When a uranium nucleus was bombarded by neutrons, it was found that the products of the reaction were having a number of different half lives. It was assumed that in these reactions, we are producing trans uranium elements. If we attribute these different half lives to the successive disintegration of the same atom, one can explain the possibility of a single nucleus emitting several β –particles one after another. Obviously each β emission increases the atomic number of resultant nucleus by one and a series of new transuranium elements can be stipulated. These result aroused tremendous interest in the physical world.
O. Hahn and F. Strassmann then tried to identify the products of the reaction when uranium was bombarded will neutrons chemically and found to surprise of every one that these products were a number of different elements nearly all of which are in the centre of periodic table. They thus concluded that the uranium nucleus after the capture of a neutron seemed to be spilting apart into two nearly equal fragments as illustrated in the figure. These results were supported by Miss Lise Meitner and S. Frisch. They suggested that the neutron initiated a decomposition of the uranium nucleus into two nuclei of roughly equal size. The phenomenon was termed as nuclear fission.
