron is the most stable nucleus of all. There is no energy to be gained by fusing iron nuclei. Yet heavier elements clearly do exist. They are created in the outer regions of the star, where neutrons emitted by fusion reactions are captured by nuclei to build all the elements up to bismuth (atomic number 73). 

Astatine could not have been made using the small cyclotron of 1936. But as soon as a bigger one became available it was possible to bombard bismuth with alpha particles of sufficient energy to penetrate the nucleus. 

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